An overview of the content of the science pitch submissions can be found in this STScI Newsletter article.
By default all Roman scinece pitches are displayed. Be deselecting the options below, you can limit the results. Selecting multiple surveys will include all those surveys. Selecting a survey (or surveys) and any categories will limit the results to only those categories within the selected surveys. If no surveys are selected, then any categories selected will be from any of the available surveys. The table is also sortable by column. Just click on the column header. Click again to reverse the sort.
| Name | Affiliation | Co-authors | Title | Pitch | Survey | Category | Keywords | Year |
|---|---|---|---|---|---|---|---|---|
| Mark Elowitz | Independent Researcher | Searching for Interstellar Objects of Aritifical Origin Using Roman Galactic Plane Survey Data | The exploration of interstellar objects provides a fascinating glimpse into the processes and materials that exist outside our solar system. These objects, such as comets and asteroids, travel through interstellar space and occasionally pass through our solar system, offering unique opportunities for scientific study. One intriguing aspect of these objects is the possibility that they could include artificial probes sent by extraterrestrial civilizations. Observations are typically conducted using telescopes equipped with spectrometry and photometry tools to analyze the composition and trajectory of these objects. The extremely wide-field-of-view hosted by the future Roman Space Telescope would be ideal for carrying out a search for interstellar stellar objects (ISOs), whether they are determined to be natural (comet or asteroid) or of artificial origin. Data from the Roman Galactic Plane Survey archives could be used to search for ISOs, assuming there are multiple frames of the survey space taken with a cadence of a few weeks to allow the motion of these objects to be characterized. The motion of the candidate ISO can be analyzed to verify an interstellar origin, and potentially whether the object exhibits any anomalous accelerations upon entering the solar system. The discovery of an artificial interstellar probe would have profound implications for science and society, fundamentally altering our understanding of our place in the universe. It would not only confirm the existence of other intelligent life but potentially allow us to study technologies far beyond our current capabilities. | Galactic Plane Survey | solar system astronomy | ISO, Interstellar Objects, Solar System | 2025 | |
| Mohamed Amrar | Oukaimeden Observatory, High Energy Physics and Astrophysics Laboratory, FSSM, Cadi Ayyad University | Oukaimeden observatory , morocco , physics stellar | Working to search for variable stars within the galaxy in order to know their formation and their distance from us, as well as to know the elements present inside the stars and on their surfaces. | Galactic Plane Survey | stellar physics and stellar types | Stellar physis , spectroscopy stellar | 2025 | |
| Nicolas Lodieu | Instituto de Astrofisica de Canarias IAC Tenerife | High proper motion metal-poor brown dwarfs | Ultracool dwarfs are objects with spectral types later than M7. They encompass very low-mass stars brown dwarfs, and planetary-mass objects with mass across the hydrogen-burning and below. They are the most numerous objects in the Milky Way whose formation processes need to be contrasted with state-of-the-art models. The main goal of this science case is to discover and characterise high proper motion metal-poor very low-mass stars and brown dwarfs in the Galactic plane. Our group conducted an extensive photometric and spectroscopic follow-up of the nearest metal-poor brown dwarf known to date, WISE1810. We combine optical and near-infrared photometry and spectroscopy with a dedicated monitoring over several years to measure a relative trigonometric parallax of 112.2+/-8.2 mas, placing WISE1810 at 9 pc, about three times closer than previously thought at the time of discovery. Its luminosity makes it sub-luminous, implying a temperature below 1000K and a metallicity between -1.5 dex and -1.0 dex. WISE1810 will be observed during JWST Cycle 3 and represents a metal-poor substellar benchmark for upcoming surveys such as Euclid, LSST, and Roman. The revised distance of WISE1810 has a strong implication on the density of metal-poor brown dwarfs in our Galaxy. We expect to identify new high proper motion twins of WISE1810 in the Galactic plane survey of Roman, expanding significantly our knowledge of this emerging new population. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | subdwarfs, brown dwarfs, metal-poor population, survey | 2025 | |
| Archana Soam | Indian Institute of Astrophysics | Dust in higher latitude clouds (HLCs) | Mapping dust in high latitude clouds (HLCs) is important for various aspects of ISM physics. These clouds do not have any internal energy source, but most HLCs may be affected by the mean interstellar far-ultraviolet (FUV) radiation (van Dishoeck & Black 1988). Most of these clouds are not gravitationally bound and hence, they do not show any signature of star formation, but a few of them, e.g. MBM 12 (Luhman 2001 ) and MBM 20 (L1642; Malinen et al. 2014), show evidence of star formation. Thus, star formation is not considered to be a prominent process in most HLCs (Magnani, Hartmann & Speck 1996). Dust grain alignment is the key to map magnetic fields in the ISM. This has mostly been done in Galactic place regions till date but there is a lot remaining to understand the dust grain alignment and properties of magnetic fields at the higher latitudes. The dust mapping in HLCs is important to constrain the grain size and distributions which with the help of polarimeters can help in understanding the roles of magnetic fields in the formation and evolution of the HLCs and subsequent star formation activity in them. |
Galactic Plane Survey | stellar populations and the interstellar medium | 2025 | ||
| Emily Hunt | LSW, Center for Astronomy of Heidelberg University, Germany | Tracing the inner galaxy with star clusters in Roman | Star clusters are an incredible tool for tracing the structure and history of star formation in the Milky Way, providing insights about star formation that benefit all areas of astronomy. Gaia has prompted a revolution in the power of star clusters; but particularly towards the galactic center, Gaia is severely extinction-limited. Roman's community survey of the galactic plane could prompt a similar revolution in star cluster science in the inner galaxy. For instance, Roman's plane survey is likely to include many new clusters, as well as providing precise membership lists and parameters for existing inner galaxy clusters that far exceed those possible with existing infrared surveys such as 2MASS. The properties of this population could be used to trace the star formation and destruction rate of the inner galaxy, going back billions of years. For individual clusters, and particularly massive inner galaxy ones, study of the low and high ends of the IMF will be possible in greater detail than ever before. I would be very excited to try and contribute my experience from working with star clusters in Gaia towards the Roman plane survey. For instance, I feel basic proper motions and parallaxes - even if they're much less accurate than what we're used to with Gaia - would be very important to make clusters easier to detect and study, making it far easier to separate red foreground stars from reddened distant stars. For the science cases in the first paragraph, I would be excited to pursue or contribute to star cluster projects using Roman data. |
Galactic Plane Survey | stellar populations and the interstellar medium | Star clusters, Star formation, Initial mass function | 2025 | |
| Michael Werner | JPL/Caltech | Roberta Paladini and the SPHEREx ICES team | Linking SPHEREx to the Roman Galactic Plane Survey | NASA's SPHEREx MIDEX mission [PI Jamie Bock, Caltech: Crill et al., Proc. SPIE 11433, 2020; SPHEREx.caltech.edu] is scheduled to launch in early 2025 for a baseline two-year mission, during which it will obtain four all-sky spectroscopic images of the entire sky at wavelengths between 0.75 and 5µm. SPHEREx will have spectral resolving power between 35 and 130, depending on the wavelength band, a pixel size of ~6.2x6.2 arcsec at all wavelengths, and spectroscopic sensitivities which compare favorably with the 2MASS and WISE photometric surveys in their respective wavelength bands. After coaddition of the four surveys, the 5-sigma sensitivity of the final data will be better than 19.2 mag AB at 2µm. SPHEREx's unique all sky spectral data base will be used by the SPHEREx team to study galaxies and the extragalactic background light at mid-to-high galactic latitude. Importantly for present purposes, a team led by Gary Melnick [CfA] will use the SPHEREx data from the Galactic Plane in an ICES survey to study the growth and evolution of interstellar ices from the diffuse ISM into forming stars and protoplanetary disks. With a 2µm sensitivity of 23.7 in a short integration [AB mag, 5-sigma], a PSF of 0.175 arcsec at 2um, and a spectral resolving power of several hundred as opposed to SPHEREx's 41 at wavelengths shortward of 2µm, Roman will easily extend SPHEREx measurements in several important directions. Note that many of the most interesting SPHEREx targets will be deeply embedded and highly reddened, and thus most readily studied by Roman at its longest wavelength of 2µm. The SPHEREx ICES team has catalogued almost 10 million stars for which spectra will be generated by the SPHEREx pipelines [Ashby et al ApJ, 949, 103 (2023)]. Most of these stars will be considerably brighter than the 19.2 mag AB limit cited above. Naturally, these stars are concentrated towards the Galactic Plane; for example, there are almost 7 million proposed stars within 5 degrees of the Galactic Plane and 90 degrees of the Galactic Center. Thus, we do not propose a dedicated stand-alone survey aimed at SPHEREx targets; we expect that hundreds of thousands or more of the SPHEREx- cataloged objects would be included in any Galactic Plane survey. Even so, we have some preferences for the choice of survey parameters which we articulate in the following tables. Examples of the ways in which the Roman data could enhance the science value of the SPHEREx data include the following: Disambiguation of multiple sources which lie within a SPHEREx pixel and may lead to peculiar spectra; extension of SPHEREx measurements of highly reddened sources to wavelengths shortward of 2µm; higher resolution spectra of SPHEREx targets at wavelengths below 2µm where interesting spectral features due to crystalline water ice and H2 can be found; and identification of stars which have varied between the SPHEREx and Roman observations. | Galactic Plane Survey | stellar populations and the interstellar medium | Interstellar Ices, Interstellar Dust, Molecular Clouds, Protoplanetary Disks, Circumstellar Disks | 2025 |
| Dale Alan Bryant | Citizen Scientist/Science Writer | Galactic | Galactic plane evidence of past, dwarf galaxy, in-falling. Are there any, extant, stellar associations within the galactic plane, that represent stellar bodies that were once members of a prior, exterior, dwarf galaxy? | Galactic Plane Survey | stellar populations and the interstellar medium, the intergalactic medium and the circumgalactic medium | infall, stellar associations, dwarf galaxy, stellar stream, | 2025 | |
| Kumiko Morihana | National Astronomical Observatory of Japan (NAOJ) | Masahiro Tsujimoto, Daisuke Suzuki | Search for faint CVs along the Galactic Plane using short time variability | The Galactic Diffuse X-ray Emission (GDXE), which is apparently diffuse X-ray emission of a low surface brightness along the Galactic Plane, has been known since 1980s, but its nature has been a mystery for a long time. Its X- ray spectrum is described by two-temperature high thermal plasma (about 1 and 5-10 keV). and a remarkable feature in the X-ray spectrum is the strong Fe K emission lines (e.g., Koyama et al. 1996, Ebisawa et al. 2008, Yamauchi et al. 2009) comprised of the neutral or low ionization state line at 6.40 keV and highly-ionized ion lines at 6.68 and 6.97 keV. At the Galactic Plane, Chandra X-ray Observatory conducted a survey toward a blank field in the GP at (l,b) ≈ (28.5 °,0.0 °) and detected 274 X-ray sources down to 3×10−15 erg s−1 cm−2 (Ebisawa et al., 2001, 2005). These point sources had been considered to be active binary stars with hot coronae (Revnivtsev et al. 2011), magnetic cataclysmic variables (CVs; e.g., Hong 2012, Yuasa et al. 2012), and non-magnetic CVs in high accretion rate (e.g., Nobukawa et al., 2016, Xu et al., 2016). However, it is difficult to constrain the nature of these individual point sources from X-ray data alone due to a lack of X-ray photons. Follow-up observations in longer wavelength is thus important and NIR imaging and spectroscopy have been carried out the nature of some of these point sources was revealed, which are magnetic-CVs, non-magnetic CVs with high accretion rate, and quite white dwarf binaries (non-magnetic CVs with low accretion rate, hibernating CVs, and pre- CVs; Morihana et al., 2022). However, the spatial density of CVs estimated from H-alpha survey (e.g., 10−6 pc−3; Patterson et al., 1998) is smaller than the theoretically predicted value (e.g., 2×10−5 pc−3, Politano et al., 1996) and the estimated spatial density based on the equivalent width of 6.7 keV Fe line of the GDXE X-ray spectrum, which needs about 10-4 -10−5/pc3 (Yamauchi et al., 2009, Yamamoto et al., 2022), is also larger than the theoretically predicted one. These indicate that there are many unobscured CVs along the Galactic Plane. Then, we propose to search faint X-ray binaries, especially CVs, along the Galactic Plane using the data from the Roman Galactic Plane Survey. To efficiently search for CVs, we focus on that CVs are known to have hydrogen recombination emission lines such as Pa-beta (1.282 μm), Pa-alpha (1.875 μm), and Br-gamma (2.166 μm) with equivalent widths ranging from -10 to -170 angstroms in their NIR spectra (e.g., Dhillon et al., 1995, 1997, 2000). Additionally, CVs exhibit time variability with periods of 1-2 hours even during quiescence. The accretion in most CVs occurs via an accretion disk around white dwarfs. In the case of dwarf nova, this accretion disk is thermally unstable, resulting in a quasi-periodic, large-amplitude outburst with a magnitude increase of 2-6 magnitudes over periods as short as a day, known as dwarf nova outburst (e.g., Meyer & Meyer-Hofmeister 1981; Osaki 1989). The interval between outbursts varies from system to system and depends on the accretion rate and the disk size; for example, some types of dwarf novae outburst every few days, while other types of dwarf novae remain quiescent for several decades before outbursting again. Additionally, most CVs are variable, even if they do not exhibit dwarf nova outbursts. Therefore, we can identify CVs through repeated observations using filters that have a transmission on the recombination lines. We intend to use F184 or F129 filters to search for faint CVs. Since the equivalent width of the hydrogen recombination lines of Pa-alpha is 1.5-2 times greater than other hydrogen recombination lines in known CVs (e.g., Dhillon et al., 2000), F184 is more suitable than F129 for our purpose. Most of the Galactic Plane have been observed by the Chandra, which has been in operation for more than 20 years, and a huge amount of X-ray data has been accumulated. Light curves made from repeated observations lasting several tens of minutes using FW184 or FW129 for CVs candidates selected based on X-ray hardness can identify CVs. By using the power spectrum, we can select CVs; their power spectrum is expected to exhibit the power of the orbital period plus 1/f fluctuation, although a flare star with the same time variability is expected to have a flat power spectrum. Combined with data from the Galactic Bulge Time Domain Survey, we aim to reveal the origin of the GDXE and differences in the distribution of CVs in our Galaxy. |
