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

22 Aug 2016
Call for Nominations to the Executive Committee of the Physics of the Cosmos Program Analysis Group (PhysPAG) »  [PDF]
28 July 2016
L3ST Interim Report now available »  [PDF]
14 July 2016
PCOS Newsletter for July 2016 now available »  [PDF]
14 June 2016
LISA Pathfinder First Results Announcements »  Details

Project News

Chandra News
30 Aug 2016
Record-breaking Galaxy Cluster Discovered » Details
Fermi News
12 Aug 2016
NASA's Fermi Mission Expands its Search for Dark Matter » Details
Planck News
13 Aug 2016
First Stars Formed Even Later Than Previously Thought
» Details
XMM-Newton News
29 Aug 2016
XMM-Newton Reveals the Milky Way's Explosive Past » Details

Related News

Hitomi News
6 July 2016
Hitomi Mission Charts Hot Winds of a Galaxy Cluster for the First Time »  Details
NuSTAR News
28 Jul 2016
Chorus of Black Holes Sings in X-Rays » Details
Suzaku News
26 Aug 2015
X-ray Astronomy Satellite "Suzaku" Completes Scientific Mission » Details
Swift News
8 Sep 2016
Young Magnetar Likely the Slowest Pulsar Ever Detected » Details