• social media
    • facebook
    • twitter
    • youtube
    • flickr
    • instagram
    • googleplus
Astrophsyics

PCOS 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 the only direct probe of chemical composition and nuclearsynthesis 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. Cosmic rays with energies below and just above the so-called "knee" in the middle of this energy range are most likely accelerated in supernova remnants. Their elemental and isotopic composition probes nucleosynthesis, nuclear interactions in the interstellar medium, the distribution of freshly synthesized elements, global Galactic properties, the mechanisms of supernova explosions, and particle acceleration in supernova shocks. 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 6 x 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. Electrons are quite abundant and can be accelerated in many different types of sources, while positrons and antiprotons are largely the result of interactions of nuclear cosmic rays with the ISM but may also have other origins. Positrons as well as 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 in the annihilation of dark matter candidate particles such as, e.g., WIMPs, neutralinos, and Kaluza-Klein particles. Details of the spectra and composition of the resulting particles therefore provide important insights into the physics of particle accelerators and properties of the interstellar and/or intergalactic medium, and provide important constraints on the nature of the dark matter.



PCOS News

Program News and Announcements

20 December 2018
LISA Preparatory Science 2018 (LPS) proposals have been selected! »  Full details
17 December 2018
NASA HQ has publicly posted an updated Astrophysics Implementation Plan (AIP), detailing progress made by NASA's Astrophysics Division in implementing the 2010 Decadal recommendations since the previous update in 2016. Please see »  full details
29 November 2018
The National Academies has released updated information about the 2020 Decadal Survey call for Community Science White Papers. They are now due 7 January–19 February 2019. See here for further instructions. Further, it is our pleasure to announce that the President of the National Academy of Sciences Marcia McNutt has appointed Dr. Fiona Harrison and Dr. Robert Kennicutt, Jr. to serve as co-chairs of the Astronomy and Astrophysics Decadal Survey committee.
19 November 2018
We would like to welcome our two new PhysPAG EC members, starting in Dec 2018. We extend our thanks to the three departing EC members.
1 June 2018
MMA SAG analyzing the benefits of multimessenger observations made possible by NASA observatories in the 2020 decade and beyond launched! Join the kickoff telecon Friday, 8 June, and sign up today! »  Full details

Project News

Related News


Links

NASA logo
  • NASA Official: Phil Newman
  • Web Curator: Pat Tyler
Goddard Space Flight Center
privacy