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The typical optical-UV continuum slopes observed in many type 1 AGN are redder than expected from thin accretion disk models. A possible resolution to this conundrum is that many AGN are reddened by dust along the line of sight. To explore…

Astrophysics of Galaxies · Physics 2016-11-15 Dalya Baron , Jonathan Stern , Dovi Poznanski , Hagai Netzer

The unified model of active galactic nuclei (AGN) claims that the properties of AGN depend on the viewing angle of the observer with respect to a toroidal distribution of dust surrounding the nucleus. Both the mid-infrared (MIR) attenuation…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 O. Gonzalez-Martin , J. M. Rodriguez-Espinosa , T. Diaz-Santos , C. Packham , A. Alonso-Herrero , P. Esquej , C. Ramos Almeida , R. Mason , C. Telesco

Dust-obscured galaxies (DOGs) with extreme infrared luminosities may represent a key phase in the co-evolution of galaxies and supermassive black holes. We select 12 DOGs at $0.3\lesssim z\lesssim1.0$ with broad Mg II or H$\beta$ emission…

Astrophysics of Galaxies · Physics 2020-09-30 Fan Zou , William N. Brandt , Fabio Vito , Chien-Ting Chen , Gordon P. Garmire , Daniel Stern , Ashraf Ayubinia

For a compiled sample of 120 reverberation-mapped AGNs, the bivariate correlations of the broad-line regions (BLRs) size ($R_{\rm BLR}$) with the continuum luminosity at 5100 \AA\ ($L_{5100}$) and the dimensionless accretion rates…

Astrophysics of Galaxies · Physics 2020-01-08 Li-Ming Yu , Bi-Xuan Zhao , Wei-Hao Bian , Chan Wang , Xue Ge

The dusty torus plays a vital role in unifying active galactic nuclei (AGNs). However, the physical structure of the torus remains largely unclear. Here we present a systematical investigation of the torus mid-infrared (MIR) spectroscopic…

High Energy Astrophysical Phenomena · Physics 2020-09-30 Jun Xu , Mouyuan Sun , Yongquan Xue , Junyao Li , Zhicheng He

Observations give strong support for the unification scheme of active galactic nuclei. Clumpiness of the toroidal obscuration is crucial for explaining the IR observations and has significance consequences for AGN classification: type 1 and…

Astrophysics · Physics 2007-05-23 Moshe Elitzur

The inner structure of AGNs is expected to change below a certain luminosity limit. The big blue bump, footprint of the accretion disk, is absent for the majority of low-luminosity AGNs (LLAGNs). Moreover, recent simulations suggest that…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 J. A. Fernández-Ontiveros , M. A. Prieto , J. A. Acosta-Pulido , M. Montes

Several recent studies have reported different intrinsic correlations between the AGN mid-IR luminosity ($L_{MIR}$) and the rest-frame 2-10 keV luminosity ($L_{X}$) for luminous quasars. To understand the origin of the difference in the…

We present the main results from a long-term reverberation mapping campaign carried out for the Seoul National University Active Galactic Nuclei (AGN) Monitoring Project. High-quality data were obtained during 2015-2021 for 32 luminous AGNs…

Information on the structure around active galactic nuclei (AGN) has long been derived from measuring lags in their varying light output at different wavelengths. In principle, infrared data would reach to larger radii, potentially even…

Astrophysics of Galaxies · Physics 2021-03-17 E. Elmer , M. Merrifield , O. Almaini , W. G. Hartley , D. T. Maltby

We study the relative dust attenuation-inclination relation in 78,721 nearby galaxies using the axis ratio dependence of optical-NIR colour, as measured by the Sloan Digital Sky Survey (SDSS), the Two Micron All Sky Survey (2MASS), and the…

Astrophysics of Galaxies · Physics 2017-03-23 Brian Devour , Eric Bell

The Fe Kalpha emission line is the most ubiquitous feature in the X-ray spectra of active galactic nuclei (AGN), but the origin of its narrow core remains uncertain. Here, we investigate the connection between the sizes of the Fe core…

High Energy Astrophysical Phenomena · Physics 2015-10-21 Poshak Gandhi , Sebastian F. Hoenig , Makoto Kishimoto

A 7.5 years spectrophotometric monitoring program of 28 Palomar-Green quasars to determine the size of their broad emission line region (BLR) is reviewed. We find both the continuum and the emission line fluxes of all quasars to vary during…

Astrophysics · Physics 2007-05-23 Shai Kaspi

We analyze JWST NIRSpec$+$MIRI/MRS observations of the infrared (IR) gas-phase molecular bands of the most enshrouded source (D1) within the interacting system and luminous IR galaxy II Zw 096. We report the detection of rovibrational lines…

We have combined the CLASXS Chandra survey in Lockman with the Spitzer SWIRE survey data to study the X-ray-infrared connection for AGN. The sample consists of 401 X-ray-sources, of which 306 are detected by Spitzer, and a further 257 AGN…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-02 Michael Rowan-Robinson , Ivan Valtchanov , Kirpal Nandra

Recent observations of NGC 1068 and other AGN support the idea of a geometrically and optically thick dust torus surrounding the central supermassive black hole and accretion disk of AGN. In type 2 AGN, the torus is seen roughly edge-on,…

Astrophysics · Physics 2007-05-23 S. F. Hoenig , T. Beckert , K. Ohnaka , G. Weigelt

Unified schemes of active galactic nuclei (AGN) require an obscuring dusty torus around the central engine. Torus sizes of hundreds of parsecs were deduced from early theoretical modeling efforts, but high-resolution IR observations now…

Astrophysics · Physics 2007-05-23 Moshe Elitzur

Mid-infrared spectroscopic measurements from the Infrared Spectrometer on Spitzer (IRS) are given for 125 hard X-ray AGN (14-195 keV) from the Swift Burst Alert Telescope sample and for 32 AGN with black hole masses from reverberation…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Daniel Weedman , Lusine Sargsyan , Vianney Lebouteiller , James Houck , Donald Barry

We report the clearest detection to date of dusty torus signatures in a Weak-Line Radio Galaxy (WLRG). The deep Spitzer InfraRed Spectrograph (IRS) rest-frame mid-infrared (MIR) spectrum of the WLRG PKS 0043-42 (z=0.116) shows a clear…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Cristina Ramos Almeida , Daniel Dicken , Clive Tadhunter , A. Asensio Ramos , K. J. Inskip , M. J. Hardcastle , B. Mingo