Related papers: Diffuse Pionic Gamma-Ray Emission from Large Scale…
Fast radio bursts (FRBs) are one of the most exciting new mysteries of astrophysics. Their origin is still unknown, but recent observations seem to link them to soft gamma repeaters and, in particular, to magnetar giant flares (MGFs). The…
The large majority of EGRET point sources remain without an identified low-energy counterpart, and a large fraction of these sources are most likely extragalactic. Whatever the nature of the extragalactic EGRET unidentified sources, faint…
The cosmic gamma-ray background radiation is one of the most fundamental observables in the gamma-ray band. Although the origin of the cosmic gamma-ray background radiation has been a mystery for a long time, the Fermi gamma-ray space…
One of the most exciting discoveries of recent years is a pair of gigantic gamma-ray emission regions, the so-called Fermi bubbles, above and below the Galactic center. The bubbles, discovered by the Fermi space telescope, extend up to…
Current theories predict relativistic hadronic particle populations in clusters of galaxies in addition to the already observed relativistic leptons. In these scenarios hadronic interactions give rise to neutral pions which decay into…
Before the launch of the Fermi Gamma-ray Space Telescope there were only a handful of gamma-ray bursts (GRBs) detected at high energies (above 100 MeV), while several different suggestions have been made for possible high-energy emission…
Measurements of the diffuse extragalactic gamma-ray background (EGRB) are complicated by a strong Galactic foreground. Estimates of the EGRB flux and spectrum, obtained by modeling the Galactic emission, have produced a variety of…
Long Gamma-Ray Bursts (GRBs) are produced by ultra-relativistic jets launched from core collapse of massive stars. Most massive stars form in binaries and/or in star clusters, which means that there may be a significant external photon…
Statistical arguments show that the volume- and time-averaged kinetic power of GRBs and fireball transients (FTs) into an L* galaxy like the Milky Way is at the level of 10^40 ergs/s. This number, though with wide uncertainties related to…
The cosmic formation rate of long Gamma Ray Bursts (LGRBs) encodes the evolution, across cosmic times, of their progenitors' properties and of their environment. The LGRB formation rate and the luminosity function, with its redshift…
We report on a detailed investigation of the gamma-ray emission from 18 broad line radio galaxies (BLRGs) based on two years of Fermi Large Area Telescope (LAT) data. We confirm the previously reported detections of 3C 120 and 3C 111 in the…
Fast radio bursts (FRBs) are a recently discovered class of GHz-band, ms-duration, Jy-level-flux astrophysical transients, which origin is still a mystery. Exploring their gamma-ray counterpart is crucial for constraining their origin and…
Fermi LAT (Large Area Telescope) and GBM (Gamma ray Burst Monitor) observations of GRBs are briefly reviewed, keeping in mind EGRET expectations. Using gamma\gamma constraints on outflow Lorentz factors, leptonic models are pitted against…
We report the Fermi Large Area Telescope (Fermi-LAT) detection of the gamma-ray emission towards the young massive star cluster RSGC 1. Using the latest source catalog and diffuse background models, we found that the diffuse gamma-ray…
Recent observations of the diffuse Galactic \gr emission (DGE) by the {\it Fermi} Large Area Telescope ({\it Fermi}-LAT) have shown significant deviations, above a few GeV until about 100 GeV, from DGE models that use the GALPROP code for…
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…
The small angular scale fluctuations of the (on large scale) isotropic gamma-ray background (IGRB) carry information about the presence of unresolved source classes. A guaranteed contribution to the IGRB is expected from the unresolved…
The all-sky survey in high-energy gamma rays (E$>$30 MeV) carried out by the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton Gamma-Ray Observatory provides a unique opportunity to examine in detail the diffuse gamma-ray…
The presence of relativistic electrons within the diffuse gas phase of galaxy clusters is now well established, but their detailed origin remains unclear. Cosmic ray protons are also expected to accumulate during the formation of clusters…
Many different physical processes have been suggested to explain the prompt gamma-ray emission in gamma-ray bursts (GRBs). Although there are examples of both bursts with photospheric and synchrotron emission origins, these distinct…