scholarly journals Nuclear/Circumnuclear Starbursts and Active Galactic Nucleus Mass Accretion in Seyfert Galaxies

2008 ◽  
Vol 677 (2) ◽  
pp. 895-905 ◽  
Author(s):  
Yasuyuki Watabe ◽  
Nozomu Kawakatu ◽  
Masatoshi Imanishi
Keyword(s):  
Active Galactic Nucleus ◽  
Seyfert Galaxies ◽  
Nucleus Mass

scholarly journals Research Note On the relation between the IR continuum and the active galactic nucleus in Seyfert galaxies

2001 ◽  
Vol 377 (1) ◽  
pp. 60-65 ◽  
Author(s):  
M. A. Prieto ◽  
A. M. Pérez García ◽  
J. M. Rodríguez Espinosa
Keyword(s):  
Active Galactic Nucleus ◽  
Seyfert Galaxies ◽  
Research Note

scholarly journals Probing the active galactic nucleus unified model torus properties in Seyfert galaxies

2016 ◽  
Vol 464 (2) ◽  
pp. 2139-2173 ◽  
Author(s):  
Anelise Audibert ◽  
Rogério Riffel ◽  
Dinalva A. Sales ◽  
Miriani G. Pastoriza ◽  
Daniel Ruschel-Dutra
Keyword(s):  
Active Galactic Nucleus ◽  
Seyfert Galaxies ◽  
Unified Model

scholarly journals Possible evidence of a universal radio/X-ray correlation in a near-complete sample of hard X-ray selected seyfert galaxies

2021 ◽  
Vol 503 (2) ◽  
pp. 1987-1998
Author(s):  
N Chang ◽  
F G Xie ◽  
X Liu ◽  
L C Ho ◽  
A-J Dong ◽  
...  
Keyword(s):  
Active Galactic Nucleus ◽  
Production Efficiency ◽  
Seyfert Galaxies ◽  
X Rays ◽  
Complete Sample ◽  
X Ray ◽  
Accretion Flow ◽  
Final Sample ◽  
Alternative Scenarios ◽  
Universal Correlation

ABSTRACT Because the disc–jet coupling likely depends on various properties of sources probed, the sample control is always an important but challenging task. In this work, we re-analysed the INTEGRAL hard X-ray-selected sample of Seyfert galaxies. We only consider sources that have measurements in black hole (BH) mass, and luminosities in radio and X-rays. Our final sample includes 64 (out of the original 79) sources, consists of both bright active galactic nucleus and low-luminosity ones. The 2–10 keV X-ray Eddington ratio LX/LEdd locates in the range between ∼10−4.5 and ∼10−0.5. We first find that, because of the similarity in the LHX/LX distribution, the X-ray origin of radio-loud Seyferts may be the same to that of radio-quiet (RQ) ones, where we attribute to the hot accretion flow (or similarly, the corona). We then investigate the connections between luminosities in radio and X-rays. Since our sample suffers a selection bias of a BH mass MBH dependence on LX/LEdd, we focus on the correlation slope ξX between the radio (at 1.4 GHz) and X-ray luminosities in Eddington unit, i.e. $({L_{\rm R}}/{L_{\rm Edd}}) \propto ({L_{\rm X}}/{L_{\rm Edd}})^{\xi _{\rm X}}$. We classify the sources according to various properties, i.e. 1) Seyfert classification, 2) radio loudness, and 3) radio morphology. We find that, despite these differences in classification, all the sources in our sample are consistent with a universal correlation slope ξX (note that the normalization may be different), with ξX = 0.77 ± 0.10. This is unexpected, considering various possible radio emitters in RQ systems. For the jet (either relativistic and well collimated, or sub-relativistic and weakly collimated) interpretation, our result may suggest a common/universal but to be identified jet launching mechanism among all the Seyfert galaxies, while properties like BH spin and magnetic field strength only play secondary roles. We further estimate the jet production efficiency ηjet of Seyfert galaxies, which is $\eta _{\rm jet}\approx 1.9^{+0.9}_{-1.5}\times 10^{-4}$ on average. We also find that ηjet increases as the system goes fainter. Alternative scenarios for the radio emission in RQ systems are also discussed.

scholarly journals Megamasers in Active Galactic Nuclei

1998 ◽  
Vol 11 (2) ◽  
pp. 938-941 ◽  
Author(s):  
R. J. Cohen
Keyword(s):  
Active Galactic Nuclei ◽  
Active Galactic Nucleus ◽  
Local Group ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Infrared Galaxies ◽  
Ultraluminous Infrared Galaxies

Extragalactic masers were discovered more than 20 years ago (Whiteoak & Gardner 1973). It soon became apparent that those extragalactic masers we can detect are intrinsically very powerful and are located in galactic nuclei. The term Megamaser was coined to describe the most luminous OH masers, which are a million times more powerful than any OH masers within our own Galaxy (Baan & Haschick 1984). The same word is nowadays applied to any powerful maser associated with an active galactic nucleus (AGN). Whereas normal Galactic masers would be barely detectable outside the Local Group, megamasers are detectable in principle out to redshifts of z ~ 2 (Baan 1997). The galaxies hosting megamasers in their nuclei are invariably active in some degree: they include ultraluminous infrared galaxies, starbursts and Seyfert galaxies.

