相关论文: Active Galactic Nuclei: Unification, Blazar Variab…
The appearance of active galactic nuclei (AGN) depends so strongly on orientation that our current classification schemes are dominated by random pointing directions instead of more interesting physical properties. Light from the centers of…
The radio-loud AGN unification model associates powerful radio galaxies with radio-loud quasars and blazars. In analogy with the radio-quiet scheme, the nuclear regions of objects showing only narrow emission lines in their optical spectrum…
We present deep Near-infrared (NIR) images of a sample of 19 intermediate-redshift ($0.3<z<1.0$) radio-loud active galactic nuclei (AGN) with powerful relativistic jets ($L_{1.4GHz} >10^{27}$ WHz$^{-1}$), previously classified as…
The spectra of Active Galactic Nuclei (AGNs) are often characterized by a wealth of emission lines with different profiles and intensity ratios that led to a complicated classification. Their electro-magnetic radiation spans more than 10…
Active Galactic Nuclei (AGN) are highly energetic astrophysical sources powered by accretion onto supermassive black holes in galaxies, which present unique observational signatures covering the full electromagnetic spectrum (and more) over…
Combined investigations of the clustering properties of galaxies of different spectral type and high-redshift quasars strongly suggest local ellipticals to be the parent population of optically bright Active Galactic Nuclei (AGN). However,…
In this third of a series of papers concerning active galaxies in the FIRST and Sloan Digital Sky Surveys, we analyze the spectroscopic and radio properties of a sample of narrow-line Active Galactic Nuclei (AGN), broad-line Seyfert I…
The recent development of unified theories of active galactic nuclei (AGN) has indicated that there are two physically distinct classes of these objects - radio-loud and radio-quiet. The primary observational distinctions between the two…
Active Galactic Nuclei (AGN) are now known to be strong gamma-ray emitters. After briefly describing the different classes of AGN and the basic tenets of unified schemes, I discuss the role of blazars (that is BL Lacs and flat-spectrum…
This article focuses on certain variability and emission characteristics of Active Galactic Nuclei (AGN), especially their radio-loud subset consisting of quasars, BL Lacs and $\gamma$-ray detected narrow-line Seyfert 1 galaxies, all of…
Active Galactic Nuclei (AGN) are now known to be strong gamma-ray emitters. After briefly describing AGN classification and the main ideas behind unified schemes, I summarize the main properties of blazars (that is BL Lacs and flat-spectrum…
Associated with one of the most important forms of active galactic nucleus (AGN) feedback, and showing a strong preference for giant elliptical host galaxies, radio AGN (L_1.4GHz > 10^24 W Hz^-1) are a key sub-class of the overall AGN…
Radio and gamma-ray emission from active galactic nuclei (AGN) are thought to share a common origin, related to the ejection phenomena in the vicinity of supermassive black holes. Thanks to its sensitivity, surveying capability, and broad…
Analysis of the frequency and physical properties of galaxies with star-formation and AGN activity in different environments in the local universe is a cornerstone for understanding structure formation and galaxy evolution. We have built a…
Representing simultaneous black hole accretion during a merger, binary active galactic nuclei (AGNs) could provide valuable observational constraints to models of galaxy mergers and AGN triggering. High-resolution radio interferometer…
We compute the cross-correlation between a sample of 14,000 radio-loud AGN (RLAGN) with redshifts between 0.4 and 0.8 selected from the Sloan Digital Sky Survey and a reference sample of 1.2 million luminous red galaxies in the same…
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)…
Historically, Seyfert nuclei have been considered to be radio-quiet active galactic nuclei (AGNs). We question this widely held assumption by showing that the distribution of the radio-to-optical luminosity ratio R, when properly measured…
After briefly summarizing the main tenets of unified schemes of Active Galactic Nuclei, I review some recent results in the field of unification of radio-loud sources, both for the low-luminosity (BL Lacs and Fanaroff-Riley type I radio…
Active Galactic Nuclei (AGN) are remarkable astronomical sources emitting over the whole electromagnetic spectrum, with different bands providing unique windows on distinct sub-structures and their related physics. AGN come in a large…