Related papers: Seyfert 2 galaxies in the GeV band: jets and starb…
The Fermi/LAT collaboration recently reported the detection of starburt galaxies in the high energy gamma-ray domain, as well as radio-loud narrow-line Seyfert 1 objects. Motivated by the presence of sources close to the location of…
We check how the Fermi/LAT data constrain physics of hot accretion flows, most likely present in low-luminosity AGNs. Using a precise model of emission from hot flows, we examine the dependence of their gamma-ray emission, resulting from…
Context: Composite galaxies that contain both Seyfert and starburst components may produce very high-energy (VHE; >100 GeV) gamma-ray emission at a wide range of spatial scales, from a few Schwarzschild radii of a supermassive black hole to…
The recent detection of high-energy neutrinos by IceCube in the direction of the nearby Seyfert/starburst galaxy NGC 1068 implies that radio-quiet active galactic nuclei can accelerate cosmic-ray ions. Dedicated multi-messenger analyses…
The $\gamma$-ray loud narrow line Seyfert 1 ($\gamma$-NLSy1) galaxy PKS 1502+036 ($z=0.409$) exhibited its first $\gamma$-ray outburst on 2015 December 20. In the energy range of 0.1-300 GeV, the highest flux measured by {\it Fermi}-Large…
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…
We report the discovery of gamma-ray emission from two radio-loud narrow-line Seyfert 1 galaxies using data from Fermi/LAT: J0804+3853 (z = 0.211) and J1443+4725 (z = 0.502). The objects were discovered due to singular, separate, and brief…
The nuclear activity typical of Seyfert galaxies can drive powerful winds where high-energy phenomena occur. In spite of their high power content, the number of such non-jetted active galactic nuclei (AGN) detected in gamma rays is very…
We present the analysis of 2.1 years of Fermi/LAT data on 491 Seyfert galaxies detected by the Swift/BAT survey. Only the two nearest objects, NGC 1068 and NGC 4945, which were identified in the Fermi First-year Catalog, are detected. Using…
We present optical spectra for new infrared Seyfert galaxies obtained with the 2.16m telescope at Beijing Astronomical Observatory (BAO). After wavelength and flux calibration, they are classified by the degree of nuclear activity: nine…
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…
Recent observations of high-energy neutrinos by IceCube and gamma rays by the Fermi Large Area Telescope (LAT) and the MAGIC telescope have suggested that neutrinos are produced in gamma-ray opaque environments in the vicinity of…
Recent studies have found a positive correlation between the star-formation rate of galaxies and their gamma-ray luminosity. Galaxies with a high star-formation rate are expected to produce a large amount of high-energy cosmic rays, which…
NGC 1068 is a nearby widely studied Seyfert II galaxy presenting radio, infrared, X- and $\gamma$-ray emission as well as strong evidence for high-energy neutrino emission. Recently, the evidence for neutrino emission could be explained in…
Galaxy clusters could produce gamma-rays from inverse Compton scattering of cosmic ray electrons or hadronic interactions of cosmic ray protons with the intracluster medium. It is still an open question on whether gamma-ray emission ($>$…
During the past few years, first observations of starburst galaxies at >GeV energies could be made with the Fermi Gamma-ray Space Telescope (GeV range) and Imaging Air Cherenkov Telescopes (TeV range). The two nearest starbursts, M82 and…
With the discovery of high energy {\gamma}-ray emission from the Andromeda galaxy (M 31) by the Fermi/LAT collaboration, normal galaxies begin to arise from the shadows for the first time, providing insight on cosmic ray acceleration in…
Star-forming and starburst galaxies (SFGs and SBGs) are powerful emitters of non-thermal $\gamma$-rays and neutrinos, due to their intense phases of star-formation activity, which should confine high-energy Cosmic-Rays (CRs) inside their…
We report the discovery by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope of high-energy gamma-ray emission from the peculiar quasar PMN J0948+0022 (z=0.585+/-0.001). Contrary to the expectations, the optical…
Radio-quiet Seyfert galaxies have been detected in GeV gamma-rays by the $Fermi$ Large Area Telescope (LAT), but the origin of much of this emission is unclear. We consider the nearby example, the Seyfert galaxy GRS 1734-292, which exhibits…