Science Goals

Explore the behavior of matter and energy in its most extreme environments

Cosmic rays, high-energy charged particles traveling at velocities that can approach the speed of light, are a rich potential probe of chemical and nuclear in the Universe. The majority of cosmic rays are atomic nuclei from hydrogen to the heaviest elements with energies spanning more than twelve orders of magnitude. In the low energy end, these cosmic rays are most likely accelerated in supernova remnants. Their elemental and isotopic composition probes nucleosynthesis, nuclear interactions with the interstellar medium, the distribution of freshly synthesized elements, and the mechanism of supernova explosions. At energies above roughly 1017 eV a different source dominates. The acceleration engines responsible for such extreme energies are not well understood, but at the highest energies, above about 6 × 1019 eV, the rapid energy loss resulting from interactions with the cosmic microwave background limits sources to within about 100 Mpc. Other cosmic ray components include electrons, positrons and antiprotons. While these are largely the result of interactions of nuclear cosmic rays with the ISM, they may have other origins. Positrons and electrons can be produced directly in astrophysical objects such as pulsars and deviations in their spectra can provide important insights into nearby sources. Cosmic ray particles may also be produced directly by the annihilation of dark matter candidates such as nutralinos and Kaluza-Klein particles. Details of the spectra of the resulting particles would therefore provide important constraints on the nature of the dark matter.

Program News

1 Jul 2014
NASA: Call for U.S. Scientists to serve on the ATHENA Science Study Team »  Details
30 Jun 2014
PCOS/PhysPAG Town Hall Meeting, Aug 19, 2014, agenda posted »  Details

Project News

Chandra News
22 Jul 2014
NASA's Chandra X-ray Observatory Celebrates 15th Anniversary » Details
Fermi News
22 Jul 2014
NASA's Fermi Finds A 'Transformer' Pulsar » Details
Planck News
23 Oct 2013
Last Command Sent to ESA's Planck Space Telescope
» Details
XMM-Newton News
11 Jul 2014
Bizarre Nearby Blast Mimics Universe's Most Ancient Stars » Details

Related News

NuSTAR News
19 Jun 2014
Swiftly Moving Gas Streamer Eclipses Supermassive Black Hole » Details
Suzaku News
30 Oct 2013
Suzaku Study Points to Early Cosmic 'Seeding' » Details
Swift News
19 Jun 2014
NASA's Swift Satellite Tallies Water Production of Mars-bound Comet » Details