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We study the broad-band spectral energy distribution (SED) of the prototypical low-mass active galactic nucleus (AGN) in NGC 4395. We jointly model the optical through mid-infrared SED with a combination of galaxy and AGN light, and find…

Astrophysics of Galaxies · Physics 2023-07-31 Hector Afonso G. Cruz , Andy D. Goulding , Jenny E. Greene

We studied AGN activity in twelve LSSs in the ORELSE survey, at 0.65<z<1.28, using a combination of Chandra observations, optical and NIR imaging and spectroscopy. We located a total of 61 AGNs across our sample that were successfully…

Astrophysics of Galaxies · Physics 2017-01-18 N. Rumbaugh , B. Lemaux , A. Tomczak , D. Kocevski , L. Lubin , P. -F. Wu , R. Gal , L. Shen , A. Mansheim , C. Fassnacht , G. Squires

A complete census of Active Galactic Nuclei (AGN) is a prerequisite for understanding the growth of supermassive black holes across cosmic time. A significant challenge toward this goal is the whereabouts of heavily obscured AGN that remain…

Most active supermassive black holes (SMBH) in present-day galaxies are underfed and consist of low-luminosity active galactic nuclei (LLAGN). They have multiwavelength broadband spectral energy distributions (SED) dominated by non-thermal…

Astrophysics of Galaxies · Physics 2021-02-12 Ivan Almeida , Roberta Duarte , Rodrigo Nemmen

Emission from active galactic nuclei (AGNs) is known to play an important role in the evolution of many galaxies including luminous and ultraluminous systems (U/LIRGs), as well as merging systems. However, the extent, duration, and exact…

More than one third of all nearby galaxies show indications of low-luminosity nuclear activity. These low-luminosity AGNs (LLAGNs) are traditionally classified into a variety of categories depending on their forbidden-line ratios and on the…

Astrophysics · Physics 2007-05-23 A. J. Barth

This paper reviews our current understanding of low-luminosity AGNs (LLAGNs) in the context of the advection-dominated accretion flow. The best investigated source, the supermassive black hole in our galactic center, Sgr A*, is emphasized…

Astrophysics · Physics 2007-05-23 Feng Yuan

We explored a sample of 545 local galaxies using data from the 3XMM-DR7 and SDSS-DR8 surveys. We carried out all analyses up to z\,$\sim$\,0.2, and we studied the relation between X/O flux ratio and accretion rate for different classes of…

Astrophysics of Galaxies · Physics 2021-07-14 Asrate Gaulle , Mirjana Pović , Dejene Zewdie

Over the last few years X-ray observations of broad-line radio galaxies (BLRGs) by ASCA, RXTE and BeppoSAX have shown that these objects seem to exhibit weaker X-ray reflection features (such as the iron K\alpha line) than radio-quiet…

Astrophysics · Physics 2009-11-07 D. R. Ballantyne , R. R. Ross , A. C. Fabian

According to the standard paradigm, the strong and compact luminosity of active galactic nuclei (AGN) is due to multi-temperature black body emission originating from an accretion disk formed around a supermassive black hole. This central…

Astrophysics of Galaxies · Physics 2016-10-18 P. Andrea Rojas Lobos , Rene W. Goosmann , Frederic Marin

We report Swift observations of a sample of 92 bright soft X-ray selected active galactic nuclei (AGN). This sample represents the largest number of AGN observed to study the spectral energy distribution (SED) of AGN with simultaneous…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Dirk Grupe , S. Komossa , Karen M. Leighly , Kim L. Page

We present a comprehensive study of accretion activity in the most underdense environments in the universe, the voids, based on the SDSS DR2 data. Based on investigations of multiple void regions, we show that AGN's occurrence rate and…

Astrophysics · Physics 2009-11-13 Anca Constantin , Fiona Hoyle , Michael S. Vogeley

Active Galactic Nuclei (AGNs) are characterized by emission of radiation over more than 10 orders of magnitude in frequency. Therefore, the execution of extensive surveys of the sky, with different types of detectors, is providing the…

The discovery of changing-look active galactic nuclei (CLAGNs) with the significant change of optical broad emission lines (optical CLAGNs) and/or strong variation of line-of-sight column densities (X-ray CLAGNs) challenges the…

High Energy Astrophysical Phenomena · Physics 2022-03-30 Lyu Bing , Wu Qingwen , Yan Zhen , Yu Wenfei , Liu Hao

We present X-ray spectral variability of 24 local active galactic nuclei (AGN) from the Palomar sample of nearby galaxies, as observed mainly by Swift. From hardness ratio measurements, we find that 18 AGN with low accretion rates show…

High Energy Astrophysical Phenomena · Physics 2016-04-27 S. D. Connolly , I. M. McHardy , C. J. Skipper , D. Emmanoulopoulos

Understanding the relationship between galaxies hosting active galactic nuclei (AGN) and the dark matter halos in which they reside is key to constraining how black-hole fueling is triggered and regulated. Previous efforts have relied on…

Astrophysics of Galaxies · Physics 2015-06-23 A. Leauthaud , A. J. Benson , F. Civano , A. L. Coil , K. Bundy , R. Massey , M. Schramm , A. Schulze , P. Capak , M. Elvis , A. Kulier , J. Rhodes

Quasar accretion disks are believed to form stars by self-gravity. Low Luminosity Active Galactic Nuclei (LLAGN) are much dimmer galactic centers, and are often believed to be quasars that ran out of gaseous fuel. LLAGN accretion disks…

Astrophysics · Physics 2009-11-10 Sergei Nayakshin

To study the impact of active galactic nuclei (AGN) feedback on the galactic ISM, we present Magellan long-slit spectroscopy of 12 luminous nearby type 2 AGN (L_bol~10^{45.0-46.5} erg/s, z~0.1). These objects are selected from a parent…

Astrophysics of Galaxies · Physics 2017-02-08 Ai-Lei Sun , Jenny E. Greene , Nadia L. Zakamska

The physical origin of optical changing-look AGNs (CLAGNs), characterized by the appearance or disappearance of broad emission lines, is thought to be mainly driven by the variation of the black-hole (BH) accretion rate. In this work, we…

High Energy Astrophysical Phenomena · Physics 2026-04-15 Pengyuan Han , Huaiyuan Lu , Bing Lyu , Jiancheng Wu , Qingwen Wu

We put active galactic nuclei (AGNs) with low-mass black holes on the fundamental plane of black hole accretion---the plane that relates X-ray emission, radio emission, and mass of an accreting black hole---to test whether or not the…

High Energy Astrophysical Phenomena · Physics 2015-07-22 Kayhan Gultekin , Edward M. Cackett , Ashley L. King , Jon M. Miller , Jason Pinkney