Present PositionDirector, Astrophysics Science Division (Previously called Exploration of the Universe Division)Director of the HEASARC Chief Scientist for the Beyond Einstein Program Suzaku Project Scientist Constellation-X Project Scientist Brief BioAstrophysicist at the NASA Goddard Space Flight Center (since November 1990).Previous Appointments
Professional Societies
Educational BackgroundDoctor of PhilosophyUniversity College London, 1977Bachelor of Science University of Leicester, 1973 Research InterestsI have been involved in X-ray astronomy for all of my research career from 1973 to the present time. This interval covers a large part of the modern history of the field, where satellite observatories have been used to study cosmic X-ray sources. The topic of my 1977 Phd thesis is "The Variability of Several Galactic X-ray Sources" and included the study of X-ray binaries using data obtained with the UCL/MSSL instrument on Copernicus and the Experiment C on Ariel V and resulted in the discovery of many new X-ray pulsars with periods of several hundred seconds.Following this my research continued utilizing the X-ray astronomy missions HEAO-1, the Einstein (HEAO-2) Observatory, EXOSAT, ROSAT and ASCA as either an instrument team member or as part of the science data center. I have continued to pursue my original interest in X-ray binaries and has led to many interesting results including: the first observational evidence for an accretion disk coronae, the determination of orbital periods in low mass X-ray binaries, the classification of black hole candidates based on X-ray spectra, several detailed studies of X-ray pulsars, and the discovery of iron line emission from low mass X-ray binaries. In addition I have also investigated the properties of stellar coronae from nearby active stars. A major result of this work has been to show the existence of at least two dominant temperature emission regions in these systems. The most recent ASCA results have revealed that the line emission from these systems is weaker than expected, perhaps suggesting anomalously low abundances. In 1994 I have lead a cataloging effort based on the ROSAT archival data. This catalog contains more than 50,000 new X-ray sources. By using global spectral and time variability indicators the catalog is revealing many new interesting objects including nearby flare stars, cataclysmic variables, BL Lac objects and AGN. Most recent projects include the discovery of jets from a LMRXB in quiescence using XMM data and a second source in a galactic Globular Cluster using Chandra data and a theoretical investigation of the cosmic star formation rate using X-ray data. Current ProjectsSince 2005 I have been the Director of the Astrophyiscs Science Division at the Goddard Space Fligth Center. This Division has about 300 scientists, engineers and support staff. The Division provides Project Scientists for NASA projects for which GSFC has responsibility, develops instruments and undertakes research in submm, IR, Optical, UV, X-ray, Gamma-ray, Cosmic ray and Gravitational Wave astrophysics. I am currently Project Scientist for the Constellation-X and Astro-E2 missions. Since 2000 I have been chief of the Laboratory for High Energy Astrophysics at Goddard Space Flight Center.From 2000 to 2005 I was the Chief of the Lab for High Energy Astrophysics, at GSFC. This lab was responsible for Cosmic Rays, Gamme rays and X-ray Astronomy research at GSFC. Between 1993 and 2000 I was head of the X-ray Astrophysics Branch and of the Office for Guest Investigator Programs, OGIP in the Laboratory for High Energy Astrophysics at NASA's Goddard Space Flight Center. The X-ray branch is responsible for many flight programs including two instruments to be