Galactic Plane Survey | stellar populations and the interstellar medium | White dwarf stars, Variable stars | 2025 |
| Jianhui Lian | Yunnan University | Search for isolated stellar mass black holes | Stellar mass black holes (SM-BHs) are remnant of massive star evolution. Although the Milky Way is expected to host hundreds of millions of SM-BHs according to the Galactic stellar mass and stellar evolution model, only a few dozens have been identified. All of these SM-BHs, except for one case, are found in binary systems through x-ray emission for those with accreting disk or the motion of visible companion star. The only exception is an isolated black hole recently discovered via astrometric microlensing in the bulge region (Saha et al. 2022). However, the strict requirement of close alignment for microlensing between point source and lens impose strong limit on the number of SM-BHs that can be discovered, even in thebulge region. Here I propose a survey to systematically search for the SM-BHs for Roman telescope based on a new approach (Lian et al. in prep). The basic idea is to use microlensing technique but with smooth background source instead of individual stars. The foreground black hole will magnify the light from the region of the background with projected distance to black hole close and smaller than the Einstein ring. With high-resolution image, this signal will be a point source like a star, but with colors identical to the smooth background. This is the key to disentangle the signal from stars in the same field. Comparing to the microlensing event with star as the background source, the advantage of this approach is that all foreground SM-BHs will have a signal and can be detected as long as the image is deep enough. In addition, the signal is not transient but will maintain until the foreground SM-BH moves out of the background source. This gives us the opportunity to characterize the SM-BH in detail with follow-up observations. One ideal smooth background is the diffuse nebulae in the Galactic disk. The emission-line dominated spectrum of nebulae leads to distinct colors, especially in narrow-band filters, from the stars, significantly improving the efficiency and accuracy to search for the microlensing signal of SM-BHs. Carina nebula is one of the largest diffuse nebulae on the sky with apparent size of 2◦ × 2◦). It is located at 2.6 kpc from the Sun, not to close to leave few foreground SM-BHs (e.g., Orion nebula) or too far to be too small on the sky, thus very suitable to target for this survey. Based on our calculation (Lian et al. in prep), a SM-BH with mass of 7 M⊙ (typical for isolated SM-BHs; Corral-Santana et al. 2016, Saha et al. 2022) at a distance of 0.5 kpc in front of Carina nebula will have a net brightness of ~27 mag. With multi-band (at least one narrow and one wide bands) image with depth of 27 ABmag (point source at 5σ) and 4 square degree full coverage of Carina, we will be able to detect ~ 12 (7 M⊙) SM-BHs within 0.5 kpc. Multi-epoch observations over 5 five years will enable proper motion measurement of the signal, which will put more strict constraints on the distance and mass of the foreground lens. |
Galactic Plane Survey | stellar physics and stellar types | black hole, microlensing, emission nebula | 2025 | |
| Loren Anderson | West Virginia University | Ionized Hydrogen in the Galaxy | Diffuse ionized gas pervades the disk of the Milky Way and provides most of the Galactic ionized gas mass. This state of matter links feedback processes caused by high mass stars to ongoing star formation in molecular clouds. Diffuse ionized gas can be studied using a variety of methods, but all used to date have a fatal flaw. H-alpha surveys are very sensitive, but the line suffers from extinction and extant spectroscopic surveys are at low angular resolution (~1deg.). Far- infrared fine-structure lines are rather weak and work to date has only sampled relatively few sight lines. Radio recombination lines are weak but line stacking can achieve reasonable sensitivities, but at relatively poor (few arcminute) angular resolutions. Roman has an excellent opportunity to provide a wealth of information on the ionized ISM. Of primary importance is the 1.87um Paschen-alpha line. Ideally, the Galactic plane survey would be able to observe this line with low-resolution grism spectroscopy, but even narrow-band photometry would provide a dataset that cannot be obtained with other instruments. |
Galactic Plane Survey | stellar populations and the interstellar medium | 2025 | ||
| Wanggi Lim | Caltech/IPAC | YSO Outflow hunting with Roman WFI Grism | The [Fe II] lines at 1.257 µm and 1.644 µm are crucial NIR emissions that trace shocked ISM in jets and outflows from embedded YSOs, enhanced by Fe abundance from grain destruction and Fe atom ionization by FUV radiation. The Roman Wide-Field Instrument (WFI) Grism, G150, allows simultaneous observation of these lines, enabling a sensitive blind survey of multi-[Fe II] emissions, a significant improvement over previous studies such as ground based [Fe II] 1.644 µm Galactic Plane survey with narrow band imaging (e.g. Lee et al. 2015). With one minute exposures per pointing, Roman WFI G150 achieves comparable sensitivity with the ground based 1.644 µm image survey, and the relative line intensity ratio between the two [Fe II] lines (1.257 µm and 1.644 µm) can trace NIR extinction. This approach can identify YSO counterparts deeply embedded in the ambient medium, up to approximately 10 magnitudes of visual extinction (A_V) and derive NIR extinctions from a single exposure, while also allowing for kinematic tracing of outflow features. Covering 60 x 2 degree regions in the fourth quadrant of the Galactic Plane could be achieved in less than 150 hours, demonstrating the efficiency and potential of Roman WFI Grism observations. | Galactic Plane Survey | stellar populations and the interstellar medium | Young stellar objects, Interstellar medium, Star formation, Stellar jets, Molecular clouds | 2025 | |
| Filippo D'Ammando | INAF-IRA Bologna | Characterizing jetted AGN in the Galactic Plane in synergies with other MWL facilities | The identification and characterization of jetted AGN (in particular blazars, radio galaxies, narrow-line Seyfert 1 galaxies) in the Galactic plane is not easily accessible with the current facilities. A large sample of candidates and potential jetted AGN can be already obtained with X-ray and gamma-ray telescopes performing all-sky survey like eROSITA and Fermi-LAT. An increased number of sources will be observed during the LSST of the Vera Rubin Telescope. Roman's wide field photometric and spectroscopic capabilities will be crucial for the identification and characterization of jetted AGN in the Galactic Plane. Infrared time domain surveys offer a whole new opportunity to study sources that are obscured behind large columns of dust. Also the study of the host galaxy of jetted AGN will benefit from the near-infrared coverage of Roman. Moreover, the high resolution of Roman will allow us to distinguish between whether the events observed by LSST was a nuclear transient such as a TDE or AGN flare or an off-nuclear even such as a supernova. | Galactic Plane Survey | supermassive black holes and active galaxies | Supermassive black holes, Blazars, Galaxy jets, AGN host galaxies | 2025 | |
| Ken Freeman | Research School of Astronomy & Astrophysics, Australian National University | The metal-rich RR Lyrae stars of the Galactic disk | Background: While most RR Lyrae (RRL) stars near the sun are old (>10 Gyr), metal-poor ([Fe/H]< -1) and are part of the Galactic stellar halo, there is a sub-population of metal-rich RRL stars in the solar neighborhood with abundances in the range -0.9 < [Fe/H] < +0.2 that are clearly part of the Galactic disk. These stars have been known since Preston's (1959) paper. They rotate rapidly around the Galaxy and their velocity dispersion is low. It was not clear whether they belonged to the thin or thick disk. A recent unpublished study by Freeman and Morrison on a sample of a few hundred RRL stars with accurate abundances and kinematics shows that these apparently old, metal rich RRL stars have kinematics like relatively young stars of the Galactic thin disk. The origin and evolution of these metal-rich disk RRL stars is not understood. RRL stars of similar [Fe/H] are found in the inner Galaxy, and it is possible that their counterparts in the solar neighborhood have migrated from the inner Galaxy via radial migration. This migration process can generate a kinematically cold population in the outer disk (e.g. Vera-Ciro et al, 2014). The radial migration process itself is not well understood: it complicates the interpretation of the stellar populations of the Milky Way disk. This science pitch is aimed at expanding our understanding of the metal-rich disk RRL stars near the sun, and of how radial migration from the inner Galaxy contributes to the stellar populations of the outer disk. Prediction: a kinematically cold population in the outer Galactic disk is likely to have a strong concentration to the Galactic plane. So far, there is little data available on RRL distributions in the low Galactic latitude disk where the interstellar extinction is high. The proposal is to observe 4 regions of 6x2 deg, centered at b = 0 and at l = 0, 90, 180 and 270. For uniformity, the observations could follow the exposure time and dither strategy of the larger proposed survey of the inner Galactic plane (GRIPS: |l| < 60 deg) survey for uniformity. For each pointing, about 30 visits with irregular cadence spread over at least one year are proposed. The goal is to discover low latitude (|b| < 3 deg) metal-rich RRL stars in the Galactic disk and measure their proper motions. The filters to be used are F158 and F213. We note that the periods of these metal- rich RRL stars are mostly in the range 0.35 to 0.5 days. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | variable stars, astrometry, stellar kinematics | 2025 | |
| Etienne Bachelet | CALTECH/IPAC | Valerio Bozza, Jean-Philippe Beaulieu, Yiannis Tsapras, Markus Hundertmark, Rachel Street, Katarzyna Kruszynska, Sebastiano Calchi Novati | High-resolution imaging of all microlensing events detected in the Milky Way | The Roman's Galactic Bulge Time-Domain Survey is expected to produce a revolution in our understanding of exoplanets' demographics. This mission will explore the population of planets orbiting beyond a few AU from their host stars, discovered through the technique of gravitational microlensing. This survey will focus towards a ~2 square-degree region near the Galactic Center, where the microlensing event rate is highest. However, microlensing events have been discovered across the entire Galactic Bulge and Disk by large sky surveys such as OGLE, MOA, KMTNet, ZTF, ASASSN and Gaia. Moreover, it is expected that the number of discoveries will increase dramatically thanks to the capabilities of the Legacy Survey of Space and Time (LSST) at the Rubin observatory. Complementary observations using additional telescopes have often been crucial in characterizing the physical nature of many lensing events. One of the challenging tasks of the microlensing method is to reconstruct the mass and distance of the lensing object. A powerful technique that has been demonstrated to work is to obtain high resolution imaging several years prior/after the microlensing events peak. After this interval, the lens and source positions have separated on sky, allowing us to measure precisely their respective fluxes in several bands as well as their relative proper motions, to ultimately place constraints on the mass and distance of the lenses. This is now routinely done with Keck or HST. The combination of wide-field and small pixel-scale of the proposed Roman GP survey offers a unique opportunity to obtain such measurements for all the lenses that will be detected by LSST, as well as all historical events. Gaia has already delivered more than 300 events but microlensing surveys have observed more than 10000 microlensing events towards the Galactic Bulge during the last 25 years. High-resolution imaging will require two narrow, blue (F087) and red (F213), filters to extract strong constraints on the lens masses. Ideally, a third filter (F158) would be used to obtain optimal performance on the sampling of the Spectral Energy Distribution of the sources and lenses. To get a precise measurement of the lens and source separation, it is mandatory to collect several ditherings of the scene. However, it has been demonstrated that the reconstruction can be done even if the bodies are not separated, especially when three filters are used. The key components of this technique are the time baseline, between the high-resolution images and the event's peak, and the flux ratio between the lens and source. |
Galactic Plane Survey | exoplanets and exoplanet formation, stellar physics and stellar types | Exoplanets, Black holes, Astrometry, Infrared photometry | 2025 |
