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8.4-GHZ radio imaging study of an optically selected sample of early type Seyfert galaxies; comparison of images taken at two epochs reveals possible variation in the nuclear radio flux density in five of them over a seven year period. It…

Cosmology and Nongalactic Astrophysics · Physics 2011-07-25 C. G. Mundell , N. Nagar , P. Ferruit

We develop a new spectral model for the broadband spectral energy distribution (SED) of Active Galactic Nuclei (AGN). This includes an outer standard disc, an inner warm Comptonising region to produce the soft X-ray excess and a hot corona.…

High Energy Astrophysical Phenomena · Physics 2018-08-01 Aya Kubota , Chris Done

We investigate the 1.4 GHz radio properties of 92 nearby (z<0.05) ultra hard X-ray selected Active Galactic Nuclei (AGN) from the Swift Burst Alert Telescope (BAT) sample. Through the ultra hard X-ray selection we minimise the biases…

Astrophysics of Galaxies · Physics 2016-05-04 O. Ivy Wong , M. J. Koss , K. Schawinski , A. D. Kapińska , I. Lamperti , K. Oh , C. Ricci , S. Berney

We present the evolutionary properties and luminosity functions of the radio sources belonging to the Chandra Deep Field South VLA survey, which reaches a flux density limit at 1.4 GHz of 43 microJy at the field center and redshift ~5, and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 P. Padovani , N. Miller , K. I. Kellermann , V. Mainieri , P. Rosati , P. Tozzi

(Abridged) In this article, we discuss the state of ``AGN feedback'' in radio-quiet (RQ) AGN. This study involves heterogeneous samples of nearby Seyfert and LINER galaxies as well as QSOs that have been observed at low radio frequencies…

Astrophysics of Galaxies · Physics 2023-02-15 Preeti Kharb , Silpa Sasikumar

We studied the broadband X-ray spectra of {\it Swift}/BAT selected low-accreting AGNs using the observations from {\it XMM-Newton}, {\it Swift}, and {\it NuSTAR} in the energy range of $0.5-150$~keV. Our sample consists of 30 AGNs with…

High Energy Astrophysical Phenomena · Physics 2023-07-26 Arghajit Jana , Arka Chatterjee , Hsiang-Kuang Chang , Prantik Nandi , Rubinur K. , Neeraj Kumari , Sachindra Naik , Samar Safi-Harb , Claudio Ricci

(Abridge) The relationship between coronal line (CL) emission and nuclear activity in active galactic nuclei (AGNs) is analyzed, for the first time, based on NIR spectra. The 8 CLs studied, of Si, S, Fe, Al and Ca elements and corresponding…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 A. Rodríguez-Ardila , M. A. Prieto , J. G. Portilla , J. M. Tejeiro

Several problems regarding the process of galaxy formation are still open. One of them is the role played by AGN phenomena in contributing to galaxy build-up and to Star Formation (SF) quenching. On the other hand, the theory of AGN…

Astrophysics of Galaxies · Physics 2015-04-15 Nicola Malavasi , Sandro Bardelli , Paolo Ciliegi , Olivier Ilbert , Lucia Pozzetti , Elena Zucca

We combine deep optical and radio data, from the Hyper Suprime-Cam and the Low-Frequency Array (LOFAR) respectively, to study 78 radio AGN in nearby (z<0.5) dwarf galaxies. Comparison to a control sample, matched in stellar mass and…

Astrophysics of Galaxies · Physics 2022-02-16 F. Davis , S. Kaviraj , M. J. Hardcastle , G. Martin , R. A. Jackson , K. Kraljic , K. Malek , S. Peirani , D. J. B. Smith , M. Volonteri , L. Wang

We studied the Active Galactic Nuclei (AGN) radio emission from a compilation of hard X-ray selected samples, all observed in the 1.4 GHz band. A total of more than 1600 AGN with 2-10 keV de-absorbed luminosities higher than 10^42 erg/s…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 F. La Franca , G. Melini , F. Fiore

We present the properties of accretion disk corona (ADC) models, where the radiation field, the temperature, and the total opacity of the corona are determined self-consistently. We use a non-linear Monte Carlo code to perform the…

Astrophysics · Physics 2009-10-30 James B. Dove , Jorn Wilms , Mitchell C. Begelman

We analysed how the active galactic nucleus (AGN) X-ray primary continuum depends on AGN activity in radio, using the data of RXTE Spectral & Timing Database (Rossi X-ray Timing Explorer) and INTEGRAL (INTErnational Gamma-Ray Astrophysics…

High Energy Astrophysical Phenomena · Physics 2017-06-13 E. Fedorova , A. Vasylenko , V. Zhdanov

Context. AGNs are strong X-ray emitters shaped by disk-corona interactions. The soft excess (0.5-2.0 keV) reveals key information about the "warm corona" bridging the disk and hot corona. Yet, how this feature evolves with accretion…

X-ray observations suggest high compactness of coronae in active galactic nuclei as well as in X-ray binaries. The compactness of the source implies a strong radial dependence in the illumination of the accretion disc. This will, for any…

High Energy Astrophysical Phenomena · Physics 2019-02-20 E. S. Kammoun , V. Domcek , J. Svoboda , M. Dovciak , G. Matt

We have surveyed two large samples of nearby low-luminosity AGN with the VLA to search for flat-spectrum radio cores, similar to Sgr A* in the Galactic Center. Roughly one third of all galaxies are detected (roughly one half if HII…

Astrophysics · Physics 2015-06-24 Heino Falcke , Neil M. Nagar , Andrew S. Wilson , Luis C. Ho , Jim S. Ulvestad

The thermal state of active galactic nucleus (AGN) coronae is commonly characterized by the electron temperature $kT_{\rm e}$, the Thomson optical depth $\tau$, and the geometry of the Comptonizing medium. We compile a literature sample of…

High Energy Astrophysical Phenomena · Physics 2026-05-13 Haichao Xu

Relativistic jets around supermassive black holes (SMBHs) are well-known powerful $\gamma$-ray emitters. In absence of the jets in radio-quiet active galactic nuclei (AGNs), how the SMBHs work in $\gamma$-ray bands is still unknown despite…

High Energy Astrophysical Phenomena · Physics 2025-06-25 Jun-Rong Liu , Jian-Min Wang , Fermi-LAT Collaboration

The basic mechanism responsible for radio emission in radio-loud active galactic nuclei (AGNs) is assumed to be synchrotron radiation. We suggest here that radio emission in radio-quiet objects is also due to synchrotron radiation of…

High Energy Astrophysical Phenomena · Physics 2015-05-20 W. Ishibashi , T. J. -L. Courvoisier

The origin of the radio emission in radio-quiet quasars (RQQs) remains unclear. Radio emission may be produced by a scaled-down version of the relativistic jets observed in radio-loud (RL) AGN, an AGN-driven wind, the accretion disc corona,…

Astrophysics of Galaxies · Physics 2021-12-08 R. D. Baldi , A. Laor , E. Behar , A. Horesh , F. Panessa , I. McHardy , A. Kimball

Galaxies which strongly deviate from the radio-far IR correlation are of great importance for studies of galaxy evolution as they may be tracing early, short-lived stages of starbursts and active galactic nuclei (AGNs). The most extreme…

Astrophysics of Galaxies · Physics 2016-10-26 F. Costagliola , R. Herrero-Illana , A. Lohfink , M. Pérez-Torres , S. Aalto , S. Muller , A. Alberdi
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