flown on Astro-E, MOXE, the ongoing RXTE mission, and technology development for future missions such as Constellation-X. The branch contains about 15 civil servants, many of whom are project scientists for NASA missions. The OGIP administers the High Energy Astrophysics Science Archive Research Center, HEASARC (of which I am the director), the ROSAT Guest Observer Facility, the ASCA and Astro-E Guest Observer Facilities and the GRO Science Support Center. The total number of staff in this office is of order 50 with a 30/70 mix of scientists and programmers. The prime function of the OGIP is to direct NASA's guest observer program in high energy astrophysics for the ROSAT, ASCA, GRO and XTE projects. As head of this office and diretor of the HEASARC I lead the overall programmatic activities and several major research projects. The HEASARC forms a crucial core to the OGIP mission by providing a multimission infrastructure. The HEASARC was created in November 1990 and was established under my leadership. The HEASARC activities include restoration of data from older missions (e.g. EXOSAT, Einstein and HEAO-1), remote access to the archive, analysis software and providing user support. Between 1990 and 1993 I was the deputy project scientist for the the ASCA (Astro-D) mission (launched in February 1993), with particular responsibility for the ASCA Guest Observer Facility at GSFC. This facility supports NASA's participation in the ASCA program including: providing data analysis software, distributing data to US and European guest observers, liasing with Japanese scientists at ISAS and providing expertise in the analysis of ASCA data. At the launch of ASCA in 1993, I assumed the full project scientist responsibility. Between 1986 and 1990 I had a similar responsibility as the EXOSAT project scientist. In this role I was responsible for managing the EXOSAT post-operations phase. This effort resulted in the creation of the EXOSAT database, an on-line data archive containing results and data products (i.e. spectra, images lightcurves) from the EXOSAT mission. The EXOSAT database became operational in April 1989, and was one of the pioneer on-line astronomical database systems. It is now in use by several other institutions including the HEASARC, the University of Leicester, and MPE. Prior to this as the EXOSAT Observatory Senior Observatory Scientist (1982-1986) I was responsible for managing the scientific operations center of the EXOSAT mission at ESOC. I was also responsible for calibration, operation and analysis software for the gas scintillation proportional counter on EXOSAT. During my research activities at the Goddard Space Flight Center (1978-1982) I was a member of the Einstein solid state spectrometer instrument team. As part of the research effort my duties included writing the analysis software and participating in the calibration of the instrument. Prior to this at MSSL/UCL I spent several intervals at GSFC as the resident astronomer for the UCL/MSSL X-ray telescope on OAO-3. Selected PublicationsThe INTEGRAL Science Data Centre (ISDC),A.& A.,2003, 411,L53-L57 Courvoisier, T. J.-L., Walter, R., Beckmann, V., Dean, A. J., Dubath, P., Hudec, R., Kretschmar, P., Mereghetti, S., Montmerle, T., Mowlavi, N., Paltani, S., Preite Martinez, A., Produit, N., Staubert, R., Strong, A. W., Swings, J.-P.,Westergaard, N. J., White, N., Winkler, C., Zdziarski, A. A. An XMM-Newton Observation of 4U 1755-33 in Quiescence: Evidence of
a Fossil X-Ray Jet The Discovery of a Second Luminous Low-Mass X-Ray Binary in the
Globular Cluster M15 X-Ray Probes of Cosmic Star Formation History The Consequences of the Cosmic Star Formation Rate: X-Ray Number
Counts Correlations between Spectral Properties and Spin-down Rate in