| Jaime Villaseñor | Max Planck Institute for Astronomy | Hans-Walter Rix, Maria Ramirez-Tannus, Eleonora Zari | Unveiling the Multiplicity of Young Massive Stars in the Galactic Plane | Overview Objective: Multi-epoch imaging of ~20 nearby very young (≲1Myr) dusty clusters with OB stars to uncover key aspects of massive star formation and evolution. Goals: * Determine at what separation massive stars began their lives as binaries (presumably wide). * Investigate how (quickly) they became close binaries. * Measure the stellar mass-function in such clusters down to the hydrogen burning limit. Method: A 2-3 year baseline, giving relative (transverse) velocities to ~1 km/s. Context Massive stars are fundamental to a multitude of processes within galaxies, from shaping their surroundings with strong ionizing winds to driving the chemical evolution of their host galaxies through feedback and supernova explosions, enriching their environments with newly processed chemical elements, which constitute the building blocks of planets and life. In the last decade, it has become clear that massive stars are rarely single, but mostly in multiple systems in orbits close enough to frequently interact with their companions. We have learned this mostly from spectroscopy in open clusters with ages between 2 and 10 million years. At these ages, most massive stars have cleared an important fraction of the gas and extincting dust from their birthplaces, permitting precise radial velocity measurements with optical spectrographs. However, little is known about the multiplicity characteristics of massive stars at birth. Observational studies of a small number of very young stars (~1 Myr) show companions at much larger separations (10 to 1000 AU) than those observed for older massive stars (>2 Myr). Modest amounts of multi-epoch imaging with Roman could be transformational for verifying and quantifying this seemingly dramatic age-dependent difference in the typical orbit separations of massive stars, and ultimately help us understand it. Understanding the multiplicity properties of these stars at the earliest stages is crucial for several reasons: (1) Star Formation Theories: It will test and refine models of massive star formation, such as core fragmentation and disk fragmentation. (2) Cluster Dynamics: It will enhance our understanding of the dynamical evolution of star clusters and the role of massive stars within them. (3) Stellar Evolution: Early multiplicity has profound implications for the subsequent evolution and fate of massive stars, including their potential as progenitors of supernovae, gamma-ray bursts, and gravitational wave sources. The high angular resolution and infrared capabilities of the Roman Space Telescope's Wide Field Instrument (WFI) will allow us to target key massive star-forming regions, where hundreds of massive stars have been detected using X-rays and infrared surveys. There are over 10 OB associations and subgroups scattered across the Galactic disk within 3 kpc, where stars as young as 1 Myr have been identified, yet many remain poorly studied. Multi-epoch imaging (e.g. 2-year baseline) would yield a (transverse) velocity precision of ~1km/s at a distance of 2 kpc (S/N~150 per epoch). This can quantify the (wide) multiplicity properties of massive stars in their earliest stages of formation. The 0.28 square degree field of view will enable us to efficiently cover most of the star-forming subgroups in a single pointing and to probe separations in the 10-1000 AU range. Dust extinction in very young massive-star regions precludes Gaia analyses, making Roman unique. These data may prove transformational for understanding the early dynamical interactions that shape the brief childhood of massive stars. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | Massive stars, Binary stars / Trinary stars, Star clusters, Initial mass function, High mass star formation | 2025 |
| Dante Minniti | Institute of Astrophysics, Universidad Andres Bello | C. Cáceres, L. Smith, P. W. Lucas, R. Benjamin, M. Gomez, A. Mejias | Free floating planets in nearby stellar associations | Nearby young associations are excellent laboratories to explore the low-mass regime before the sources cool down and fade beyond detection. A prime target is the Lower Centaurus Crux (LCC) association, that is located at a median distance of 120 parsecs with an age of 5-17 Million years. Importantly, the LCC would be partially mapped by the proposed Galactic Plane Survey. Our goal is to characterize the low-mass population in LCC in the near-IR, detecting free-floating planets in particular. As a pilot program, we have used Gaia EDR3 proper motions and parallaxes complemented with VVVX near-IR photometry of our VISTA Variables in the Via Lactea Extended near-IR survey, and DECam Plane Survey optical photometry to select a sample of low-mass objects in the LCC association. We computed the masses for these objects using evolutionary models, and established the free-floating planet population to all objects that have a J-band absolute magnitude MJ > 11.0 mag. We made optical and near-IR color-magnitude diagrams that show the brown dwarf and giant planet cooling sequences for the LCC plane region. On this basis, we predict that, using the proposed Galactic Plane Survey proper motions acquired with a separation of a couple of years, it will be possible to observe deeper down the giant planet cooling sequence for the LCC region in the near-IR CMDs. This would enable to compute a space density of massive FFPs for the LCC. In summary, direct imaging of nearby associations complemented by precise astrometry of the proposed Galactic Plane Survey with the Roman Space Telescope is an efficient technique for the search for FFPs. If our observations of the LCC are representative of the typical star-forming population found in the Galactic disk, we predict that there should be hundreds of FFPs that can be detected down to Neptune mass planets. |
Galactic Plane Survey | exoplanets and exoplanet formation, stellar physics and stellar types | Young stellar objects, Exoplanets, Free Floating Planets, Brown Dwarf Stars, Star Clusters | 2025 |
| Leigh C. Smith | Institute of Astronomy, University of Cambridge | L. C. Smith, D. Minniti, A. Luna, M. Rejkuba, P. W. Lucas, R. Benjamin, J. L. Sanders | Hypervelocity stars in the central region of the Milky Way | The fastest stars in the Galaxy are Hypervelocity stars (HVSs). They are typically thought to have been ejected by a three-body interaction of a binary system with SgrA*, the supermassive black hole (SMBH) at the center of the Milky Way. This HVS ejection scenario is known as the Hills mechanism, whereby one star is ejected as a HVS, while the other remains attached to the SMBH as an S-Star. Given the mass of Sgr A*, 4 Million M⊙, HVS velocities can reach up to about 4 000 km/s, much more than the local escape velocity in the Galactic centre (Ve ~ 830 km/s). Unfortunately, in current surveys, high stellar crowding and large and patchy extinction in the central regions of the Milky Way hamper the detection of HVSs close to their origin. There are around 20 confirmed HVSs and over 500 candidates, but these are all located in the Milky Way halo, with velocities ranging from 300 up to 1700 km s−1. However, in order to estimate the production rate of HVS from the SgrA* one ideally needs to sample the HVS near their creation site. While crowding is a severe limitation for such observations, the deep photometry and high resolution imaging capabilities of the Galactic Plane Survey with the Roman Space Telescope will provide accurate proper motions, alleviating the incompleteness due to severe crowding. Luna et al. (2024) searched for high-velocity stars in the inner region of the Galactic bulge using a selected sample of red clump stars with accurate proper motions. The search was carried out with a sample of preliminary data from version 2 of the Vista Variables in the Via Lactea (VVV) Infrared Astrometric Catalogue (VIRAC2) and Gaia DR3 data, providing accurate NIR and optical proper motions, respectively. Out of nearly 500 hypervelocity candidates, in total, They found 69 candidate HVSs pointing away from the Galactic centre with transverse velocities larger than the local escape velocity. The HVSs have flight times ranging between 24,000 and 4,800,000 years, implying an integrated ejection rate of 1.4 × 10^−5 per year. Nevertheless, the surveys are incomplete since their sample is limited to the red clump stars, and therefore the derived ejection rates are likely to be lower than the current estimates. Extrapolation from the red clump giants to fainter magnitudes, below the MS turn-off, would yield thousands of HVSs in the bulge. The Galactic Plane Survey with the Roman Space Telescope will provide the number counts necessary to map the history of accretion of the central SMBH. Its HVS discoveries, and their properties, will constrain the ejection rate and the shape of the initial mass function and the binary stellar population of the Galactic center region. Luna et al. (2024) argue that that their velocity distribution is compatible with current ejection models, where the HVSs should reside close to the Galactic center, and those ejected with the Hills mechanism will also have an isotropic spatial distribution. A different spatial distribution, or velocity distribution that does not point back to the Galactic center can be explained by competing ejection scenarios, such as a disruption of globular clusters by their SMBHs, inspiralling black holes of intermediate mass, dynamic interactions with binary massive black holes, or kicks by inner supernova. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | Stellar kinematics | 2025 |
| Maria Gabriela Navarro | INAF - Observatory of Rome | Dante Minniti | Long timescale microlensing events in the Galactic center region | Theoretical models predict a substantial population of stellar mass black holes freely moving in the vicinity of the Galactic Center without significantly interacting with other stars, making their detection challenging. Microlensing is a powerful technique for detecting dark objects, but the parameters obtained from the light curves are often degenerate. On a Galactic scale, the multiple images created by a microlensing event are separated by milliarcseconds, making it impossible to resolve them directly. However, the apparent shift in the position of the centroid of the source, due to the brighter major image, is detectable. Astrometric microlensing involves measuring this apparent shift in the centroid position during a microlensing event to break the degeneracy in parameter calculations, thereby allowing precise measurement of the mass of the lensing object, such as a white dwarf. The duration of microlensing events is proportional to the mass of the lensing object, requiring long-time baseline coverage (about one year) and observations in high stellar density environments to increase the chances of alignment. Therefore, the Galactic plane and center are prime observation targets. Extreme extinction in these crowded regions demands observations in infrared bandpasses. Predicting alignments for black holes is practically impossible. However, the VVV survey pioneered the search for long- timescale microlensing events with a 5-year baseline, extended by the VVVX for another 5 years, covering a total of 10 years with ongoing observations until 2020. This effort found dozens of long timescale candidates. Rather than predicting alignments, the proposal is to use the Galactic Plane Survey with the Roman Space Telescope to monitor the behavior of background stars around these black hole candidates in hand from 2010-2020 to detect lensing effects on nearby stars. Monitoring does not require a high cadence; observing once every few months is sufficient. When an apparent increase in brightness is detected, the source should be followed up to confirm whether it is an ongoing microlensing event. If confirmed, follow-up observations with high sensitivity and resolution in the near-IR are necessary. This project is cost- effective in terms of telescope time, requiring fewer than 10 observations to compute the mass of the lens, potentially leading to the detection of the first isolated stellar-mass black holes. |
Galactic Plane Survey | stellar physics and stellar types | Gravitational microlensing, Black holes, Galactic center | 2025 |
| Matthew De Furio | University of Texas at Austin | Daniella Bardalez Gagliuffi (Amherst College), William Best (UT Austin), Per Calissendorff (University of Michigan), Trent Dupuy (University of Edinburgh), Sam Factor (UT Austin), Clémence Fontanive (University of Montreal), Ronan Kerr (UT Austin), Adam Kraus (UT Austin) | Pushing the Limits of Star Formation: An in Depth Exploration of Star-forming Regions in the Galactic Plane | The detailed physics of star formation have proven difficult to theoretically model and require observations of star- forming regions to demystify this fundamental astrophysical process. The environmental properties of star-forming regions can vary widely, ranging from very low density associations with few stars to very high density, bound clusters with hundreds of thousands of stars to OB associations with low density but thousands of stars. Past studies have identified no difference between the distribution of masses, the initial mass function (IMF), across most stellar populations, although this remains unclear for substellar objects down to the limit of turbulent fragmentation, ~ Jupiter mass scales (Bastian et al. 2010). Importantly, environmental differences have been identified within the stellar multiple populations of Taurus (a low- density association) and the Orion Nebula Cluster (a high-density cluster), likely due to dynamical encounters during states of very high density (De Furio et al. 2022). With the Nancy Grace Roman Space Telescope (Roman), we can probe star formation properties across star-forming environments with a wide variety of sizes, densities, and ages in order to: a) characterize the very low mass end of the IMF down to planetary masses and identify any potential environmental impacts (e.g. metallicity, presence of OB stars), b) define the stellar and substellar membership unattainable from the ground or inefficient from other space-based telescopes, and c) characterize the populations of binary and multiple systems down to planetary mass primaries and angular resolutions of ~ 100 milli-arcseconds (mas). Current work with the Hubble Space Telescope and James Webb Space Telescope (JWST) is designed to explore the very low mass end of the IMF in dense embedded clusters. While no other telescope can match the sensitivity of JWST in the infrared, the field of view of NIRCam is nearly 100x smaller than that of the wide-field instrument on Roman. Ground- based telescopes and current space-based survey telescopes (e.g. Gaia) are not sensitive enough to detect the low-mass substellar population, particularly in regions with high extinction, and cannot attain high angular resolution over a large field of view. Roman is crucial to observing regions on large angular scales like OB associations, those with thousands of stars and potentially the most common location of star formation, in order to explore the fundamental features of the star formation process. Roman is the only observatory that can be used to characterize the substellar content across large scale star-forming regions in the near infrared while simultaneously exploring multiplicity down to separations of 100 mas. With the proposed boundaries of the Roman Galactic Plane survey (Sanderson et al. 2024), there are hundreds of observable known star-forming regions with a multitude of environmental conditions to be explored (Mercer et al. 2005). We request that when star-forming regions are within the field of view of the survey, the F129, F184, and F213 filters are used with two dither positions to fill any detector gaps to attain 5$ sensitivity to at least AB mag= 25.5 to identify water band and methane features of M, L, and T dwarfs. We minimally request that benchmark star-forming regions like Taurus, Sco-Cen, and the Orion Molecular Cloud Complex are entirely observed with these observing requirements if the sequence is not common practice for all regions. Lastly, we request that regions slightly above the Galactic Plane but outside the proposed boundaries are included for efficiency. Roman will serve as the gold-standard in star formation astrophysics, complementary to work done by JWST in deeply embedded clusters, and provide a large database for future archival research from the impact of star-forming environment on the formation of their stellar populations and the effect of massive OB stars on their environment to populations of free-floating planets and the formation and evolution of protoplanetary disks. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | Star formation, Star clusters, Initial mass function, Brown dwarf stars, Pre-main sequence stars, Binary stars/Trinary stars | 2025 |
