NBIA Seminar: Hannes-S. Zechlin – Niels Bohr Institute - University of Copenhagen

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NBIA Seminar: Hannes-S. Zechlin

(INFN, Turin)

Unveiling the unresolved extragalactic gamma-ray sky

The total gamma-ray emission observed in the sky with energies ranging from a few MeV up to a few hundred TeV is composed of two major components: gamma-ray foreground emission produced in our Galaxy, and the extragalactic gamma-ray background (EGB) that comprises point sources and an extragalactic diffuse isotropic component, the IGRB. Presumably, at least a part of the IGRB originates from an unresolved component of gamma-ray sources, which currently represent a major research topic in gamma-ray astrophysics. While the classical approach of EGB decomposition manifests in combined spectral fits of individual contributions, statistical methods have recently been proven to provide an even more sensitive observable. After a brief introduction to the nature of the gamma-ray sky, I will summarize recent attempts of using 1-point photon counts statistics for decomposing the EGB detected with Fermi-LAT, focusing on point-source contributions and the diffuse isotropic background contribution. Furthermore, I will generalize the analysis to incorporate a potential contribution from, e.g., annihilating dark matter or other new physics components.