Soft Gamma-Ray Repeaters Multiwaveband studies of the hard ROSAT SMC transient 1WGA
J0053.8-7226: a new X-ray pulsar The XMM-Newton Serendipitous Survey. I. The role of XMM-Newton
Survey Science Centre Imaging Black Hole, Nature, 2000, 407,146, White, N.E. Coronal Structure and Abundances of Capella from Simultaneous
EUVE and ASCA Spectroscopy ASCA Observation of the Dipping X-Ray Source XB 1916-053 BeppoSAX monitoring of the ``anomalous'' X-ray pulsar 4U 0142+61}
SAX
monitoring of the ``anomalous'' X-ray pulsar 4U 0142+61 X-Ray Spectroscopy of Rapidly Rotating, Late-Type Dwarf Stars
ApJ (1999) 512, 874. Alpha Centauri: coronal temperature structure and abundances from
ASCA Observations Low-Mass
X-Ray Binaries, Millisecond Radio Pulsars, and the Cosmic Star
Formation Rate The
discovery of 12-min X-ray pulsations from 1WGA J1958.2+3232 On
the Amplitude of Burst Oscillations in 4U 1636-54: Evidence for
Nuclear-powered Pulsars X-ray
observations of the slowest known Be/X-ray pulsars RXJ0146.9+6121
and X Persei Millisecond
X-Ray Pulsars in Low-mass X-Ray Binaries The
Discovery of 8.9 Second Pulsations from the Variable
X-Ray Source 2E 0050.1-7247 in the Small Magellanic Cloud Discovery
of Kilohertz Quasi-periodic Oscillations from 4U 1820-303
with Rossi X-Ray Timing Explorer The
Nature of the ``6 Second'' and Related X-Ray Pulsars:
Evolutionary and Dynamical Considerations Archival
observations of the ultra-soft X-ray transient 4U 1630-47. The
Discovery of 13 Second X-Ray Pulsations from the Hydrogen-depleted
Subdwarf O6 Star Binary HD 49798. The
X-ray evidence that the 51 Peg companion is a planet, Emission Measure Analysis Methods: The Corona of AR Lacertae
Revisited, The
Galactic Distribution of Black Hole Candidates in
Low Mass X-ray Binary Systems, Corona(e)
of AR Lacertae. II. The Spatial Structure Kilohertz
Quasi-periodic Intensity Oscillations from 4U 1636-536 ASCA Observations of the Iron Line Structure in Cygnus X-1, The
Spectrum of the 8.7s X-ray Pulsar 4U0142+61, Corona(e) of AR Lacertae. I. The Temperature and Abundance
Distribution, Orbital period changes of Cygnus X-3, Neon Line Emission in the X-Ray Spectrum of the Pulsar 4U 1626-67, The Softest X-ray Sources in the ROSAT Pointed Catalog: WGACAT, A New Cataclysmic Variable: WGA J1047.1+6335, Periodic Outbursts from the Ultrasoft X-ray Transient 4U1630-47, The Galactic Distribution of Low-Mass X-ray Binaries, A study of coronal X-ray emission from short-period Algol binaries, RX
J0045.4+4154: A Recurrent Supersoft X-ray Transient in M31, The EXOSAT GSPC iron line catalog, An ASCA observation of the Castor system, ASCA X-ray Spectra of the Active Single Stars Beta Ceti and PI(1)
Ursae Majoris, ASCA observations of the coronal emission of Algol, The fluorescence-dominated X-ray spectrum of the spiral galaxy NGC
6552, Discovery of the Double Doppler-Shifted Emission-Line Systems in
the X-ray Spectrum of SS 433, An ASCA Observation of One Orbital Cycle of AR Lacertae, Resolving the Cygnus X-3 Iron K Line, Accretion disk corona line emission from X0614+091, A ROSAT observation of Delta Orionis A, The luminosity dependence of the X-ray spectrum of the transient
42 second pulsar EXO 2030+375, The X-ray time variability and spectrum of Gamma Cassiopeiae (X
0053+604), The discovery and properties of the ultra-soft X-ray transient EXO
1846-031, The discovery of an X-ray burst and a study of aperiodic
variability from SMC X-1, A study of the flaring and quiescent X-ray and UV emission from II
Pegasi, The X-ray Absorption spectrum of Vela X-1, The X-ray orbital lightcurve of TY Pyx: a 3.2-day eclipsing RS CVn
system, X-ray Eclipse Mapping of AR Lacertae, X-ray Spectroscopy of the Ultrasoft Transient 4U 1543-47, An EXOSAT X-ray Observation of one orbital cycle of 4U1700-37/HD