| Laura Baravalle | IATE-CONICET | G. Coldwell, D. Minniti, M. V. Alonso, F. Duplancic, S. Alonso & A. Pichel | Galaxies and Quasars in the Zone of Avoidance | The VISTA Variables in the Via Lactea Extended survey (VVVX) is a near-IR survey of the southern disk and bulge of our Galaxy, made with the VISTA telescope at the ESO Paranal Observatory. Over the past 12 years we have been mapping a large region of the Galactic Plane that is severely affected by interstellar extinction using the JHKs filters. One of the goals of our survey was to unveil the background galaxies hidden by the Milky Way, in the Zone of Avoidance (ZoA). We have recently discovered and published catalogs of thousands of galaxies down to Ks ~17 mag, also with an unpublished catalog of nearly a quarter Million galaxies in the ZoA. We have also found and characterized distant high energy sources (quasars and AGNs). These are obviously tricky regions due to differential extinction and crowding, so that along the way we had to develop machine learning, automatic classifiers and other artificial intelligence tools. These tools are specially tailored for the task, so that we would like continue their development in order to apply to the search and characterization of galaxies in the Galactic Plane Survey of the Roman Space Telescope. Based on our work and given the depth and resolution of the Galactic Plane Survey, we estimate to find tens of millions of background galaxies and hundreds of quasars and AGNs at low latitudes, allowing to identify groups, clusters and map the large scale structure of the Universe hidden beyond the ZoA. |
Galactic Plane Survey | galaxies, supermassive black holes and active galaxies & large scale structure of the universe | Galaxies: Infrared photometry; Supermassive Black Holes and Active Galaxies: AGN host galaxies, Blazars, Quasar; Large-scale Structure of the Universe: Galaxy clusters, Galaxy groups | 2025 |
| Athina Meli | North Carolina A&T State University | Investigating the interplay between infrared observations, galactic magnetic fields, and cosmic rays | The study of galactic magnetic fields and cosmic rays has long been a fascinating topic. By combining infrared data with observations from other wavelengths, such as gamma-rays and cosmic-ray measurements, we can gain unprecedented insights into the complex processes governing our galaxy and beyond. Roman will undeniably provide us a powerful tool to unravel the intricate interplay that governs such fascinating phenomena. One of the key findings from recent studies is the correlation between the polarized infrared emission from interstellar dust grains and the magnetic field structure in the Milky Way galaxy. | Galactic Plane Survey | the intergalactic medium and the circumgalactic medium, Supernovae, star forming regions, black holes | 2025 | ||
| Kumiko Morihana | NAOJ | Yusei Koyama, Takafumi Kamizuka, Yuhei Takagi, Daisuke Suzuki | The synergy between ULTIMATE-Subaru and Roman of the Galactic Plane Survey | ULTIMATE-Subaru (Ultra-wide Laser Tomographic Imager and MOS with AO for Transcendent Exploration) is a project aimed at developing a new wide-field adaptive optics system (GLAO; the Ground-Layer Adaptive Optics, Minowa et al., 2020) and a Wide-Field Imager (WFI, Motohara et al., 2020) for near-infrared (NIR) imaging on the Subaru Telescope. ULTIMATE-Subaru can achieve high image quality (FWHM~0.2 arcsec at K-band) with GLAO over a wide Field of View (14 arcmin ×14 arcmin). Our survey plan includes approximately 300 nights of observation using ULTIMATE/WFI, incorporating unique medium-band, and narrow-band filters in addition to broad-band filters. As part of this plan, we will conduct a wide-field Galactic Plane survey covering about 60 square degrees (l = 20-50 deg and |b| < 1 deg) with ULTIMATE/WFI. This survey will utilize a variety of narrow-/medium-band filters (such as Pa-beta, CN, Br- gamma, [Fe II], etc.) adding to broad-band filters to study obscured objects including evolved stars, cataclysmic variables (CVs), supernova remnants, etc. The observations are expected to reach a confusion limit of Ks ~ 22 magAB in the survey area. Furthermore, we intend to observe several tens of star-forming regions with various environments using J-, H-, and K- band filters, along with narrow-band filters to detect water absorption bands. The Roman mission is set to begin operations before ULTIMATE, which is scheduled to start in 2028, and both missions are expected to achieve comparable observational depths. Together, the Roman Galactic Plane Survey and the ULTIMATE-Subaru Galactic Plane Survey will enable the tracing of long-term variations of objects within the Galactic plane. Furthermore, the deep broad-band images obtained by the Roman Space Telescope can be further explored using the unique medium-/narrow-band filters of ULTIMATE-Subaru/WFI. For example, it is considered that a large number of CVs are hidden in the dust on the galactic plane. CVs are known to cause outbursts that brighten by several orders of magnitude due to instabilities in the accretion disk. These outbursts have periods ranging from a few days to several years, or even decades, depending on the mass accretion rate and the size of the disk. The period of outbursts can also fluctuate during quiescent periods. Therefore, CVs can be identified through long- term variability by combining data from the Roman and ULTIMATE Galactic Plane Surveys. Furthermore, CV candidates can be identified through short-term variations using broad-band images from the Roman Space Telescope and X-ray archive data. Confirmation of whether the selected candidates are CVs or not can be achieved using narrow-band filters on ULTIMATE-Subaru, which exhibit transmission peaks in the hydrogen recombination lines characteristic of CVs. Additionally, it is anticipated that some of the reddest OH/IR stars found in the Roman Galactic Plane Survey will include non-variable OH/IR stars. These non-variable stars, previously undetected even in UKIDSS data, are expected to be faint in the K band (less than 17 Vega mag). The Roman survey will provide the first detection of such objects in the near-infrared. Interestingly, while it has been traditionally thought that the NIR emission of non-variable OH/IR stars becomes brighter and bluer as the surrounding dust shell dissipates after the end of the Asymptotic Giant Branch (AGB) phase, recent studies have shown that these stars indeed brighten over time but do not become bluer with time (Kamizuka et al., 2020). This suggests the occurrence of unexpected phenomena around the stars, such as sudden temperature changes and dust formation due to additional mass loss after the AGB phase. Further investigation into this color change will offer new insights into stellar evolution post-AGB. Given the long timescale of the color change, spanning a few decades, continuous data from the Roman and ULTIMATE-Subaru Galactic Plane Surveys will be invaluable for this purpose. Because of the wide range of scientific opportunities available, we propose to include the survey area of the ULTIMATE Galactic Plane survey to encompass that of the Roman Galactic Plane survey. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | 2025 | |
| Q. Daniel Wang | University of Massachusetts | Toward a 3-D Panchromatic View of the Galactic Center | The Galactic Center (GC) is a complex ecosystem. Around Sgr A* - the central massive black hole - are concentrations of old and young stars, as well as dust and gas, strong magnetic fields, cosmic ray flux, and gravitational tidal force. The concentrations of old stars are referred to as the bulge and disk, although their overall sizes and morphologies are still difficult to determine, largely due to the uncertain differential light attenuation produced by foreground and embedded dusty gas clouds. These latter clouds form streams within the so-called Central Molecular Zone, which contains about 80% of the densest interstellar gas in the Galaxy. Although massive star formation occurs in some of the clouds, most of them remain unusually quiescent despite their large masses. Sgr A* is also currently quiescent, but has apparently been active in the recent past. To understand the structure and interplay of these different components in this complex ecosystem, we will need to perform a comprehensive study of the GC; the Roman Galactic Plane Survey (RGPS), complemented by existing multi-band IR data, in particular our HST/NICMOS survey, will allow us to decompose the various stellar and interstellar components. First, we will be able to determine the extinction law and its possible variation across the field by analyzing the spectral energy distributions of well-observed relatively bright individual stars. Second, we will be able to compare the dust extinction map with the existing dust emission data to characterize the 3-D global spatial distributions of gas and stars, following a hierarchical Bayesian approach that allows the data to be modeled in a statistically rigorous and optimal way and with the use of different priors (Tang, Wang Q.D., et al. 2021). This spatial characterization will be complemented by the analysis of molecular emission lines to measure both kinematics and magnetic fields, and to identify coherent large-scale streams and local features. The interpretation of these results will be aided by existing and/or new complementary multi-wavelength observations, providing detailed diagnostics of the physical and chemical states of the dusty gas. These diagnostics, combined with the multi-dimensional characterization of the stellar and interstellar structure, will allow to test hypothesized trajectory solutions of the streams and to model their interactions with the environment. Specifically, we will address questions such as: what is the recent star formation history; how is star formation triggered in some clouds while it is globally suppressed in the Central Molecular Zone; how reliable are different gas mass estimates; how well is dust emission traced by molecular lines; why is the gas typically much hotter than the dust; what drives the large turbulent motions of the gas; and what role does Sgr A* play in regulating the extreme GC environment. This progress will also provide insights into astrophysical phenomena and processes in similar extreme environments that are common in other galactic nuclei and in high-z star-forming regions. What I have in mind is an observing program with the Wide Field Instrument in the three filters F106, F158, and F213, similar to the one proposed in the white paper "Galactic Roman Infrared Plane Survey" (Roberta Paladini, et al.), except that we will use a mosaic design of mapping with 1/4 FoV overlap between two adjacent pointings, as used in our large- scale HST/NICMOS Paschen-alpha survey (Wang Q.D. et al. 2010; Dong H., Wang Q.D. et al. 2011). This design will provide nearly uniform coverage of the entire survey field, except for the outer boundaries. Also importantly, the overlapping coverages will allow us to calibrate the relative shifts in astrometry or instrumental background levels in all pointings with an elegant simple matrix solution. This design and/or calibration approach has also been used in our X-ray surveys (e.g., Wang 1991; Wang Q.D. et al. 2002). |
Galactic Plane Survey | stellar populations and the interstellar medium | Galactic center, 3-D structure of stellar and interstellar distributions, star formation history | 2025 | |
| Philip Lucas | University of Hertfordshire | Dante Minniti, Bob Benjamin and Leigh Smith | Clusters and YSOs in the Galactic Plane Survey | The Milky Way contains an estimated 20,000 star clusters, most of which are unidentified or unconfirmed due to the twin problems of high foreground extinction and the high level of contamination by field stars. These clusters contain ~10^6 to 10^7 YSOs and main sequence stars. The Roman Galactic Plane Survey (RGPS) in F213 proposes to cover longitudes -80 < l < 80 degrees at two epochs separated by a few years, in order to provide precise proper motions for ~10^10 stars across the Milky Way. With a precision of order tens of micro-arcseconds/yr, it will be possible to distinguish genuine cluster members with a common proper motion from projected members with high confidence. This will allow us identify essentially all clusters across the Milky Way, young and old, and build a catalogue of YSOs that is 10-100 times larger than present SED-based catalogues, e.g. SPICY, cleaned of contaminants such as dusty AGB stars, and inclusive of pre-main sequence YSOs with little or no infrared excess. In the current Gaia era, the vast majority of known clusters are within 2-3 kpc of the sun. In the Roman era, a new atlas of pre-main sequence clusters will allows us to map star formation across the Galaxy, tracing the role of spiral structure and density waves in triggering star formation. The RGPS will be deep enough to include all young brown dwarfs out to several kiloparsecs, providing a definitive sample to probe the variations seen in the low mass IMF amongst nearby regions such as between Orion and Taurus-Auriga. The cluster mass function will also be firmly established. With the first epoch, the survey will complement existing datasets such as VVV, where contamination is a major issue. This, coupled with the SPHEREx dataset, will enable reliable samples of YSOs with ten year VVV light curves to be established, probing variations in accretion rate in protoplanetary discs. The higher spatial resolution and greater depth of Roman will also make it possible to verify or reject the many new low mass VVV globular clusters candidates detected in the Galactic plane. |
Galactic Plane Survey | stellar populations and the interstellar medium | Star clusters, YSOs, IMF | 2025 |