A New Population of Highly Energetic Nuclear Transients

2017 ◽  
Vol 14 (S339) ◽  
pp. 131-134
Author(s):  
E. Kankare ◽  
R. Kotak ◽  
S. Mattila ◽  
P. Lundqvist
Keyword(s):  
Active Galactic Nucleus ◽  
Ambient Medium ◽  
Seyfert Galaxies ◽  
Energy Output ◽  
Broad Line ◽  
Spectral Evolution ◽  
Tidal Disruption ◽  
Broad Line Region ◽  
Supermassive Black Hole ◽  
Line Region

AbstractWe have identified a new population of luminous, optical, narrow-lined transients (FWHM ∼1000 km s−1) coincident with the nuclear region of Seyfert galaxies. According to extensive spectrophotometric follow-ups of the main event (PS1-10adi), we could exclude both normal active galactic nucleus activity and changing-look quasars as the origin. The integrated energy output and spectral evolution over a time-scale of several years point to two possible paths of origin: a tidal disruption of a star by a supermassive black hole, or an extremely energetic supernova occurring within the Seyfert galaxy’s narrow-line (or broad-line) region. The former model would require invoking a specific variant of a tidal disruption, while the latter would require an extremely efficient conversion of kinetic energy via shock interaction between the supernova ejecta and the dense ambient medium.

scholarly journals Constraining the Active Galactic Nucleus Contribution in a Multiwavelength Study of Seyfert Galaxies

2008 ◽  
Vol 689 (1) ◽  
pp. 95-107 ◽  
Author(s):  
M. Meléndez ◽  
S. B. Kraemer ◽  
H. R. Schmitt ◽  
D. M. Crenshaw ◽  
R. P. Deo ◽  
...  
Keyword(s):  
Active Galactic Nucleus ◽  
Seyfert Galaxies

scholarly journals SpitzerIRS Spectra of a Large Sample of Seyfert Galaxies: A Variety of Infrared Spectral Energy Distributions in the Local Active Galactic Nucleus Population

2006 ◽  
Vol 132 (1) ◽  
pp. 401-419 ◽  
Author(s):  
Catherine L. Buchanan ◽  
Jack F. Gallimore ◽  
Christopher P. O'Dea ◽  
Stefi A. Baum ◽  
David J. Axon ◽  
...  
Keyword(s):  
Active Galactic Nucleus ◽  
Seyfert Galaxies ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Large Sample ◽  
Infrared Spectral

scholarly journals TORUS AND ACTIVE GALACTIC NUCLEUS PROPERTIES OF NEARBY SEYFERT GALAXIES: RESULTS FROM FITTING INFRARED SPECTRAL ENERGY DISTRIBUTIONS AND SPECTROSCOPY

2011 ◽  
Vol 736 (2) ◽  
pp. 82 ◽  
Author(s):  
Almudena Alonso-Herrero ◽  
Cristina Ramos Almeida ◽  
Rachel Mason ◽  
Andrés Asensio Ramos ◽  
Patrick F. Roche ◽  
...  
Keyword(s):  
Active Galactic Nucleus ◽  
Seyfert Galaxies ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Infrared Spectral

The Extreme‐Ultraviolet Emission of the Seyfert Galaxies Markarian 279, Markarian 478, and Ton S180

1997 ◽  
Vol 475 (2) ◽  
pp. 552-556 ◽  
Author(s):  
Chorng‐Yuan Hwang ◽  
Stuart Bowyer
Keyword(s):  
Extreme Ultraviolet ◽  
Seyfert Galaxies ◽  
Ultraviolet Emission

Resonant Absorption in the Active Galactic Nucleus Spectra Emerging from Photoionized Gas: Differences between Steep and Flat Ionizing Continua

1999 ◽  
Vol 517 (1) ◽  
pp. 108-122 ◽  
Author(s):  
Fabrizio Nicastro ◽  
Fabrizio Fiore ◽  
Giorgio Matt
Keyword(s):  
Active Galactic Nucleus ◽  
Resonant Absorption
Sign in / Sign up

Export Citation Format

Share Document