153919, Iron K lines from low-mass X-ray binaries, X-ray Fluorescence from the inner disk in Cygnus X-1, The transient 42 second X-ray pulsar EXO2030+375, II. The
Luminosity Dependence of the Pulse Profile, The Transient 42 second X-ray Pulsar EXO 2030+375, I. The
Discovery and the Luminosity Dependence of the Pulse Period Variations,
A combined radio and X-ray observation of Algol, EXOSAT Observations of the Cassiopeia A Supernova Remnant, An EXOSAT Observation of CTB80, Simultaneous X-ray and radio observations of GX 13+1, Quasi-periodic Oscillations in the X-ray Flux of the Rapid Burster
(MXB1730-335), X-ray observations of the 50-min dipping source XB1916-053, EXOSAT Observations of Coronal X-ray emission from the Young K
Dwarf AB Doradus (= HD36705), The Radius of a Magnetosphere in the Radiation Pressure Dominated
region of an Accretion Disk, The Spin Histories of PSR1821-24 in M28 and PSR1951+32 in CTB80, Rotational Modulation and Flares on RS CVn and BY Dra systems, The X-ray Spectral Properties of Accretion Disks in X-ray Binaries, An EXOSAT Observation of the Bursting X-ray Transient 4U1608-52, EXOSAT Observations of the 1983 Outburst of the Rapid Burster: A
New Mode of Behaviour, The Properties of Bursts With Short Recurrence Times from the
Transient X-ray Source EXO0748-676, Intensity and Source State Dependance of the Quasi-periodic
Oscillations in Scorpius X-1, The Discovery of 15-30 Hertz Quasi-periodic Oscillations in the
X-ray Flux of 4U1820-30, EXOSAT Observations of Double-peaked Bursts with Radius Expansion
from 4U/MXB1820-30, The Discovery of 7 and 24-28Hz Quasi-periodic Oscillations in the
X-ray Flux of GX 17+2 (4U1813-17), The Discovery of a 685s Orbital Period from the X-ray Source
4U1820-30 in the Globular Cluster NGC 6624, An EXOSAT Observation of 1.5 Orbital Cycles of the 0.7 day Short
Period RS CVn System ER Vul, A 25 min Modulation from the Vicinity of the Unusually Soft X-ray
Source X0142+614, Intermittent Stellar Wind Accretion and the Long-term Activity of
Population I Binary Systems Containing an X-ray Pulsar, A Study of the Continuum and Iron K-line Emission from Low-mass
X-ray Binaries, An EXOSAT Observation of Quiscent and Flare Coronal X-ray Emission
from Algol, Orbital Elements of the Binary X-ray Pulsar GX301-2, H1504+65: An Extraordinarily Hot Compact Star Devoid of Hydrogen
and Helium, Bimodal quasi-oscillatory and spectral behaviour in Scorpius X-1, X-rays from the Magnetic White Dwarf PG 1658+441, A search for X-ray periodicities in 4U1700-37, The bursting behaviour of the transient X-ray burst source EXO
0748-676: A Dependance between the X-ray Burst Properties and the
Strength of the Persistent Emission, The Discovery of 3.8 hour Periodic Intensity Dips and Eclipses
from the Transient Low-mass X-ray Binary EXO 0748-676, The Evolution of the 1984 Outburst of the Transient X-ray Source
4U1630-47, Simultaneous X-ray and Infrared Observations of Cygnus X-3, The identification of H2311+77 with HD220140: A probable RS CVn, An Extended X-ray Low State from Hercules X-1, The Discovery of Low-level Iron K line Emission from Cyg X-1, The Discovery of 4.4 Second X-ray Pulsations from the Rapidly
Variable X-ray Transient V0332+53, Simultaneous X-ray and Optical Observations of the X-ray Dip
Source X1755-338, EXOSAT Observations of Broad Iron K Line Emission from Sco X-1, The 41.5 day Binary X-ray Pulsar 4U1223-62 (GX301-2), New Evidence on the Nature of the Neutron Star and Accretion Flow
in Vela X-1 from Pulse Timing Observations, Evidence for 4.4 hour periodic dips in the X-ray flux from
4U1755-33, The Unusually Soft X-ray Spectrum of LMC X-3, X-ray Spectral Signatures of Accreting Black Holes, X-ray Observations of X Persei, MXB1916-053/4U1915-05: Burst Properties and Constraints on a 50