| Wanggi Lim | Caltech/IPAC | Tracing Sequentially triggered star formation with Roman | An idea of 'Sequentially triggered star formation' was introduced by Elmegreen and Lada (1977) as an innovative point of view of star formation activities in the Milky Way and beyond. This theory proposes that star formation can propagate through molecular clouds via a chain reaction, where the formation of one generation of stars triggers the next. Such a process can explain the observed patterns of star clusters and stellar associations, providing a dynamic perspective on the evolution of galaxies. However, proving this sequential star formation with observations is extremely difficult due to the nature of star-forming regions and young stellar objects (YSOs). The forming stars are typically deeply embedded in dense molecular structures, and the active star-forming regions are generally far (>500 pc), making it challenging to trace individual stars. There is not a direct observational evidence on this scenario up to this point. With the reddest image filter of Roman Wide-Field Instrument (WFI), F213, we can trace the stars embedded in the dense medium with highly precise PSF FWHM of ~0.175 arcseconds, offering a promising tool to overcome these observational challenges. A multi-epoch F213 image survey of nearby star-forming regions will give us a great idea about the motion of embedded YSOs, which can be combined with the motion of expanding shells, showing the first observational evidence of sequentially triggered star formation. Assuming YSOs are at a distance of 500 pc and have a typical proper motion of ~0.05 arcseconds/year, a two or three-epoch observation with Roman WFI F213, taken more than three years apart, will provide insights into the statistical results of triggering star formation, especially about the stack and collapse scenario. This approach will help us understand how the motion of YSOs correlates with the expansion of their surrounding shells, supporting or rejecting the sequential triggering star formation scenario and advancing our knowledge of star formation dynamics in molecular clouds. Potential Targets: Orion Nebula (M42), Eta Carinae Nebula (NGC 3372), Perseus Molecular Cloud (including NGC 1333 and IC 348), Taurus Molecular Cloud (including Taurus-Auriga), Pleiades (M45), Vela Molecular Ridge (including Vela Molecular Clouds), Cepheus OB3, and Cygnus X complex (including Cygnus OB2). |
Galactic Plane Survey | stellar populations and the interstellar medium | Star Formation, Young stellar objects, Molecular clouds, H II regions, Star formation histories | 2025 | |
| Tansu Daylan | Washington University | William DeRocco | Searching the Galactic Plane for Free-Floating Planets using Roman Space Telescope | By leveraging its high-cadence, high-precision photometric time-domain survey, the Roman Space Telescope will be uniquely positioned to discover low-mass Free-Floating Planets (FFP) in addition to those bound to microlensing host stars. In this science pitch, we highlight this opportunity and suggest additional metrics to be considered in the design of the galactic plane survey that would improve its sensitivity to FFPs. First, we note that to find low-mass FFPs, one needs a large sky-projected density of foreground FFPs, small but bright enough background stars, and a high temporal sampling rate. The former can be enhanced by choosing fields that contain rich globular or open clusters in the galactic plane expected to harbor significant amounts of FFPs. Toward this purpose, we analyzed the 3,006 clusters in the Milky Way Stellar Clusters (MWSC) provided by Kharchenko et al. (2013) in a rudimentary and non-exhaustive exercise. We performed a star cluster selection based on the richness of cluster (>50 stars detected within the core radius), position in the galactic plane (|b|<5 degrees), an angular size that is small enough to fit within the field of view of a Roman Wide-Field Instrument pointing (r ~< 20 arcmin), and a distance not too close to the observe or distant, i.e., 500 pc < d < 5 kpc, to get reasonable lensing cross sections. We found five clusters, i.e., NGC 869, King 7, NGC 2099, NGC 2158, and Berkeley 53, which could serve as suitable WFI targets as part of a broader galactic plane survey, which would strengthen FFP searches. Additional survey constraints could be placed by choosing background fields with a high density of stars and low extinction. Furthermore, the low-mass FFP yield of such pointings would be improved by choosing one of the redder passbands available to optimize sensitivity to small background stars that would reduce finite source effects and extend sensitivity to lower masses. |
Galactic Plane Survey | exoplanets and exoplanet formation, stellar physics and stellar types | Gravitational Microlensing, Exoplanets | 2025 |
| Arash Bahramian | Curtin Institute of Radio Astronomy | A deep and comprehensive view of X-ray binaries in the Galactic plane | A large fraction of the Milky way's X-ray binaries reside within the Galactic plane (~85% of high-mass X-ray binaries and 40% of low-mass X-ray binaries). A Roman Galactic plane survey will enable detailed studies of these systems, both individually and the population as a whole in multiple dimensions. Observations of the time-domain characteristics of these systems provide the means to understand variability and binary properties in these systems, multi- filter imaging, particularly in the infrared, would provide unprecedented opportunities to constrain properties of accretion and the donor in the system. In addition, the capability to detect new outbursts of X-ray binaries (which in many cases first show a rise in optical, infrared bands prior to the X-rays) paves the path to discovery and characterization of new transients and X-ray binaries. All these aspects, make the Roman Galactic Plane Survey unique in enabling a synergetic, multi-wavelength, all- encompassing approach in understanding the population of black holes and neutron stars in binaries in our Galaxy, their formation and evolution, and detailed exploration of accretion physics in extreme environments. |
Galactic Plane Survey | stellar physics and stellar types | Black holes, Neutron stars, Stellar accretion disks, Transient sources | 2025 | |
| Sean Carey | Caltech/IPAC | Roberta Paladini (IPAC), Jennifer Sobeck (IPAC), Luisa Rebull (IPAC), Sergio Fajardo-Acosta (IPAC) | Synergies with existing infrared surveys of the Galactic Plane | The combination of the data obtained by the high-precision astrometry satellites Gaia and Hipparcos enabled us to find accelerating nearby stars in the whole sky (e.g., Brandt 2021). The most-likely candidates that are accelerating them are companion objects orbiting the stars. The Gaia-Hipparcos astrometry data are sensitive to the acceleration caused by a brown dwarf and a giant planet. Therefore, the data are available as the signs of such a substellar-mass companion orbiting a nearby star, which we are searching for using the high-contrast imaging instrument SCExAO and CHARIS on the Subaru Telescope. Indeed, we have already discovered several substellar-mass companions including a massive giant plane (e.g., Kuzuhara et al. 2022; Currie et al. 2023). The high-spatial-resolution data obtained by the Roman Galactic Plane Survey (RGPS) are also available to identify the sources accelerating the nearby stars. Even if the sensitivity is not deep enough to detect a candidate companion, the RGPS data are available to provide an upper-limit to rule out a companion with a mass of some levels. If a companion is detected in the multiple visits, we can reveal the orbit of the companion and measure its dynamical mass as in e.g., Kuzuhara et al. 2022. Whether or not the candidate is detected in the RGPS data, we can follow up the target that is observed in the RGPS to perform a deep high-contrast imaging using a 8m-class telescope from the ground. In addition, if the RGPS provides the high-precision astrometry of a bright star without saturating it, the data is available as a reference point to calculate the astrometry acceleration as demonstrated by Brandt et al. in the astro2020 white papers. In particular, it is the uniquest to obtain astrometry measurements for M-type stars, because they are too faint to be measured by Hipparcos. Accordingly, the data of RGPS has an excellent potential to accelerate multiple topics for accelerating stars. The success of this idea depends on the observational strategies of the RGPS such as cadence and depth. |
Galactic Plane Survey | stellar populations and the interstellar medium | Young stellar objects, Interstellar dust, Astrometry, Evolved stars | 2025 |
| Masayuki Kuzuhara | Astrobiology Center of NINS, Japan | Identifying Nearby Stars Accelerated by Substellar-Mass Companions | The combination of the data obtained by the high-precision astrometry satellites Gaia and Hipparcos enabled us to find accelerating nearby stars in the whole sky (e.g., Brandt 2021). The most-likely candidates that are accelerating them are companion objects orbiting the stars. The Gaia-Hipparcos astrometry data are sensitive to the acceleration caused by a brown dwarf and a giant planet. Therefore, the data are available as the signs of such a substellar-mass companion orbiting a nearby star, which we are searching for using the high-contrast imaging instrument SCExAO and CHARIS on the Subaru Telescope. Indeed, we have already discovered several substellar-mass companions including a massive giant plane (e.g., Kuzuhara et al. 2022; Currie et al. 2023). The high-spatial-resolution data obtained by the Roman Galactic Plane Survey (RGPS) are also available to identify the sources accelerating the nearby stars. Even if the sensitivity is not deep enough to detect a candidate companion, the RGPS data are available to provide an upper-limit to rule out a companion with a mass of some levels. If a companion is detected in the multiple visits, we can reveal the orbit of the companion and measure its dynamical mass as in e.g., Kuzuhara et al. 2022. Whether or not the candidate is detected in the RGPS data, we can follow up the target that is observed in the RGPS to perform a deep high-contrast imaging using a 8m-class telescope from the ground. In addition, if the RGPS provides the high-precision astrometry of a bright star without saturating it, the data is available as a reference point to calculate the astrometry acceleration as demonstrated by Brandt et al. in the astro2020 white papers. In particular, it is the uniquest to obtain astrometry measurements for M-type stars, because they are too faint to be measured by Hipparcos. Accordingly, the data of RGPS has an excellent potential to accelerate multiple topics for accelerating stars. The success of this idea depends on the observational strategies of the RGPS such as cadence and depth. |
Galactic Plane Survey | exoplanets and exoplanet formation, stellar physics and stellar types | Giant planet, brown dwarf, astrometry, star and planet formation, high-contrast imaging | 2025 | |
| Sean Carey | Caltech/IPAC | Roberta Paladini (IPAC), Jennifer Sobeck (IPAC), Michele Bannister (University of Canterbury), Luisa Rebull (IPAC), Sergio Fajardo-Acosta (IPAC) | Roman Galactic Plane synergies with NEO Surveyor and other Planetary Science missions | NEO Surveyor is a NASA Planetary Defense mission that will conduct a time domain survey of a significant fraction of the sky at 4.6 and 8.0 microns starting in 2027. Significant portions of the Galactic plane will be covered with cadences that can sample protostellar variability (hours to days) as well as potentially detect outbursts and other transient phenomena (at least in a statistical sense). One set of transients to be investigated is the dust production events through planetesimal collisions in moderately young stellar systems. The signature of such an event is a 4.6 micron excess that lasts weeks. The Roman Galactic Plane Survey will provide import source priors which can be used to identify the quiescent SED of sources and understand the multiplicity of NEO Surveyor sources. A planetary science benefit of Roman priors is understanding the background sources towards the Galactic bulge (which intersects the Ecliptic plane) which may help with the characterization of slow moving (distant) objects. In addition, the direction of the Galactic bulge is a likely region for interstellar objects (ISOs) like 1I/'Oumuamua to approach the solar system from due to the motions of the Solar system in the Galaxy and the ISO counterparts to nearby stellar associations. Roman priors will help facilitate the identification of ISOs from Rubin and other time-domain surveys in the optical. Synergies with NEO Surveyor and Rubin will be maximized through careful design of the survey coverage and depth. 3 filters are required to provide enough information on stellar SEDs. The Roman survey data will augment proper motion studies with Rubin which will help remove contaminants when looking for solar system (or solar system approaching) objects. |
Galactic Plane Survey | solar system astronomy, exoplanets and exoplanet formation, Interstellar objects | Small solar system bodies, Debris disks, Planet hosting stars, Protoplanetary disks (Extrasolar) | 2025 |
| R. Michael Rich | Department of Physics and Astronom, UCLA | Christian Johnson, Analisa Calamida, Francisco Nogueras-Lara, Jason Sanders, Rainer Schoedel, Mathias Schultheis, Mattia Sormani, Niewls Niewmunster, Nils Ryde, Brian Thorsbro | A survey of the Galactic Plane Emphasizing the Central 2 kpc | The Roman space telescope has the unique characteristics of wide field, near-IR imaging, and a stable point spread function spanning the FOV, potentially useful for the development of an photometric/astrometric catalog that extends to regions of high extinction completely unavailable to Gaia. We advocate for a Galactic plane survey that spans the central 1o (+/- 0.5o) of the entire Galactic plane, but enlarges toward the Galactic center to encompass +/- 1o from - 30o < l < +30o , and to +/- 2o over -10o < l < +10o. Principle science cases include the kinematics, structure, mass function, and ages of the nuclear stellar disk, nuclear star cluster, inner bulge, and young populations in the plane. We anticipate using the F184 (HK) and F213 (Ks ) as workhorse filters that will enable the best possibility of penetrating regions of high extinction that characterize much of the plane. Specific areas and fields of interest, such as the Galactic center and nuclear stellar disk, along with the long bar and regions of star formation, would be targeted with additional filters and moderate cadence time domain observations. It is anticipated that the disk survey fields will have a minimum of two separated epochs per field to enable proper motion measurement. In addition to the astrometric catalog, deep high resolution imaging will enable IR identification of interesting sources such as X-ray sources and millsecond pulsars, and other objects of interest in the plane. The survey would also encompass highly reddened globular, open, and young clusters will be obtained. We envisage that the community will be invited to develop the contours of the Galactic Plane/Center survey, including field choice, depth, strategy, cadence, and filter selection and that all data are immediately public. If undertaken soon, the Survey can also identify fields of interest for Webb followup. | Galactic Plane Survey | stellar populations and the interstellar medium, Galactic structure | Young stellar objects, stellar kinematics, Galactic structure, Galactic Center, Nuclear Stellar Disk, Population II stars, Interstellar medium | 2025 |
| Valentin D. Ivanov | ESO | Census of Milky Way star clusters | There have been multiple studies searching for Milky Way stars clusters, hidden in the inner regions of our galaxy by extinction. However, the question what fraction of the true cluster population is known has rarely been addressed. We propose to take advantage of the uniform nature of the Romain data - free from atmospheric effects like seeing variation - to build a simulation of predefined artificial clusters and to recover it. For the first time this will yield an estimate of the true cluster population of our galaxy. | Galactic Plane Survey | stellar populations and the interstellar medium | Star clusters, Galaxy structure, Star formation | 2025 | |
