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Astrophsyics

PhysCOS 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.


NASA Missions Study What May Be a 1-In-10,000-Year
Gamma-ray Burst

On Sunday, Oct. 9, 2022, a pulse of intense radiation swept through the solar system so exceptional that astronomers quickly dubbed it the BOAT – the brightest of all time. The source was a gamma-ray burst (GRB), the most powerful class of explosions in the universe. Read more.


PhysCOS News

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Program News and Announcements

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  • 23 March
    Physics of the Cosmos Activities at HEAD 2023 »  Details.
    23 March
    High Energy X-ray Probe Splinter Session at HEAD 2023 »  Details.
    23 March
    STAR-X Special Community Session at HEAD Meeting in Hawaii, 28 March 2023 »  Details.
    23 March
    ROSES-22: Astrophysics Decadal Survey Precursor Science Proposal Due Date Delay »  Details.
    23 March
    National Academies’ Space Science Week 28–29 March 2023 »  Details.
    23 March
    NASA Astrophysics Advisory Committee Spring Meeting 29–30 March 2023 »  Details.
    21 March
    Science Mission Directorate Budget Community Town Hall 23 March 2023 »  Details.
    21 March
    NOIRLab Call for Proposals for Semester 2023B, Including NN-EXPLORE Proposals »  Details.
    21 March
    Call for Proposals for the NASA Infrared Telescope Facility »  Details.
    21 March
    Arcus Probe Community Science Meeting 4-5 May »  Details.
    21 March
    NASA SMD Seeking Volunteer Reviewers for Research Proposals »  Details.
    6 March
    First COSI Data Challenge Released »  Details.
    6 March
    Stellar Intensity Interferometry Workshop 22–24 May 2023 »  Details.
    6 March
    Habitable Worlds Observatory hybrid workshop 8–10 August 2023 »  Details.
    1 March
    The AGN Vision Series »  Details.
    1 March
    ROSES-23 Released »  Details.
    7 February
    NASA Astrophysics Division Statement of Principles »  Details.
    7 February
    Minority University Research and Education Project (MUREP) Women’s Colleges and Universities (MUREP WCU) »  Details.
    25 January
    Upcoming Student/Postdoc Opportunities at NASA »  Details.
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