Related papers: Fermi-LAT upper limits on gamma-ray emission from …
We present broadband (radio, optical, and X-ray) light curves and spectra of the afterglows of four long-duration gamma-ray bursts (GRBs 090323, 090328, 090902B, and 090926A) detected by the Gamma-Ray Burst Monitor (GBM) and Large Area…
Recent detections of GeV photons in a few GRBs by Fermi-LAT imply huge bulk Lorentz factors to avoid a large gamma gamma optical depth at high energy. Estimates can be as high as Gamma ~ 1000 in the most extreme cases. This puts severe…
We present the analysis of Fermi Large Area Telescope (LAT) $\gamma$-ray observations of HB~21 (G89.0+4.7). We detect significant $\gamma$-ray emission associated with the remnant: the flux >100 MeV is…
Locating the gamma-ray emission sites in blazar jets is a long-standing and highly controversial issue. We investigate jointly several constraints on the distance scale r and Lorentz factor Gamma of the gamma-ray emitting regions in…
The powerful wind-wind collision in massive star binaries creates a region of high temperature plasma and accelerates particles to relativistic energies. I briefly summarize the hydrodynamics of the wind-wind interaction and the…
Colliding winds of massive star binary systems are considered as potential sites of non-thermal high-energy photon production. This is motivated merely by the detection of synchrotron radio emission from the expected colliding wind…
Gamma-ray binaries are thought to be composed of a young pulsar in orbit around a massive O or Be star, with their gamma-ray emission powered by pulsar spindown. The number of such systems in our Galaxy is not known. We aim to estimate the…
According to radiative models, radio galaxies are predicted to produce gamma-rays from the earliest stages of their evolution onwards. The study of the high-energy emission from young radio sources is crucial for providing information on…
Context: Recent gamma-ray observations of young star clusters revealed that stellar wind termination shocks accelerate particles, with the energy reservoir provided by the mechanical power of massive-star winds. Aims: Our goal is to…
We report on a systematic investigation of the gamma-ray properties of 120 hard X-ray-selected Seyfert galaxies classified as `radio-quiet' objects, utilizing the three-year accumulation of Fermi-LAT data. Our sample of Seyfert galaxies is…
The Fermi Large Area Telescope (Fermi LAT) provides long term systematic monitoring observations of the gamma-ray emission from blazars. The variability properties and the correlation with other wavelength bands are important clues for the…
From the launch of the Fermi Gamma-ray Space Telescope to July 9, 2010, the Gamma-ray Burst Monitor (GBM) has detected 497 probable GRB events. Twenty-two of these satisfy the simultaneous requirements of an estimated burst direction within…
In March 2013, a flaring episode from the Crab Nebula lasting ~2 weeks was detected by the Fermi-LAT (Large Area Telescope on board the Fermi Gamma-ray Space Telescope). VERITAS provides simultaneous observations throughout this period.…
For more than one year the Fermi Large Area Telescope has been surveying the gamma-ray sky from 20 MeV to more than 300 GeV with unprecedented statistics and angular resolution. One of the key science targets of the Fermi mission is diffuse…
Gamma-ray loud X-ray binaries are binary systems that show non-thermal broadband emission from radio to gamma rays. If the system comprises a massive star and a young non-accreting pulsar, their winds will collide producing broadband…
The $\eta$ Carinae binary system is the first $\gamma$-ray binary ever observed which does not contain a compact object. The dense wind of the primary star shocks against the fast light wind coming from the companion star, creating the…
Since its successful launch in June 2008, the {\it Fermi} Gamma-ray Space Telescope has made important breakthroughs in the understanding of the Gamma-Ray Burst (GRB) phenomemon. The combination of the GBM and the LAT instruments onboard…
We perform a stringent search for precursor emission of short gamma-ray bursts (SGRBs) from the Fermi/GBM data and find 16 precursor events with $\gtrsim4.5\sigma$ significance. We find that the durations of the main SGRB emission ($T_{\rm…
The coexistence of Planck and Fermi satellites in orbit has enabled the exploration of the connection between the (sub-)millimeter and gamma-ray emission in a large sample of blazars. We find that the gamma-ray emission and the (sub-)mm…
The nature of the $\gamma$-ray emission from the \emph{Fermi} bubbles is unknown. Both hadronic and leptonic models have been formulated to explain the peculiar $\gamma$-ray signal observed by the Fermi-LAT between 0.1-500~GeV. If this…