| Ravi Sankrit | Space Telescope Science Institute | Annalisa Calamida, Andy Fox, David French, Debopam Som | Identifying Tiny Low-extinction Windows | The Roman Galactic Plane Survey will observe billions of stars and, among other results, will provide a map of the obscuration by interstellar dust at exquisite and unprecedented angular resolution. Our science pitch is to use this opportunity to also look for compact low-extinction sight lines amidst regions of higher extinction. The basic method will be to identify isolated groups of (or even individual) blue stars that are not (with high likelihood) part of the foreground. The number, distribution, and angular sizes of low-extinction sight lines found in this study will help us directly map the 3D structure of dust in the galactic plane. Follow-up spectroscopy of stars in these windows will allow us, via analysis of interstellar absorption lines, to probe the interstellar medium to distances beyond the obscuring dust clouds. If sight lines where the extinction is ultra-low exist, the survey and the follow-up spectra will allow us to identify them, and they will allow us to probe distant regions of the Galaxy. Even if there are only a handful of them, these windows of low-extinction will provide high value targets for future observatories. One may imagine, for instance, cases of bright UV sources all the way across or even beyond the galaxy that can be observed with HWO. We emphasize that it is the high angular resolution of Roman data that will enable the discovery of these tiny low-extinction regions. The major requirement for this science to be enabled is that the survey includes observations using as many filters as possible, but especially F062 in the optical to get the longest lever arm to identify low extinction sight lines. A secondary requirement is that the observations in the various filters go to comparable depths, as the blue sources, because they are distant, will be faint. In terms of the survey region, it will be ideal to include galactic latitudes up to, say, |b| ~ 3deg where the chances of encountering low extinction sight lines will be higher. |
Galactic Plane Survey | stellar populations and the interstellar medium | Stellar distance, Interstellar dust | 2025 |
| Laurence Sabin | Universidad Nacional Autonoma de Mexico, Instituto de Astronomia (Campus Ensenada) | Evolved Stars Study Group (IA-ENS) | Stellar Feedback: The Influence of Evolved Stars in the Galactic Plane | Evolved intermediate-mass stars are key contributors to the enrichment and, to some extent, the dynamics of the Interstellar Medium (ISM). From asymptotic giant branch (AGB) stars to planetary nebulae, novae, and other binary systems such as cataclysmic variables and symbiotic stars, all inject substantial processed material into the ISM. Analyzing the chemistry, dynamics, and physics of this ejected material is essential, not only for understanding ISM feedback but also for gaining deeper insights into these stellar objects themselves. The Galactic Plane hosts a high concentration of these evolved stars, making it an ideal region for a detailed analysis of their properties. First, the Roman Space Telescope will complement ground-based surveys by probing deeper into the obscured Galactic Plane, where many of these stars reside. Currently, there is a discrepancy between the number of theoretically estimated and the observed populations (for the different objects mentioned above) due, in part, to extinction issues and the limitations of ground based surveys' resolution (which might not be able to resolve closely spaced stars in clusters). With its large-aperture and high-resolution capabilities, Roman will overcome these challenges, enabling better detection and differentiation of individual stars and their associated structures. Then, taking advantage of the telescope's depth and resolution, we will also be able to identify and examine shells or envelopes around these stars and systems. The extension, morphology, composition, and dynamics of these structures provide key markers of stellar evolution and histories. Finally, time-series data will enhance our ability to detect binary systems, which play a critical role in the shaping of certain nebular morphologies, as well as planetary companions around evolved stars—a field that has recently become more observationally accessible. In terms of supporting tools, our group developed a Machine Learning algorithm dedicated to the photometric identification of these evolved stars and which could be applied to the Roman dataset. Also, ground based follow-up of these extended structures visible in the northern hemisphere, can be performed at the San Pedro Martir Observatory in Mexico. The Roman Galactic Plane Survey will definitely be of great help to tackle various issues and complete our knowledge about evolved intermediate mass stars and their feedback to the ISM. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | Evolved stars,Planetary nebulae,Chemical abundances,Interacting binary stars,Transient sources | 2025 |
| Rachel Street | Las Cumbres Observatory | Roman Galactic Plane Survey Committee | Windows to the other side of the Milky Way | Most surveys of the Milky Way to date have been unavoidably constrained to explore the ~half of the galaxy that includes our Solar System, since the far side of the Milky Way is heavily obscured in most regions by thick dust lanes. As a result, our understanding of galactic structure and populations is incomplete. Modern infrared and submillimeter surveys (such as VVV/VVVx, Herschel etc) have started to penetrate these dust lanes to reveal this galactic structure, and recent work by the VVV/VVVx team has identified a set of regions with high IR stellar density and low extinction - keyholes through which the other side of the Milky Way can be explored. Several have been identified at tangents to the Milky Way's spiral arms and other key structures. Since no previous survey or mission offers Roman's combination of wide-field, deep limiting magnitude and spatial resolution, the Roman Galactic Plane Survey has a unique science opportunity. We propose that the Roman's Galactic Plane Survey include multi-band imaging of as many of these keyholes as possible. The primary goal of this sub-survey will be to achieve deep limiting magnitudes through long exposures and/or co-added images. These will be used to derive a source catalog of objects spanning as wide a range of distances as possible. At minimum, these data could be obtained in a single visit, but additional science would be enabled if the set of integrations were obtained over multiple visits, spread out over at least several days. This would enable the identification of variable stars, notably RR Lyraes which can be used as distance indicators. Data should be obtained in at least 3 filters, chosen to both penetrate the dust extinction and to sample the SED of stars sufficiently well to enable classification of spectral type and ideally metalicity. Likely filter choices would be F129, F184 and F213, though this remains to be optimized. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | Galactic structure, stellar populations, stellar variability | 2025 |
| Carme Gallart | Instituto de Astrofísica de Canarias (IAC) | M. Zoccali (PUC, Chile), A.B. Queiroz (IAC, Spain), A. Calamida, M. Gennaro (STScI) | Deriving star formation histories from color-magnitude diagrams reaching the oldest main sequence turnoff in the Milky Way disk and bulge. | Age information is crucial to unravel the formation and evolution of the Milky Way. We are using color-magnitude diagram (CMD)-fitting applied to Gaia CMDs reaching the oldest main sequence turnoffs (oMSTO) to derive 'dynamically evolved' star formation histories (SFH) and age-metallicity distributions for the halo and disk of the Milky Way, and plan to address the SFH of the bulge in the future with the same method (with Roman or JWST data). We have demonstrated the accuracy and precision of the derived age distributions through many tests with mock populations, and also indirectly, by the fact that we reproduce extremely well the spectroscopic metallicity distribution of the samples under study by only fitting the observed CMD, with no prior metallicity information. For the disk close to the plane, and for the bulge, however, reddening is a killer, and it is challenging to reach distances beyond 1-2 Kpc with this method using Gaia data. Instead, Roman data from the Galactic Plane Survey will be ideal to derive SFHs with this technique for distant thin disk and bulge stars, being this probably the best possible dataset in the foreseeable future. The following papers could be consulted for more details on our current application of the CMD-fitting technique to Gaia data (Gallart et al. 2024, A&A, 687, A168) and on a former application of this technique to bulge CMDs (Bernard et al. 2018, MNRAS, 477, 3507). To conduct this science with Roman data we need observations in at least two bands (F106~Y, F213~K) or (F129,F2913), (F158-F213 is not suitable for this project), with both bands reaching one magnitude below the oMSTO with S/N=20 at least. A distance of 5 Kpc is set for the disk, by the need to use Gaia parallaxes to derive individual distances for disk stars. In the case of the bulge, a typical distance of 8.2 kpc can be adopted and the separation of foreground disk and bulge stars can be done using relative proper motions. The larger the area coverage, of course, the better, but the one proposed in Paladini's white paper is a good minimum. However, for this project, it would be more interesting to cover 180 degrees from the bulge to the anticenter (say l=-10 to 180), such that age distributions can be obtained for a wide range of Galactocentric radius (Rgc=3-4 to 12-13 Kpc) and azimuths. We will estimate the requirements in apparent limiting magnitude for the bulge and the disk cases, considering that the absolute magnitude of the old main sequence turnoff is M_Y=3.5, M_J= 3.25 and M_K=2.5 and that we propose to reach 1 magnitude fainter than that, with S/N=20. We use extinction ratios derived from the VVV survey (Alonso-García et al. 2017, ApJ, 849, L13) as A_Y:A_J:A_K=5.38:3.30:1.0. 1-BULGE: considering the distance modulus (m-M)_0=14.6 and a typical E(J-K)=3 (this would exclude the Galactic Center region), we need to reach apparent magnitudes of Y=26.3 J=23.4 and K=19.4 at S/N=20. That would require exposures of 49176s, 980s and 85s, respectively, as computed using the Roman ETC. For this reason, we conclude that we cannot use the Y band to derive SFH in the bulge. On the other hand, we exclude the use of the H band, because the H-K color range of the CMD in these bands is too narrow, comparable to the error in both magnitudes. Lower S/N is unsuitable for this project. In case that it is impossible to cover the whole bulge region with exposure times in J of 980 sec, we would suggest selecting a few key fields as a proof of concept. Another aspect of this program, particularly true in the case of the bulge, is that availability of (relative) proper motions are needed to separate populations at different distances, in particular, separate bulge from disk stars. For this reason, we highly support acquisition of at least a second epoch in F213 to derive relative proper motions. 2- DISK At a distance of 5 Kpc: considering a distance modulus of (m-M)_0=13.5 and a maximum extinction of A_V=3.5. and A_V/E(J-K)=6, we need to reach apparent magnitudes of Y=19.5, J=18.7 and K=17.6 with S/N=20, requiring exposure times of approx 20 seconds in all bands. In this case, using Y-K would be best thanks to the larger color baseline. For this project, we would favour covering a range of l=-10 to 180. |
Galactic Plane Survey | stellar populations and the interstellar medium | 2025 | |
| Ilaria Pascucci | Lunar and Planetary Laboratory/The University of Arizona | Probing Accretion and Outflows: A Slitless Spectroscopic Survey of Off-Plane Star-Forming Regions | I propose to survey nearby off-plane star-forming regions like Taurus, Lupus, Chamaeleon, and Ophiucus in the grism slitless spectroscopic mode. The proposed observations will achieve the first population-level characterization of jets and winds in nearby star-forming regions at a few tens of au resolution. This characterization is crucial to understand what mechanisms drive accretion and the evolution of mass of planet-forming disks (e.g., Pascucci et al. 2023, Protostars and Planets VII review chapter). It also lays the foundation for properly characterizing jets and winds in more distant star-forming regions, where they may only be detectable far from their driving sources, and contributes to a broader understanding of outflow-driving astrophysical objects, such as neutron stars and black holes. Additionally, these observations will demonstrate the grism's capability to spatially recover extended emission. The grism on Roman covers strong accretion, jet, and wind diagnostics like the [FeII] at 1.644um, the HeI at 1.083um, the HI (4-3), and the H2 v=1-0 (7-5) line. Emission from these lines has been recently mapped at subarcsecond resolution toward 4 Taurus planet-forming disks with JWST/NIRSpec in the IFU mode (Pascucci et al. 2024, Bajaj et al. submitted). These maps highlighted the importance of resolving structures at a few tens of au to pinpoint the origin of winds and uncover the processes driving disk accretion. Although the Roman grism has a spectral resolution six times lower than JWST/NIRSpec, its comparable spatial resolution, combined with its wide field of view, enables efficient mapping of entire regions, which is not feasible with JWST. A key advantage of slitless spectroscopy over narrowband imaging is its ability to fully remove the continuum, even when it dominates the total flux. Slitless spectroscopy of forbidden lines tracing jets at a few tens of au resolution has been demonstrated with HST/STIS in combination with the G750L grating toward a handful of Taurus sources (Hartigan et al. 2004). Two orientations separated by 90 degree would be preferable. |
Galactic Plane Survey | exoplanets and exoplanet formation, stellar physics and stellar types | 2025 | ||
| Valentin D. Ivanov | ESO | et al | Spectral library | The creation of the library a few aspects: (1) assembling a high-quality set of spectra of stars with known physical parameters - these will serve as leaning sample for AI classification and as simple templates for simple comparative spectral analysis; this requires to re-observe a set of well-studied stars. (2) development of diagnostic tools for certain physical parameters, useful for creating samples of objects that match users criteria; some preparatory work can be done in advance, just knowing the parameters of the spectra. This project has high potential legacy values. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | 2025 | |
