Related papers: Magnetospheric Gamma-Ray Emission in Active Galact…
Binary black holes (BBHs) in the vicinity of Active Galactic Nuclei (AGNs) are particularly interesting systems from both a cosmological and astrophysical point of view. Matter and radiation fields within the dense AGN environment could…
We study the observed relation between accretion rate (in terms of L/L_Edd) and shape of the hard X-ray spectral energy distribution (namely the photon index Gamma_X) for a large sample of 228 hard X-ray selected, low-redshift active…
Radiation emitted from an accretion disk around a massive black hole is a widely discussed model for the UV/soft X-ray excess emission observed in the spectra of many AGN. A self-consistent calculation of the structure and the emerging…
The emission of very-high-energy photons (VHE, E$>$100 GeV) in active galactic nuclei (AGN) is closely connected with the production of ultra-relativistic particles. Among AGN, the subclass of extreme BL Lacertae are of particular interest…
Gamma-ray emission in active galaxies is likely produced within the inner jet, or in the close vicinity of the supermassive black hole (SMBH) at sub-parsec distances. Gamma rays have to pass through the surrounding massive stellar cluster…
M87 is one of the closest (z=0.00436) extragalactic sources emitting at very-high-energies (VHE, E > 100 GeV). The aim of this work is to locate the region of the VHE gamma-ray emission and to describe the observed broadband spectral energy…
We present an analysis of the X-ray spectrum and long-term variability of the nearby dwarf starburst galaxy Henize 2-10. Recent observations suggest that this galaxy hosts an actively accreting black hole with mass ~10^6 M_sun. The presence…
This is the second in a series of papers aiming to test how the mass ($M_{\rm BH}$), accretion rate ($\dot{M}$) and spin ($a_{*}$) of super massive black holes (SMBHs) determine the observed properties of type-I active galactic nuclei…
We investigate the electrostatic acceleration of electrons and positrons in the vicinity of the event horizon, applying the pulsar outer-gap model to black hole magnetospheres. During a low accretion phase, the radiatively inefficient…
Active galactic nuclei present continuum and line emission. The emission lines are originated by gas located close to the central super-massive black hole. Some of these lines are broad, and would be produced in a small region called…
GH 10 is a broad-lined active galactic nucleus (AGN) energized by a black hole of mass 800,000 Solar masses. It was the only object detected by Greene et al. in their Very Large Array (VLA) survey of 19 low-mass AGNs discovered by Greene &…
Context. Ultra fast outflows (UFOs) from active galactic nuclei (AGN) are expected to lead to the formation of sub-relativistic strong shocks expanding in a dense circumnuclear medium, and thus have the potential for being efficient…
The production of very-high-energy (VHE, $E_{\gamma} \gtrsim 100$ GeV) gamma rays resulting from the scattering of high-energy cosmic-ray protons off axion-like particles (ALPs) populating the dark matter halo of the Milky Way is…
Recent astronomical observations reveal that Active Galactic Nuclei (AGN) are sources of high-energy radiation. For example, the Fermi-LAT and Hess telescopes have detected gamma-ray emissions from the cores of several types of AGN's. Even…
We present a systematic investigation of extremely X-ray variable active galactic nuclei (AGNs) in the $\approx 5.3~{\rm deg}^2$ XMM-SERVS XMM-LSS region. Eight variable AGNs are identified with rest-frame 2 keV flux density variability…
Understanding the relative roles of large-scale environment and internal host-galaxy processes in shaping AGN activity is essential for constraining models of black-hole growth and galaxy evolution. We investigate how the environment of…
We conducted an analysis of gamma-ray variability in a large sample of jetted active galactic nuclei (AGNs) by utilizing archival Fermi-LAT light curves and applying damped random walk modeling to obtain variability amplitude. Our primary…
The origin of outflow in narrow-line region (NLR) of active galactic nucleus (AGN) is studied in this paper by focusing on the relationship between the [\ion{O}{3}]$\lambda$5007 line profile and the hard X-ray (in a bandpass of 2-10 keV)…
For nearly seven decades astronomers have been studying active galaxies, that is to say galaxies with actively accreting central supermassive black holes, AGN. A small fraction of these are characterized by luminous, powerful radio…
For most of their lifetime, super-massive black holes (SMBHs) commonly found in galactic nuclei obtain mass from the ambient at a rate well below the Eddington limit, which is mediated by a radiatively inefficient, hot accretion flow. Both…