Conveners
Extragalactic diffuse & EBL II
- Seth Digel (KIPAC/SLAC)
The main tools typically used to investigate the nature of the extragalactic gamma-ray background (EGB) are its energy spectrum and population studies of resolved point sources.
However, a larger amount of information is contained in the full gamma-ray maps, and this can be exploited to further push the study of the EGB.
This information can be encoded into different observables like the...
The Extragalactic Background Light (EBL) absorbs gamma-rays (γγ->e-e+) and leaves a characteristic imprint in the spectra of high energy blazars. Utilizing the new Fermi-LAT measurement of the gamma-ray optical depth at 0<z<3, we reconstruct the detailed build-up of the EBL over cosmic time in a model-independent way. We use an MCMC approach to determine the instantaneous luminosity density of...
Relying on the first 104 months of Fermi-LAT Pass 8 data, using detailed Monte Carlo simulations, we obtained the most sensitive measurement of the source count distribution of blazars above 100 MeV. The result shows, with high statistical significance, the presence of a break in the distribution at low fluxes. From this, we provide a precise measurement of the contribution of blazars to the...
Recent results on the Extragalactic Background Light (EBL) intensity obtained from a combined likelihood analysis of blazar spectra detected by the MAGIC telescopes are reported. The EBL is the optical-infrared diffuse background light accumulated during galaxy evolution, directly and/or reprocessed by dust, which provides unique information about the history of galaxy formation. The low...
The Extragalactic gamma-ray Emission (EGB) is constituted by two essential parts: resolved gamma-ray sources, point-like or extended, and an isotropic component. Once the formers have been excluded (masked or subtracted), what remains is the latter component, called Unresolved Gamma-Ray Background (UGRB), which, at a deeper level, is not truly isotropic and includes contribution from...
The extragalactic background light (EBL) is a fundamental cosmological observable of our universe, allowing insight into the history of star formation within our universe. Extending between 0.1 - 1000 $\mu$m, it is the UV to near-IR that is of interest in high and very high energy astronomy, where EBL photons interact via pair production to leave a visible imprint in the spectra of distant...
The Fermi-LAT has confirmed and measured with unprecedent precision the extragalactic gamma-ray background (EGB), which is the sum of the flux of cataloged sources and the Isotropic diffuse gamma-ray background (IGRB). The IGRB is a highly-isotropic component on angular scales larger than 1 degree and whose composition is thought to be dominated by unresolved sources, i.e., sources that are...