| Valentin D. Ivanov | ESO | et al. | Spectroscopic extinction map | The stellar spectra let us derive physical parameters of target stars and once these are known, from the difference between the apparent and the model predicted continuum shape/SED we can derive the extinction. The apparent SED will be derived from the spectra themselves and extended with both Roman photometry and with ancillary optical data - Gaia and from the ground. This spectroscopic extinction map will have worse spatial resolution than a purely photometry based extinction map, but it will be more accurate and it will serve as a benchmark to verify and if necessary to correct the photometric extinction map. |
Galactic Plane Survey | stellar populations and the interstellar medium, the intergalactic medium and the circumgalactic medium | 2025 | |
| Peter Craig | Michigan State University | Laura Chomiuk, Elias Aydi | Searching for Nova Counterparts with Roman | The Milky Way (MW) disk and bulge are home to many of our Galaxy's classical, symbiotic and recurrent novae. Identifying their counterparts between eruptions is often difficult, especially in regions with high extinctions in the Galactic plane. Roman's Galactic Plane Survey presents an opportunity to detect and classify many of these systems for recent novae in the MW disk. IR data in particular are useful for classifying the companions in nova systems, where the optical suffers from significant accretion disk flux. The IR should be a better tracer for the brightness of the companions, enabling classification efforts for the companion stars. Classification will also require distances, which can be estimated based on extinctions, fluxes and a Galactic mass model. A catalog of companion classifications would allow a measurement of the fraction of novae with red giant companions. Longer wavelength photometric coverage with Roman, such as K-band equivalent imaging, especially covering regions of the plane with large extinctions and stellar populations, should enable this analysis. Beyond counterpart detection, the Galactic plane survey has potential for finding novae obscured in high extinction regions of the disk. There is reason to believe that many of the novae in the MW are systematically missed (De et. al. 2021) due to large extinctions, and Roman's long wavelength coverage (such as K band equivalent imaging) is ideal for finding some of this population. It is possible that there are differences in the nova counterparts compared to the well studied local (or off-plane and low extinction) sample, which could be studied with Roman and its ability to observe novae through relatively high extinction regions of the MW disk. Roman IR coverage of the MW plane could potentially identify a significant population of nova eruptions and their counterparts, and reveal some of the missing novae thought to be hidden in the Galactic plane. |
Galactic Plane Survey | stellar physics and stellar types | 2025 | |
| Peter Craig | Michigan State University | Laura Chomiuk, Elias Aydi | Examining Dusty Nova Shells with Roman | Of the ~10 detected nova eruptions in the Milky Way each year, approximately 50-70% show evidence in the IR (especially K band) for the formation of dust (Chong et. al. 2025). Dust formation in novae is not particularly well understood, as the environment around the white dwarf is bathed in a harsh radiation field of far-UV and soft X-ray emission that ought to be effective at destroying dust grains, thereby inhibiting dust formation. Yet novae produce significant amounts of dust, possibly in radiatively cooling regions behind shocks in the ejecta. How long this dust survives remains an open question, along with where in the ejecta the dust is produced, which may be related to the geometry of internal shocks in nova ejecta. Some nova remnants, especially those from recent eruptions of the last ~ 1 - 100 years, may still have a dusty shell of surviving dust formed during the eruption. Observations with the H/K and K bands (F184 and F213) from Roman could potentially constrain the amount of dust surviving in the nova shells, and in some cases even constrain the distribution of dust relative to the gas. Since the H/K filter includes the Paschen Alpha line, it will provide a tracer of the ionized gas in the remnants that can be compared against IR emission from residual dust. Understanding where in the ejecta dust is forming is key to a better understanding of dust formation in novae. Here the high angular resolution of Roman at 0.1'' will be highly valuable, as many of these recent nova shells are predicted to be ~0.5 - 2 arcseconds in diameter. For eruptions in progress, even infrequent K band equivalent data can be useful for identifying dust forming novae. In general there is a lack of IR photometry available for nova eruptions today, which could be improved with occasional coverage from the Galactic Plane survey. |
Galactic Plane Survey | stellar populations and the interstellar medium | 2025 | |
| Michael Kuhn | University of Hertfordshire | Lynne Hillenbrand (Caltech) | The Cygnus X and Carina Galactic Plane Regions | Some areas of the Galactic plane are more special than others (e.g., the Galactic Center, the central molecular zone, and a few localized regions containing the most massive star-forming regions). These are local, spatially resolved analogs of the regions studied in the extragalactic context, so important to cover. Meanwhile, the Galactic Plane survey need not be contiguous, and some regions of the Galactic plane are less interesting than others. The Cygnus X region in Quadrant 1 (d=1.4 kpc) and Greater Carina Nebula (d=2.3 kpc) in Quadrant 4 represent the two most substantial OB star-forming regions within 3 kpc of the Sun. Although these regions are located near the Galactic midplane, most of the suggested Roman Galactic Plane footprints stop short of these regions. However, shifting segments of the survey footprint could cover both regions without increasing the survey area. Both complexes contain early-type O stars and young stellar populations significantly in excess of 10,000 members. The Cyg OB2 association is at the heart of Cygnux X, with many (famous) young embedded clusters to either side (e.g., DR 21). The Carina Complex has a spine formed from the massive clusters Tr 14/15/16 surrounded by irradiated cloud structures (e.g., the Western Wall and South Pillars). The expected magnitude of a young 0.09 M_Sun star in the Carina Nebula with A_V~5 mag of extinction is F158 = 18.3 mag, so a Roman survey would easily detect the complete stellar population of these regions, providing clearer delineation of the star clusters and a full view of the stellar IMF. Our suggested survey region would include at least 6 deg in the Galactic plane for Cyg X (i.e., 76 < l < 82 deg) and 1.5 degrees for Carina (i.e., 287 < l < 288.5 deg). For Galactic latitude, -2 < b < 4 deg for Cyg X and -1.25 < b < 0 for Carina. For a 3-band survey strategy, we recommend the F158, F184, and F213 to provide the best constraints on the infrared spectral energy distributions of young stars and sensitivity to Pa-alpha emission from the HII region. Science questions addressed by these observations include: How are massive young stellar clusters assembled? Does O-star feedback enhance (e.g., triggering) or inhibit (e.g., cloud disruption) star formation? And how do extreme environments affect young stellar populations (e.g., variations in the IMF or accretion properties)? |
Galactic Plane Survey | stellar populations and the interstellar medium | star formation, OB associations, massive star formation, molecular clouds, young stellar object | 2025 |
| Andrew Saydjari | Princeton | Extinction and Extinction Curve Estimates towards NIR DIB Targets | Near infra-red diffuse interstellar bands (DIBs) represent a unique opportunity to obtain a large catalog of measurements (>105) for a tracer with both precise (2-4 km/s) kinematics and distance information. Catalogs of these NIR DIBs from APOGEE probe a significant volume of the Milky Way disk (out to 15 kpc from the Sun). Building on techniques developed for 3D dust mapping, these catalogs are being used to jointly infer the spatial and kinematic (4D) structure of our Galaxy. Synergies with the Roman GPS are two-fold. (1) Upcoming NIR spectroscopic surveys are running up against a lack of targeting information, especially in the plane, where 2MASS is simply too shallow in H-band to support continued massively multiplexed fiber spectroscopic surveys. The imaging from Roman GPS would have a huge impact on our ability to target upcoming surveys (AS5 == "After Sloan 5" == SDSS-VI) to increase the sampling density and volume of these DIB catalogs. These expansions would improve our kinematic reconstructions of the Milky Way that test and challenge our current models of Milky Way structure. (2) These large DIB catalogs serve as chemical tracers of the ISM. Preliminary results have shown (anti)-correlations between the DIBs and variations in the Milky Way extinction curve that provide insight into the processes shaping compositional variations in our Galaxy. However, these studies have been limited to only the solar neighborhood (<2 kpc) by Gaia's observational horizon. This strongly motivates Roman GPS obtaining at least 4-5 bands of photometry, for robust extinction and extinction curve determination that will push our understanding of dust compositional variation out an order of magnitude in distance from the Sun. State-of-the-art DIB catalogs from APOGEE that might be useful for survey footprint overlap evaluation are available upon request. |
Galactic Plane Survey | stellar populations and the interstellar medium | Dust, Interstellar Medium, Molecular Clouds, Structure and Morphology | 2025 | |
| Lynne Hillenbrand | Caltech | Don't Completely Neglect the Grism Opportunity | The Roman GPS, initially proposed in the Astro2010 decadal survey, is finally taking shape! However, the very limited number of hours devoted to this third pillar of the original WFIRST mission concept, means that hard choices need to be made. The basic challenge to those planning the GPS, is to optimize the area covered and the number of filters that are used -- in order to enable the broadest science. No one science case will carry the mission, or even the day. That is the beauty of surveys, which are selected based on their potential, not on their guarantees. This "science pitch" is submitted to make the point that the unique opportunity of space-based (no atmosphere) 1-1.9um spectroscopy at R=460 should be given serious consideration. Many science cases could be developed, but again, the science potential is stronger than the likely science one can write down today. What is guaranteed, is that spectra would uniquely disentangle object temperature and extinction, more accurately and certainly more precisely than photometry along. In addition, the grism would provide immediate identification of rare objects such as emission line sources of various types, instead of needing to ferret them out from colors that mislead or simply do not make sense. Along with the science enabled by the grism, or enhanced by it, there is also practical utility. A grism survey could be used to "train" the imaging survey that will be done in 1, 2, 3, or 4 filters, by providing the ground truth. My proposal is a simple one: along the galactic plane, take one grism image approximately every 10 degrees, leaving out the central regions towards the inner galaxy where the crowding would be severe. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | 2025 | ||
| Jael Rojas | Independiente | A Multi-Wavelength Study of the Galactic Bulge with Roman HLWAS and Radio Observations | We propose to search for H-alpha spectral emissions in the Galactic Bulge region using the Roman High Latitude Wide Area Survey (HLWAS). We will utilize the F070W and F062 filters of Roman's Wide Field Instrument (WFI) to detect H-alpha emission. This data will be cross-correlated with radio observations of 21 cm, neutral hydrogen maps, produced by GBT/SKA. The synergy between optical/NIR and radio observations can probe the Epoch of Reionization, the distribution of hydrogen in the early universe, and cosmic structure formation. This observations will help answer questions about galaxy formation, dark matter, and process that illuminated the early universe. |
Galactic Plane Survey | exoplanets and exoplanet formation, stellar populations and the interstellar medium, the intergalactic medium and the circumgalactic medium, Radioastronomy | High Latitude Wide Area Survey, cosmic dawn, galaxy evolution, star formation, Galaxy clusters, dark matter | 2025 | |
| Savannah Gramze | University of Florida | Adam Ginsburg | Star formation and HII regions with the Roman Telescope: SHIIRT | The Roman Galactic Plane Survey will be the first Galactic plane survey with enough infrared sensitivity to probe populations of stars in the bar. The Galactic bar lanes are a little-understood part of the Galaxy. We know they are there due to radio observations tracing out the high velocity (±200 km/s) gas associated with them and extra-galactic observations of other galaxies with bars. The bar lanes usher gas in along the bar to the Galactic Center, making them important for understanding the workings of the inner Galaxy, where star formation is apparently rare, and the initial conditions of material before it is accreted onto the Central Molecular Zone (CMZ). With Roman, we will be able to find stars associated with the bar lanes and measure distances to them for the first time. The Nancy Grace Roman Space Telescope will be the first telescope to give us an idea of where star formation is occurring along the bar. The only high mass star formation currently known on the bar is in Sgr E, with recombination line emission detected with the Green Bank Observatory. The environment of the bar lanes is potentially different from other known star formation environments, and Roman will be the first telescope able to map out recombination line emission in the inner Galaxy to let us identify Galactic bar star formation regions and identify if they are different. We expect this star formation to differ from disk and CMZ star formation as the gas there experiences more shear and high velocity shocks due to being flung around the Galactic Center. Identifying these star formation regions requires the use of the F184M band, covering Paschen alpha emission that will be bright in any high mass star formation region, and is unavailable from the ground. A survey for HII regions in the inner Galaxy should cover at least |l| < 10, |b| < 1 to identify the population of HII regions that are too extincted for optical surveys and too faint for radio surveys to have identified. |
Galactic Plane Survey | stellar populations and the interstellar medium | 2025 | |
