Related papers: Active Galactic Nuclei and their demography throug…
Active Galactic Nuclei (AGNs) are among the most luminous objects in the universe, making them valuable probes for studying galaxy evolution. However, understanding how AGN properties evolve over cosmic time remains a fundamental challenge.…
Powerful radio galaxies at high redshift are highly useful in studies of early evolution of AGN-hosting galaxies because their observed optical and near infrared light are dominated by their stellar population rather than the nonthermal…
High resolution X-ray spectroscopy of the hot gas in galaxy clusters has shown that the gas is not cooling to low temperatures at the predicted rates of hundreds to thousands of solar masses per year. X-ray images have revealed giant…
Deep field observations are an essential tool to probe the cosmological evolution of galaxies. In this context, X-ray deep fields provide information about some of the most energetic cosmological objects: active galactic nuclei (AGN).…
Non-blazar Active Galactic Nuclei (AGN) have emerged as a new gamma-ray emitting source class on the extragalactic sky and started to deepen our understanding of the physical processes and the nature of AGN in general. The detection of…
Adopting the hypothesis that the nonthermal emission of Active Galactic Nuclei (AGN) is primarily due to the acceleration of protons, we construct a simple model in which the interplay of acceleration and losses can be studied together with…
Context: Variations in the mass accretion rate appear to be responsible for the rapid transitions in spectral type that are observed in increasingly more active galactic nuclei (AGNs). These objects are now labeled "changing-look" AGNs and…
The Unified Model of Active Galactic Nuclei (UMAGN) is a comprehensive theoretical framework aimed at elucidating the diverse observations of AGN, encompassing quasars and Seyfert galaxies. The Model attributes the observed variations to…
Recent models of super-massive black hole (SMBH) and host galaxy joint evolution predict the presence of a key phase where accretion, traced by obscured Active Galactic Nuclei (AGN) emission, is coupled with powerful star formation. Then…
We examine the possibility of the active galactic nucleus (AGN) obscuration by dusty gas clouds that spurt out from circumnuclear starburst regions. For the purpose, the dynamical evolution of gas clouds is pursued, including the effects of…
The central engines of Active Galactic Nuclei (AGNs) are powered by accreting supermassive black holes, and while AGNs are known to play an important role in galaxy evolution, the key physical processes occur on scales that are too small to…
We study the effect of active galactic nuclei (AGN) heating on the chemodynamical evolution of elliptical galaxies and their X-ray and optical properties using high-resolution Lambda-dominated cold dark matter cosmological simulations. Our…
Active galactic nuclei (AGN) show evidence for reprocessing gas, outflowing from the accreting black hole. The combined effects of absorption and scattering from the circumnuclear material likely explains the `hard excess' of X-ray emission…
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…
Supermassive black holes (SMBHs) have been found to be ubiquitous in the nuclei of early-type galaxies and of bulges of spirals. There are evidences of a tight correlation between the SMBH masses, the velocity dispersions of stars in the…
There has been a growing body of evidence to suggest that AGN activity, which is powered by mass accretion on to a supermasive black hole, could be episodic, although the range of time scales involved needs to be explored further. The…
We summarize what large surveys of the contemporary universe have taught us about the physics and phenomenology of the processes that link the formation and evolution of galaxies and their central supermassive black holes. We present a…
This paper summarizes the observations which provide the best evidence for the presence of black holes in active galactic nuclei. This includes: X-ray variability; kinematical studies using optical emission lines as well as the distribution…
Astronomers knew early in the twentieth century that some galaxies have emission-line nuclei. However, even the systematic study by Seyfert (1943) was not enough to launch active galactic nuclei (AGN) as a major topic of astronomy. The…
Active Galactic Nuclei (AGN) are traditionally divided empirically into two main classes: "radio-loud" and "radio-quiet" sources. These labels, which are more than fifty years old, are obsolete, misleading, and wrong. I argue that AGN…