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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.


Program News and Announcements

31 May 2019
Dr. Thomas Zurbuchen, NASA SMD Associate Administrator, invites the science community to a live-streamed national colloquium on Wednesday, June 5, 2019 (4:00–6:00 pm EDT) on "Writing Successful Mission Proposals: Observations from NASA." To attend in person at the University of Colorado campus, please RSVP here. The live stream will be available here. For further details, please see the colloquium invitation. »  Details
17 May 2019
Following up on a Nov 2018 mission PI diversity workshop, the NASA Science Mission Directorate (SMD) is planning a number of exciting opportunities open to community participation, including a new website for potential PIs, pre-review mission panels to ensure diversity and reduce conflicts of interest, research proposal writing workshops at conferences and for PIs developing their first proposal, career development positions, and a presentation by SMD Associate Administrator Thomas H. Zurbuchen on proposal statistical analysis. Please see the Associate Administrator's full update here.
16 May 2019
June 1 2019 is the deadline for filling and submitting the technology gap submission form. We encourage members of the community to identify such gaps between today's state-of-the-art and what will be needed for missions identified by the 2010 Decadal Survey, the 2018 Astrophysics Implementation Plan, and/or the 30-year Astrophysics Road Map. Please see the Astrophysics Division Technologists letter for more details, including how to submit a gap.
25 March 2019
NASA HQ Astrophysics Division has created a task force to assess NASA's role in strategic optimization of Gravitational Wave Electromagnetic Counterpart (GW-EM) astrophysics. See the Terms of Reference for more details.
1 February 2019
Dr Terri Brandt confirmed as PCOS Chief Scientist.

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