Related papers: Isotropic diffuse and extragalactic $\gamma$-ray b…
The Fermi Gamma-ray Space Telescope has revealed a diffuse $\gamma$-ray background at energies from 0.1 GeV to 1 TeV, which can be separated into Galactic emission and an isotropic, extragalactic component. Previous efforts to understand…
We evaluate the contribution to the Isotropic Gamma-Ray Background (IGRB) coming from Radio Galaxies (RGs), the subclass of radio-loud Active Galactic Nuclei (AGN) with the highest misalignment from the line of sight (l.o.s.). Since only a…
We analyze the recently published Fermi-LAT diffuse gamma-ray measurements in the context of leptonically annihilating or decaying dark matter (DM) with the aim to explain simultaneously the isotropic diffuse gamma-ray and the PAMELA, Fermi…
The origin of the diffuse extragalactic, high-energy gamma-ray background (EGRB) filling the Universe remains unknown. The spectrum of this extragalactic radiation, as measured by the EGRET on-board CGRO, is well-fit by a power law across…
Origin of extragalactic gamma-ray background (EGRB) is still a matter of debate. EGRB can either have truly diffuse or unresolved discrete point sources origin. Majority of the Fermi and EGRET detected identified sources are blazar. So,…
The one-point function (i.e., the isotropic flux distribution) is a complementary method to (anisotropic) two-point correlations in searches for a gamma-ray dark matter annihilation signature. Using analytical models of structure formation…
For the first time, the Fermi-LAT measured the angular power spectrum (APS) of anisotropies in the diffuse gamma-ray background. The data is found to be broadly compatible with a model with contributions from the point sources in the 1-year…
Dark matter annihilation in Galactic substructure produces diffuse gamma-ray emission of remarkably constant intensity across the sky, and in general this signal dominates over the smooth halo signal at angles greater than a few tens of…
We study the origin of the extragalactic diffuse gamma-ray background using the data from the Fermi telescope. To estimate the background level, we count photons at high Galactic latitudes |b|>60 degrees. Subtracting photons associated to…
Measurement of the extragalactic background (EGBR) of diffuse gamma-rays is perhaps one of the most challenging tasks for future gamma-ray observatories, such as GLAST. This is because any determination will depend on accurate subtraction…
One way to understand the nonthermal history of the universe is by establishing the origins of the unresolved and truly diffuse extragalactic gamma rays. Dim blazars and radio/gamma galaxies certainly make an important contribution to the…
The origin of the cosmic gamma-ray background (CGB) is a longstanding mystery in high-energy astrophysics. Possible candidates include ordinary astrophysical objects such as unresolved blazars, as well as more exotic processes such as dark…
We study the capabilities of the Fermi-LAT instrument for identifying particle Dark Matter properties as mass, annihilation cross section and annihilation channels, with gamma-ray observations from the Galactic Center. For the potential…
If dark matter is composed of neutralinos, one of the most exciting prospects for its detection lies in observations of the gamma-ray radiation created in pair annihilations between neutralinos, a process that may contribute significantly…
The extragalactic dark matter (DM) annihilation signal depends on the product of the clumping factor, <\delta^2>, and the velocity-weighted annihilation cross section, \sigma v. This "clumping factor-\sigma v" degeneracy can be broken by…
We calculate the diffuse $\gamma$-ray emission due to the population of misaligned AGN (MAGN) unresolved by the Large Area Telescope (LAT) on the {\it Fermi} Gamma-ray Space Telescope ({\it Fermi}). A correlation between the $\gamma$-ray…
Decaying dark matter particles could be indirectly detected as an excess over a simple power law in the energy spectrum of the diffuse extragalactic gamma-ray background. Furthermore, since the Earth is not located at the center of the…
Radio-loud active galactic nuclei (AGN) are expected to contribute substantially to both the intensity and anisotropy of the isotropic gamma-ray background (IGRB). In turn, the measured properties of the IGRB can be used to constrain the…
We show that inverse Compton scattering of cosmic-microwave-background and starlight photons by cosmic-ray electrons in the interstellar and intergalactic space explains well the spectrum and intensity of the diffuse gamma-ray background…
Our understanding of the $\gamma$-ray sky has greatly advanced, yet studying the unresolved $\gamma$-ray background (UGRB) can unveil the nature of the faintest $\gamma$-ray source populations in the Universe. Statistical cross-correlations…