Related papers: On the two main classes of Active Galactic Nuclei
Establishing the role of active galactic nuclei (AGN) during the formation of galaxies remains one of the greatest challenges of galaxy formation theory. Towards addressing this, we summarise our recent work investigating: (1) the physical…
We report on a new method to identify Active Galactic Nuclei (AGN) among unidentified INTEGRAL sources. This method consists of cross-correlating unidentified sources listed in the fourth IBIS Survey Catalogue first with infrared and then…
The evolution of extragalactic radio sources has been a fundamental problem in the study of active galactic nuclei for many years. A standard evolutionary model has been created based on observations of a wide range of radio sources. In the…
A thorough study of radio emission in Active Galactic Nuclei (AGN) is of fundamental importance to understand the physical mechanisms responsible for the emission and the interplay between accretion and ejection processes. High frequency…
Radio-loud sources with blazar-like properties, but having a jet that does not directly point in the direction of the observer are among the most interesting classes of gamma-ray emitters. These sources are known as Misaligned Active…
The dichotomy between radio-loud (RL) and radio-quiet (RQ) active galactic nuclei (AGN) is thought to be intrinsically related to radio jet production. This difference may be explained by the presence of a strong magnetic field (B-field)…
We present results of recurrence analysis of 46 active galactic nuclei (AGN) using light curves from the 157-month catalog of the Swift Burst Alert Telescope (BAT) in the 14-150 keV band. We generate recurrence plots and compute recurrence…
Mature radio galaxies such as M87 belong to a specific subclass of active galaxies (AGN) whose evolution in time endows them with five distinguishing characteristics, including (1) low excitation emission, (2) low star formation rates, (3)…
Various radio galaxies show signs of having gone through episodic jet outbursts in the past. An example is the class of double-double radio galaxies (DDRGs). However, to follow the evolution of an individual source in real-time is…
The central nuclei of galaxies, where super-massive black holes (SMBHs) are thought to reside, can experience phases of activity when they become Active Galactic Nuclei (AGN). An AGN can eject winds, jets, and produce radiation across the…
Active Galactic Nuclei can be copious extragalactic emitters of MeV-GeV-TeV gamma rays, a phenomenon linked to the presence of relativistic jets powered by a super-massive black hole in the center of the host galaxy. Most of gamma-ray…
The inevitable spread in properties of the toroidal obscuration of active galactic nuclei (AGNs) invalidates the widespread notion that type 1 and 2 AGNs are intrinsically the same objects, drawn randomly from the distribution of torus…
Active Galactic Nuclei (AGN) are sources of high-energy gamma-rays and are considered to be promising candidates to be sources of high-energy cosmic rays and neutrinos as well. We present and discuss various models for ion acceleration and…
Presently there are several classes of detected gamma-ray extragalatic sources. They are mostly associated to active galactic nuclei (AGN) and (at soft gamma rays) to gamma-ray bursts (GRB), but not only. Active galactic nuclei consist of…
The discovery in 2008 of high-energy gamma-rays from Narrow-Line Seyfert 1 Galaxies (NLS1s) made it clear that there were active galactic nuclei (AGN) other than blazars and radio galaxies that can eject powerful relativistic jets. In…
We present optical longslit observations of the complete sample of 71 Type 2 active galactic nuclei (AGNs) with double-peaked narrow emission lines at $z < 0.1$ in the Sloan Digital Sky Survey. Double-peaked emission lines are produced by a…
Physical processes such as re-ignition, enhancement, and fading of active galactic nuclei (AGN) are not entirely understood because the timeline of these events is expected to last many years. However, it is well known that the differences…
It is now established that the faint radio population is a mixture of star-forming galaxies and faint active galactic nuclei (AGNs), with the former dominating below S(1.4GHz) \sim 100 muJy and the latter at larger flux densities. The faint…
Context. Active galactic nuclei (AGNs) and star forming galaxies (SFGs) are the primary sources of extragalactic radio sky. But it is difficult to distinguish the radio emission produced by AGNs from that by SFGs, especially when the radio…
We review the continuum emission of Active Galactic Nuclei (AGN) over the entire electromagnetic spectrum. After a brief historical introduction, we describe the main spectral properties of unobscured AGN, discussing the selection biases…