| Laurence Sabin | Instituto de Astronomia, UNAM | Stellar Feedback: The Influence of Evolved Stars in the Galactic Plane | Evolved intermediate-mass stars are key contributors to the enrichment and, to some extent, the dynamics of the Interstellar Medium (ISM). From asymptotic giant branch (AGB) stars to planetary nebulae, novae, and binary systems such as cataclysmic variables and symbiotic stars, all inject substantial processed material into the ISM. Analyzing the chemistry, dynamics, and physics of this ejected material is essential, not only for understanding ISM feedback but also for gaining deeper insights into these stellar objects themselves. The Galactic Plane hosts a high concentration of these evolved stars, making it an ideal region for a detailed analysis of their properties. Currently, there is a discrepancy between the theoretically estimated and observed populations of these objects due, in part, to extinction issues and the limitations of ground based surveys' resolution (which might not be able to resolve closely spaced stars in clusters). With its large-aperture and high-resolution capabilities, Roman will overcome these challenges, enabling better detection and we will also be able to identify and examine shells or envelopes around these stars and systems. The Roman Space Telescope will complement ground-based surveys such as the EGAPS (European Galactic Plane Surveys) by probing deeper into the obscured Galactic Plane,where many of these stars reside. Therefore, scanning the GP at -5° < b < +5° and 29° < l < 215° and including the bulge at -10° < b < +10°., the Roman GPS will be the red counterpart of EGAPS by mapping the area of interest in the J, H and K bands (where reside emission lines of interest, such as Pa-b, Brg,H2..etc, often found in the nebulae we are interested in). The bluest filter (F062) would also yield some interesting global information as it will help to differentiate stellar populations (old vs young), in addition of containing emission lines of interest. The deep IR data will allow us to trace evolved stars (such as the ones we identified in EGAPS) and in particular, the analysis of the extension, morphology, surface brightness, and dynamics/mass of these nebulae would provide key data on the stellar evolution and history. The full scanning of the observed areas can be done via Machine Learning techniques or other color code schemes to identify the objects of interest (as done for EGAPS). Finally, ground based follow-up observations of these extended structures can also be performed for specific targets. The Roman Galactic Plane Survey will definitely be of great help for this ample legacy-type project designed to tackle various issues and complete our knowledge about evolved intermediate mass stars and their feedback to the ISM. Also, a potential use of the Roman data in citizen projects or by amateur astronomers can give a huge visibility to the GPS, as plenty of evolved stars (in particular PNe) have been discovered by those groups via the scanning of survey data. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | Evolved Stars, Dust, Evolution,Planetary Nebulae, | 2025 | |
| Sara (Rosaria) Bonito & Laura Venuti | Italian National Institute for Astrophysics (INAF) - Osservatorio Astronomico di Palermo, Italy | Alessandro Salvatore Tramuto (Univ. Palermo - INAF - Osservatorio Astronomico di Palermo, Italy) | Young stellar objects: investigation of a diverse range of variability timescales | Young stellar objects (YSOs) exhibit variability over orders of magnitude in flux and in timescales (Fischer et al. 2023, PPVII). A very diverse range of physical processes are embedded in this variability, encompassing mass accretion from the disk to the star, dust extinction due to warped inner disks, stellar magnetic activity, and rotational modulation. The short-term variability domain (hours-days) offers a critical window into the dynamics of the accretion flow close to the star (Stauffer et al. 2015, AJ 149) and on inner disk instability processes (Stauffer et al. 2016, AJ 151). Roman Galactic Plane Survey will allow us to conduct high-cadence time domain observations of select star-forming region (SFR) fields (e.g. Carina Nebula and NGC 6611; Bonito, Venuti et al. 2023, ApJS 265). An observing strategy aimed at a dense coverage of these SFRs, with a cadence of one visit every 15-30 minutes and a stare duration of at least 24 hours, will provide us with the ideal baseline to discriminate between the different physical mechanisms that lead to YSO variability, in particular related to short-term accretion processes. A near-IR filter (F129/F158/F146) is optimally suited for this high-cadence SFR survey, as near-IR observations are crucial to detect more embedded sources and knots in stellar jets associated with mass accretion/ejection processes in YSOs. Contemporaneous time domain observations in a bluer filter (F062) would be instrumental in characterizing the detected YSOs in color-magnitude space. | Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | 2025 | |
| Dante Minniti | Universidad Andres Bello | Javier Alonso-Garcia, Roberto K. Saito, Maren Hempel | Homogeneous ages for the innermost Galactic globular clusters and search for missing globulars with the Roman GPS | Star clusters are important, as most stars are not born in isolation but in clusters within massive molecular clouds. Globular clusters (GCs) in particular are ideal laboratories containing stars formed more or less at the same time, from the same parent cloud, with homogeneous chemical composition (with minute spread due to multiple generations of stars), that evolved in the same environment because they share a common orbital path about the Galaxy, with negligible internal extinction, and located at the same distance. Also, the GCs are the oldest known objects in our Galaxy, and can therefore help us map the early history of assembly of the Milky Way (MW). Aside from their importance for the formation of the MW, GCs in particular are very relevant tools for different topics: Age of the Universe, Chemical evolution Universe, Stellar evolution, Galactic structure, Distance scale, Dynamical probes, Collisional systems, Interstellar medium, etc. We propose to determine GC ages homogeneously throughout the inner MW using the Galactic Plane Survey (GPS) of the Roman Space Telescope. We need deep images reaching 2-3 magnitudes below the main-sequence turn-off (Ks<21 mag) with the F129, F158, F213 passbands in order to make color-magnitude diagrams that would be fit with theoretical isochrones to determine the GC physical parameters, including the distances and ages (metallicities also, although most targets already have spectroscopic abundances). In addition, three filters are needed to make color-color diagrams in order to correct for any residual differential extinction within the fields. There are only a limited sample of Galactic GCs known, and every discovery of a new GC is a treasure. Here we advocate a contiguous coverage of an extended GPS area of the disk/bulge within -10deg < GL < +10deg, -10deg < GB < +10deg, in order to measure their ages and also to search for new GCs. According to the recent compilations of Bica et al. (2024, A&A), and Garro et al. (2024, A&A), there are N=64 GCs in this region, of which 33% are new discoveries made within the past 10 years (Figure). Many of these objects do not have measured ages, and for those ones with determined ages (e.g., from the HST), they are not consistently measured across different studies, and most have not been proper motion cleaned as the Roman GPS is capable of doing. If the coverage of the GPS is limited to -6 deg < GB < +6 deg, some important GCs would be excluded, namely: NGC6284, NGC6342, NGC6273, NGC6325, NGC6293, NGC6266, NGC6642, NGC6558, NGC6569, NGC6638, NGC6624, FSR0019*, Gran2*, FSR0009*, and Patchick99* (the objects marked with an asterisk are newly discovered GCs). Including these objects would allow to give a more complete picture of formation for our Galaxy by mapping the age gradient of the GC system. Excluding these objects mean that we lose about one third of the bulge GCs, and most importantly, this would bias the sample (for example because of the known presence of a metallicity gradient, that may be associated with an age gradient in the oldest population of the inner MW). There is also a huge discovery potential for new GCs, particularly low luminosity ones that are difficult to find from the ground due to field contamination and crowding. These problems would be mitigated by the high resolution and accurate proper motions provided by the Roman GPS. We estimate that extending the Roman GPS to |GB|<10 deg we may find 10-20 more GCs! (extrapolation made using the GC luminosity function and symmetry arguments). |
Galactic Plane Survey | stellar populations and the interstellar medium | Stellar populations, globular clusters, Galaxy formation, stellar evolution | 2025 |
| Tathagata Pal | NASA NPP Fellow at GSFC | Greg Mosby, Guy Worthy, Valentin Ivanov | Roman IR Stellar Spectral Library | Stellar spectral libraries are used throughout astronomy in extragalactic and stellar astronomy to study topics from galaxy evolution from integrated spectra to examining stellar radial velocities. Empirical libraries, based on observations as opposed to theoretical libraries, provide the most realistic basis to use in applications to observational data. Stellar libraries extending in near-IR are important for modelling mid to old age stellar populations. These populations contain evolved giant stars (AGB and TP-AGB) that contribute significantly to the near-IR luminosity of these populations. Thus, to properly model such a population we need empirical stellar libraries in near-IR. In the near infrared, there has been a relative lack of empirical stellar spectral libraries compared to optical wavelengths. APOGEE recently used its high resolution (R~22000) survey data to generate an empirical stellar spectral library in H-band from nearly 300,000 stars. Previous surveys from the ground (Pickles, IRTF, X-shooter, and Lancon & Wood) have generated spectral libraries from hundreds of stars and at lower resolution (R~200-10000). The main drawback of APOGEE stellar library is its very narrow wavelength coverage (1.52 - 1.69 um) whereas the other currently available near-IR stellar spectral libraries suffer from low number of stellar observations not sufficient to cover the parameter space ([Fe/H]-log(g)-Teff) comprehensively. Moreover, even high-S/N observations are subjected to systematic uncertainties from the imperfect telluric absorption removal. Observations with the Roman grism of stars in the Galaxy could be used to generate a space-based IR stellar spectral library from Y-band to H-band. The Roman grism will be able to observe within a wavelength range of 1.0 - 1.93 um with a moderate resolution of /600. Roman's measurements would lack Earth's atmospheric features and transmission gaps. And Roman's wide field of view might enable a sizable number and diversity of stellar targets. The slitless spectroscopy using Roman's grism will be able to collect spectral data for nearly 1000's of point sources in one pointing (this is made possible with 0.281 square degree field of view of Roman Wide Field Instrument). Roman's exposure time calculator shows that the exposure time required in order to achieve a S/N of 5 at 1.8 um for a star of apparent AB magnitude of 21.0 is about 4049 sec (for a zodiacal light level set at two times the minimum) . Also the current grism sensitivity shows an AB magnitude cut off of 20.8 at 1.8um for a 5-sigma detection limit for a 1-hour exposure time with zodiacal light background at twice the minimum intensity for a point source's emission line's integrated flux. Thus, ideally we would like to constraint ourselves within an AB magnitude of 20.0. Using the Besancon model, it is predicted that there will be around 10^7 stars within 2 degree galactic latitude either way from the galactic center (left panel of Figure 13 in GBTDS report) upto a AB magnitude of 20.0. For this pitch, we are more interested in regions of the sky away from the galactic center (as we are looking for fainter sources and they are hard to detect in a crowded field) both in terms of latitude and longitude. Another benefit of looking into the galactic halo (out of the galactic plane) is that we'll be able to see more stars with lower [Fe/H], significantly increasing the [Fe/H] coverage of the stellar library. Thus, with dedicated time of observation upto 3 weeks we should be able to observe at least 800,000 individual stars! This will give us a huge amount of stellar spectral data spanning a wide range in the parameter space. |
Galactic Plane Survey | stellar physics and stellar types, stellar populations and the interstellar medium | 2025 | |
| Roberto K. Saito | Universidade Federal de Santa Catarina - Brazil | Javier Alonso-García, Maren Hempel | Expanding the Roman observations of the Milky Way bulge | The proposed area discussed at the Roman Galactic Plane Workshop for the bulge observations is limited to |B|<6 deg and |L|<10 deg. Increasing the area to |B|<10 would bring scientific advantages in several areas, from studies on the solar system to extragalactic astrophysics, taking advantage of the Roman WFI unique capabilities: - Solar system: as the ecliptic crosses the Galactic bulge, the extension would increase the area over the ecliptic by ~70%, facilitating the search for faint solar system objects, including NEOs, MBAs, LJ5s and TNOs, increasing the census of these objects, especially at the detection limit of the current systems for monitoring minor bodies in the solar system. - Stellar Populations and Galactic Structure: the Galactic bulge is known to have a complex structure, with a classical bulge coexisting with an X-shape structure, as well as having a metallicity gradient and a non-uniform distribution of gas and dust. Expanding the area would make it possible to trace the X-shaped structure along its entire length, especially in the regions behind the bulge. It would allow the construction of metallicity and extinction maps for the whole bulge, including 3-D maps for the latter, which are currently limited to the foreground disk. - Star clusters: With the depth of the Roman observations, the projected area between 6<|B|<10 deg would cross the various Galactic components, allowing the discovery of new star clusters of different ages. The current distribution of clusters shows that a large number remain undetected, especially in Galactic quadrants I and IV. - Sagittarius dwarf galaxy: the region of the Sgr dSph is not included in the currently proposed observations. Despite the observations of surveys such as VVV and Gaia, we still lack a complete picture of the Sgr dSph stellar populations at low Galactic latitudes, which could be obtained by Roman. As well as tracing the core and stream of Sgr dSph more accurately, the observations could even allow the discovery of brown stars (or pairs of those) of extragalactic origin being accreted by the Milky Way. - Extragalactic studies: The number of Milky Way background galaxies discovered has increased in recent years due to the era of large infrared surveys, including the discovery of galaxy clusters in the Zone of Avoidance. Roman observations in the target region would increase the statistics of these objects for fainter galaxies (i.e. smaller or at higher redshifts sources) and even contribute to cosmological and dark matter studies. Finally, expanding to |B|<10 would increase the proposed bulge area by 160 sq deg, which considering an observation efficiency of 8 sq deg/hour and 3 filters, would increase the observation time by only ~60 hours, which is less than 10 percent of the planned Galactic survey. |
Galactic Plane Survey | solar system astronomy, stellar physics and stellar types, stellar populations and the interstellar medium, the intergalactic medium and the circumgalactic medium, Galactic structure | 2025 |