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

3 Jan 2015
PhysPAG Activities at the 225th AAS Meeting, 4-7 Jan 2015 »  [Agenda]
13 Nov 2014
NASA issues second Dear Colleague Letter for community participation in the Athena Science Study Team Working Groups »  [PDF]
1 Oct 2014
2014 Program Annual Technology Report (PATR) now available »  [PDF]

Project News

Chandra News
26 Mar 2015
NASA's Hubble, Chandra Find Clues that May Help Identify Dark Matter » Details
Fermi News
9 Jan 2015
Third Catalog of Fermi-LAT Sources Released » Details
Planck News
10 Feb 2015
Planck: Gravitational Waves Remain Elusive
» Details
XMM-Newton News
19 Feb 2015
Widespread wind from black hole can shape star formation » Details

Related News

NuSTAR News
19 Feb 2015
NASA, ESA Telescopes Give Shape to Furious Black Hole Winds » Details
Suzaku News
2 Apr 2015
Suzaku Studies Supernova 'Crime Scene,' Shows a Single White Dwarf to Blame » Details
Swift News
20 Nov 2014
NASA's Swift Satellite Marks 10 Years of Game-changing Astrophysics » Details