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Broad emission lines in active galactic nuclei (AGNs) mainly arise from gas photoionized by continuum radiation from an accretion disk around a central black hole. The shape of the broad-line profile, described by ${\cal D}_{_{\rm…

Astrophysics of Galaxies · Physics 2016-02-17 Pu Du , Jian-Min Wang , Chen Hu , Luis C. Ho , Yan-Rong Li , Jin-Ming Bai

We report the discovery of an Active Galactic Nucleus (AGN) in the nearby SAd galaxy NGC 3621 using Spitzer high spectral resolution observations. These observations reveal the presence of [NeV] 14 um and 24 um emission which is centrally…

Astrophysics · Physics 2019-08-19 S. Satyapal , D. Vega , T. Heckman , B. O'Halloran , R. Dudik

The main fuelling processes for Active Galactic Nuclei (AGN) are currently unknown. Previous work showed that galaxies with a large kinematic misalignment between their stellar and gas reservoirs have a higher AGN fraction than galaxies…

Outflows in active galactic nuclei (AGNs) are crucial to understand in investigating the co-evolution of supermassive black holes (SMBHs) and their host galaxies since outflows may play an important role as an AGN feedback mechanism. Based…

Astrophysics of Galaxies · Physics 2019-01-04 Jaejin Shin , Tohru Nagao , Jong-Hak Woo

We present a comprehensive spectroscopic and variability-based characterisation of a sample of low-luminosity active galactic nuclei (AGNs) hosting low mass black holes, identified by $H\beta$ full width at half maximum (FWHM) $< 2200$ km…

Astrophysics of Galaxies · Physics 2025-12-09 Himanshu Sharma , Vivek Kumar Jha , Hum Chand , Swayamtrupta Panda

Growing supermassive black holes (Active Galactic Nuclei; AGN) release energy with the potential to alter their host galaxies and larger-scale environment; a process named "AGN feedback". Feedback is a required component of galaxy formation…

Astrophysics of Galaxies · Physics 2024-04-15 Chris M. Harrison , Cristina Ramos Almeida

We present a study of variability time scales in a large sample of Active Galactic Nuclei at several frequencies between 4.8 and 230 GHz. We investigate the differences of various AGN types and frequencies and correlate the measured time…

The absence of intrinsic broad line emission has been reported in a number of active galactic nuclei (AGN), including some with high Eddington ratios. Such "true type 2 AGN" are inherent to the disk-wind scenario for the broad line region:…

Astrophysics of Galaxies · Physics 2016-04-27 Moshe Elitzur , Hagai Netzer

Active Galactic Nuclei (AGN) have long been known to be variable, but the amplitude, timescale and nature of these changes can often differ dramatically from object to object. The richest source of information about the properties of AGN…

Astrophysics of Galaxies · Physics 2021-07-14 Hartmut Winkler

The unified model of active galactic nuclei (AGN) includes a toroidal obscuring structure to explain the differences between Type I and Type II AGN as an effect of inclination angle. This toroidal structure is thought to be 'clumpy' as the…

Astrophysics of Galaxies · Physics 2023-01-19 Isaiah Cox , Nuria Torres-Alba , Stefano Marchesi , Xiurui Zhao , Marco Ajello , Andrealuna Pizzetti , Ross Silver

In order to relate the observed evolution of the galaxy stellar mass function and the luminosity function of active galactic nuclei (AGN), we explore a co-evolution scenario in which AGN are associated only with the very last phases of the…

Astrophysics of Galaxies · Physics 2018-11-28 Neven Caplar , Simon J. Lilly , Benny Trakhtenbrot

Active Galactic Nuclei (AGN) represent the growth phases of the supermassive black holes in the center of almost every galaxy. Powerful, highly ionized winds, with velocities $\sim 0.1- 0.2c$ are a common feature in X--ray spectra of…

Astrophysics of Galaxies · Physics 2015-09-23 Andrew King , Ken Pounds

Active Galactic Nuclei (AGNs) are characterized by strong temporal flux density variability across the electromagnetic spectrum, offering insights into the complex physical processes governing accretion and plasma outflows. To…

Astrophysics of Galaxies · Physics 2026-02-25 Lang Cui , Krishna Mohana A , Xin Wang , Ning Chang , Guiping Tan , Xiang Liu

We analyze four extreme active galactic nuclei (AGN) transients to explore the possibility that they are caused by rare, high-amplitude microlensing events. These previously unknown type-I AGN are located in the redshift range 0.6-1.1 and…

Here we investigate the connection of broad emission line shapes and continuum light curve variability time scales of type-1 Active Galactic Nuclei (AGN). We developed a new model to describe optical broad emission lines as an accretion…

Astrophysics of Galaxies · Physics 2018-05-21 E. Bon , P. Jovanovic , P. Marziani , N. Bon , A. Otasevic

We examine the connection between galaxy mergers and the triggering of active galactic nuclei (AGNs) using a sample of 614 type 1 AGNs at $z<0.07$, along with a control sample of inactive galaxies matched to the AGNs for comparison. We used…

Astrophysics of Galaxies · Physics 2025-12-03 Yongmin Yoon , Yongjung Kim , Dohyeong Kim , Kyungwon Chun , Woowon Byun

A key feature of active galactic nuclei (AGN) is their variability across all wavelengths. Typically, AGN vary by a few tenths of a magnitude or more over periods lasting from hours to years. By contrast, extreme variability of AGN -- large…

High Energy Astrophysical Phenomena · Physics 2024-03-12 Summer A. J. McLaughlin , James R. Mullaney , Stuart P. Littlefair

We construct the rest-frame 2--10 keV intrinsic X-ray luminosity function of Active Galactic Nuclei (AGNs) from a combination of X-ray surveys from the all-sky Swift BAT survey to the Chandra Deep Field-South. We use ~3200 AGNs in our…

Differentiating between active galactic nuclei (AGN) activity and star formation in z ~ 2 galaxies is difficult because traditional methods, such as line ratio diagnostics, change with redshift while multi-wavelength methods (X-ray, radio,…

We compiled a sample of 73 active galactic nuclei (AGNs) with reverberation mapping (RM) observations from RM campaigns including our ongoing campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs). This sample covers…