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Stars embedded in the accretion disks of active galactic nuclei (AGN) can accrete rapidly from their surroundings, dramatically altering their structure and evolution. However, feedback from the release of gravitational potential energy and…

Solar and Stellar Astrophysics · Physics 2026-04-28 Alexander J. Dittmann , Matteo Cantiello

The accretion of matter onto celestial bodies like black holes and neutron stars is a natural phenomenon that releases up to $40\%$ of the matter's rest-mass energy, which is considered a source of radiation. In active galactic nuclei and…

High Energy Astrophysical Phenomena · Physics 2023-05-25 G. Abbas , Hamza Rehman , M. Usama , Tao Zhu

The X-ray properties of Active Galactic Nuclei (AGNs) depend on their underlying physical parameters, particularly the accretion rate. We identified eight reverberation-mapped AGNs with some of the largest known accretion rates without…

High Energy Astrophysical Phenomena · Physics 2024-01-17 Jaya Maithil , Michael S. Brotherton , Ohad Shemmer , Bin Luo , Pu Du , Jian-Min Wang , Hu Chen , Sarah C. Gallagher , Yan-Rong Li , Rodrigo S. Nemmen

We investigate the intrinsic spectral energy distribution (SED) of active galactic nuclei (AGNs) at infrared (IR) bands with 42 $z < 0.5$ optically luminous Palomar Green survey quasars through SED decomposition. We decompose the SEDs of…

Astrophysics of Galaxies · Physics 2020-05-06 Jun Xu , Mouyuan Sun , Yongquan Xue

We present a high density disc reflection spectral analysis of a sample of 17 Seyfert 1 galaxies to study the inner disc densities at different black hole mass scales and accretion rates. All the available XMM-Newton observations in the…

The interaction of a supermassive black hole with the matter of an accretion disk in the presence of a magnetic field is the key mechanism of energy release in active galactic nuclei. However, determining the physical parameters of this…

High Energy Astrophysical Phenomena · Physics 2023-10-10 M. Yu. Piotrovich , E. S. Shablovinskaya , E. A. Malygin , S. D. Buliga , T. M. Natsvlishvili

We perform an exploratory study of the physical properties of accretion flows and jets in low-luminosity active galactic nuclei (LLAGNs) by modeling the spectral energy distributions (SEDs) of 12 LLAGNs in low-ionization nuclear…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Rodrigo S. Nemmen , Thaisa Storchi-Bergmann , Michael Eracleous

We present the mean spectral energy distribution (SED) of a sample of optically selected quasars (QSOs) at redshifts of $1 \le z \le 5$. To derive it, we exploit photometric information from SDSS, UKIDSS, and WISE surveys in combination…

Astrophysics of Galaxies · Physics 2019-02-19 Federico Bianchini , Giulio Fabbian , Andrea Lapi , Joaquin Gonzalez-Nuevo , Roberto Gilli , Carlo Baccigalupi

Decomposing an arbitrary electron energy distribution into sums of Maxwellian and power law components is an efficient method to calculate synchrotron emission and absorption. We use this method to study the effect of non-thermal electrons…

High Energy Astrophysical Phenomena · Physics 2017-10-24 S. Alwin Mao , Jason Dexter , Eliot Quataert

We use the SOUX sample of $\sim$700 AGN to form average optical-UV-X-rays SEDs on a 2D grid of $M_{\mathrm{BH}}$ and $L_{2500}$. We compare these with the predictions of a new AGN SED model, QSOSED, which includes prescriptions for both hot…

Astrophysics of Galaxies · Physics 2023-06-28 Jake A. J. Mitchell , Chris Done , Martin J. Ward , Daniel Kynoch , Scott Hagen , Elisabeta Lusso , Hermine Landt

We study the observed relation between accretion rate (in terms of L/L_Edd) and shape of the hard X-ray spectral energy distribution (namely the photon index Gamma_X) for a large sample of 228 hard X-ray selected, low-redshift active…

The detection of X-ray emission constitutes a reliable and efficient tool for the selection of Active Galactic Nuclei (AGNs), although it may be biased against the most heavily absorbed AGNs. Simple mid-IR broad-band selection criteria…

Astrophysics of Galaxies · Physics 2020-05-06 E. Pouliasis , G. Mountrichas , I. Georgantopoulos , A. Ruiz , M. Yang , A. Z. Bonanos

There are strong suggestions that the disk-like accretion flow onto massive black hole in AGN is disrupted in its innermost part (10-100 Rg), possibly due to the radiation pressure instability. It may form a hot optically thin quasi…

Astrophysics · Physics 2009-10-31 B. Czerny , A. Abrassart , S. Collin-Souffrin , A. -M. Dumont

Most of the action in Active Galactic Nuclei (AGN) occurs within a few tens of gravitational radii from the supermassive black hole, where matter in the accretion disk may lose up to almost half of its energy with a copious production of…

We show how wavelength-dependent time delays between continuum flux variations of AGN can be used to test the standard black hole-accretion disc paradigm, by measuring the temperature structure $T(R)$ of the gaseous material surrounding the…

Astrophysics · Physics 2009-10-31 Stefan Collier , Kieth Horne , Ignaz Wanders , Bradley M. Peterson

$\require{mediawiki-texvc}$ We study accretion disk emission from eight Seyfert $1 - 1.5$ active galactic nuclei (AGN) using far ultra-violet ($1300-1800$ ${\AA}$) slit-less grating spectra acquired with AstroSat/UVIT. We correct for the…

High Energy Astrophysical Phenomena · Physics 2023-06-28 Shrabani Kumar , G. C. Dewangan , K. P. Singh , P. Gandhi , I. E. Papadakis , P. Tripathi , L. Mallick

Warped accretion discs in Active Galactic Nuclei (AGN) exert a torque on the black hole that tends to align the rotation axis with the angular momentum of the outer disc. We compute the magnitude of this torque by solving numerically for…

Astrophysics · Physics 2009-10-31 Priyamvada Natarajan , Philip J. Armitage

We investigate the central sub-arcsec region of the low-luminosity active galactic nucleus NGC 1052, using a high-angular resolution dataset that covers 10 orders of magnitude in frequency. This allows us to infer the continuum emission…

Astrophysics of Galaxies · Physics 2018-05-09 Lennart Reb , Juan A. Fernández-Ontiveros , M. Almudena Prieto , Klaus Dolag

Observations with the James Webb Space Telescope (JWST) have uncovered a substantial population of high-redshift, broad-line active galactic nuclei (AGNs), whose properties challenge standard models of black hole growth and AGN emission. We…

Astrophysics of Galaxies · Physics 2026-02-25 Greta Zucchi , Xihan Ji , Piero Madau , Roberto Maiolino , Ignas Juodžbalis , Francesco D'Eugenio , Sophia Geris , Yuki Isobe

Context: Accretion onto galactic and supermassive black holes occurs in different modes, which are documented in hard and soft spectral states, commonly attributed to an advection-dominated flow (ADAF) inside a truncated disk and standard…

Astrophysics · Physics 2009-11-11 F. Meyer , B. F. Liu , E. Meyer-Hofmeister