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National Aeronautics and Space Administration

Goddard Space Flight Center

Astrophysics Science Division | Sciences and Exploration

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ARCADE Science

ARCADE (Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission) is a high altitude balloon payload designed to study the early universe. It measures the frequency spectrum of the Cosmic Microwave Background (CMB) at centimeter wavelengths, to search for signals from the first stars to form after the Big Bang. It will address the following science goals:

Formation of Structure Observe the formation of structure from the first stars and galaxies

Particle Decay Search for particle physics relics from the Big Bang

Milky Way 408 MHz map Understand the large-scale structure and energetics of our Galaxy

Modern cosmology is based on the Hot Big Bang model, which traces the universe back in time over 13 billion years to an epoch when the Universe was vastly smaller and hotter than it is today.

Universe then and now Heat from the Big Bang still permeates the Universe today, and can be observed as a faint glow of microwaves from deep space. Imbedded within this Cosmic Microwave Background is a fossil record of the very early universe.
CMB and Cosmology The pattern of hot and cold spots in the microwave background (anisotropy) records the spatial distribution of matter and energy in the early universe. It encodes the dynamics and basic structure of the universe -- how fast the universe is expanding, how much matter it contains, and what types of matter. By contrast, the distribution of these microwaves into different wavelengths (its spectrum) records the energetics of the early universe. In essence, the spectrum tells us if any "Little Bangs" followed the Big Bang. ARCADE measures the spectrum of diffuse emission from deep space. Data from this mission will help determine how and when the first stars and galaxies formed, and whether exotic particles exist.

ARCADE will measure the heating of the universe by the first stars and galaxies to form after the Big Bang. It will also search for the signal of relic decays or annilhilation. ARCADE will measure distortions from a blackbody spectrum to limits
Free-Free Emission: Y_ff < 10^{-6} Chemical Potential: mu < 2 x 10^{-5}