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Seminars»07.12.2017 - Hasan Yüksel : ASTROPHYSICAL AND EXOTIC ORIGINS OF COSMOLOGICAL HIGH ENERGY PARTICLES

07.12.2017 - Hasan Yüksel : ASTROPHYSICAL AND EXOTIC ORIGINS OF COSMOLOGICAL HIGH ENERGY PARTICLES

ASTROPHYSICAL AND EXOTIC ORIGINS OF COSMOLOGICAL HIGH ENERGY PARTICLES

Hasan Yüksel
MSGSÜ Department of Physics
07 December 2017, Thursday, 14:40
Cavid Erginsoy Seminar Room, Physics Department, 3rd floor

Abstract: It is expected that both astrophysical sources (such as supernova remnants and pulsars) and exotic sources (such as self-annihilation or decay of dark matter particles) produce variety of cosmic-ray particles.  The spectra of cosmic electrons and positrons should have contributions from known sources such as particles accelerated in supernova remnants and from interactions of cosmic and interstellar protons.  Any evidence for an additional component in their spectra, as reported in recent observations, hints a new phenomenon. First, I will dicuss the implications of the detection of extended, multi-TeV gamma-ray emission from Geminga pulsar wind nebula, which reveals the existence of an ancient / nearby cosmic ray accelerators that can also account for the observed excess. Alternatively these excess particles might be produced through dark matter interactions in our Galaxy.  Dark matter, originally proposed by Zwicky to explain the mass to light ratio of alaxy clusters, still evades revealing its true identity. Many dark matter candidates have been proposed, spanning many orders of magnitude in mass.  Next, I will discuss prospects of detecting dark matter indirectly through either self-annihilation or decay products, and, present corresponding general upper bounds on total self-annihilation cross section or lifetime.  As an example, I will focus on two interesting scenarios: dark matter models associated with 0.511 MeV positron annihilation line from the center of our Galaxy and sterile neutrinos as warm dark matter candidates.