min Binary Secondary, Optical and X-ray Observations of 2S0921-630, Accretion Powered X-ray Pulsars, An X-ray Survey of Nine Algol Systems, The X-ray Absorption Spectrum of 4U1700-37 and its Implications
for the Stellar Wind of the Companion HD153919, X-ray Properties of the Be/X-ray System 2S0114+650=LSI +65 010, Two Component X-ray Spectrum from SMC X-1, A Comparison of the X-ray Properties of X Persei and Gamma Cas, Accretion Disk Coronae, Einstein Observatory Pulse-Phase Spectroscopy of Hercules
X-1, The Anomalous X-ray Spectrum of Vela X-1, The Discovery of 50-min Periodic Absorption Events from 4U1916-05, The 805-s X-ray Pulsar H2252-035, A 5.57-hr Modulation of the X-ray Flux from 4U1822-37, Two Component X-ray Emission from RS CVn Binaries, An 81-minute Modulation of the X-ray Flux from 2A0311-227, Discovery of X-ray Emission from the RS CVn Binary Sigma Cor Bor, 4U1626-67: A prograde Spinning X-ray Pulsar in a 2500s Binary
Orbit, The Discovery of "Sco X-1 type"; Behaviour from the X-ray Burster
4U1735-44, A 5.57hr Modulation in the Optical Counterpart of 2S182-371, An Optical Burst from the Star Identified with the X-ray Source
2S1254-690, X-ray and Optical Observations of Correlated Flares in Sco X-1, X-ray Observations of Algol, X-ray and uv Spectroscopy of Cygnus X-1 = HD226868, The X-ray Pulsars 4U1145-61 and 1E1145.1-6141, X-ray Spectrum of Kepler's Supernova Remnant, Elemental Abundances in a Type I Supernova Remnant, HEAO 1 Observations of X-ray Emission from Flares on DMe Stars, Discovery of 38.22s X-ray Pulsations from the Vicinity of
OAO1653-40, Pulse Phase Spectroscopy of Her X-1, X-ray Line Emission from Capella, The X-ray Spectrum of Cas A Measured with the Einstein SSS, HEAO 1 Observations of the X-ray Pulsar 4U1626-67, Centaurus X-3, Two X-ray periodicities from the Vicinity of 4U1145-61, An X-ray Outburst from the RS CVn Binary HR1099, The Binary X-ray Pulsar 3U1223-62, The Recurrent X-ray Transient A0538-66, The Discovery of the Eclipsing Nature of LMC X-4, The Variability of MXB1730-335, X-ray and Optical Observations of the variability of Vela X-1
(3U0900-40), Searches for Correlated X-ray and Radio Emission from X-ray Burst
Sources, X-ray and Radio Observations of GX17+2 and GX13+1, Photometry of Slow Pulsars II. The 13.9 minute period of X Persei, An Increase in the X-ray Absorption of NGC4151, Optical and Infrared and Optical Observatons of NGC6624, Evidence for a 581 day Modulation in the Pulse Period of 3U0352+30, Discovery of Two Periodic X-ray Pulsators, A Study of Four Sources with Properties similar to Sco X-1, Observations of X-ray Bursts from the Vicinity of 3U1727-33, Periodic Behaviour of the X-ray Flux from the region near
3U1727-33, Infrared and X-ray Observations of the Decline of A0620-00, Periodic Modulation of Three Galactic X-ray Sources, X-ray Emission from Gamma Cas, The Interstellar Medium in the Line of Sight to X Per and
3U0352+30, The X-ray Behaviour of 3U0352+30 (X Per), X-ray and Optical Observations of Sco X-1, Invited ReviewsReview papers and Talks (not a complete list) The
ROSAT WGACAT Variable Sources, X-ray
Observations of Accretion Disks, Accretion
Disk Coronae, Stella
X-ray Spectroscopy with ASCA, ASCA Observations of Stars, EXOSAT EUV Observations, X-ray binaries Astronomy with EXOSAT, The EXOSAT Observatory, X-ray Spectral Formation in Low Mass X-ray Binaries, The Orbital Periods of the Low Mass X-ray Binaries, The Spectra of X-ray Transients, The Observered Properties of X-ray Pulsars, Nature - News and Views ArticlesSources of variable oscillations, Spin-up changes to spin-down. Popular MagazinesNew Wave Pulsars,
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