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Galaxies with active galactic nuclei (AGN) exhibit broad emission lines as a key spectral feature. The shape of emission-line profiles depends on the complex dynamics of discrete clouds within a spatially extended region known as the Broad…

Astrophysics of Galaxies · Physics 2025-10-08 M. H. Naddaf , M. L. Martinez-Aldama , D. Hutsemekers , D. Savic , B. Czerny

The dynamics of the Broad Line Region (BLR) in Active galaxies is an open question, direct observational constraints suggest a predominantly Keplerian motion, with possible traces of inflow or outflow. In this paper we study in detail the…

Astrophysics of Galaxies · Physics 2021-10-20 Mohammad-Hassan Naddaf , Bozena Czerny , Ryszard Szczerba

Broad Emission Lines are the most characteristic features of Active Galaxies, but the mechanism of creating a medium able to emit these intense lines is not quite clear. Observations clearly indicate that the motion of the material is…

Astrophysics of Galaxies · Physics 2019-09-19 Bozena Czerny

The most characteristic property of active galaxies, including quasars, are prominent broad emission lines. I will discuss an interesting possibility that dust is responsible for this phenomenon. The dust is known to be present in quasars…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Bozena Czerny , Krzysztof Hryniewicz , Janusz Kaluzny , Ishita Maity

In this work we analyze a sample of AGN spectra, selected from the 6th Data Release of the Sloan Digital Sky Survey, exploiting a generalized technique of line profile analysis, designed to take into account the whole profiles of their…

Astrophysics · Physics 2011-02-11 G. La Mura , F. Di Mille , S. Ciroi , L. Č. Popović , P. Rafanelli

The origin of the Broad Line Region (BLR) in active galaxies remains unknown. It seems to be related to the underlying accretion disk but an efficient mechanism is required to rise the material from the disk surface without giving too…

Astrophysics of Galaxies · Physics 2016-11-23 Bozena Czerny , Pu Du , Jian-Min Wang , Vladimir Karas

The spectra of active galactic nuclei exhibit broad-emission lines that presumably originate in the Broad-Line Region (BLR) with gaseous-dusty clouds in a predominantly Keplerian motion around the central black hole. Signatures of both…

High Energy Astrophysical Phenomena · Physics 2022-06-01 Ana Laura Müller , Mohammad-Hassan Naddaf , Michal Zajaček , Bożena Czerny , Anabella Araudo , Vladimír Karas

The remarkable similarity between emission spectra of narrow line regions (NLR) in Seyfert Galaxies has long presented a mystery. In photoionization models, this similarity implies that the ionization parameter is nearly always the same,…

Astrophysics · Physics 2009-11-07 M. A. Dopita , B. A. Groves , R. S. Sutherland , L. Binette , G. Cecil

The broad-line region (BLR) of active galactic nuclei (AGN) is an essential component, yet its small size keeps its origin, structure, and kinematics uncertain. Infrared interferometry with VLTI/GRAVITY is now resolving BLR-scale emission,…

Astrophysics of Galaxies · Physics 2026-03-12 Keiichi Wada , Tohru Nagao , Taro Shimizu , Daryl Joe D. Santos , Jinyi Shangguan , Richard Davies

We propose a very simple physical mechanism responsible for the formation of the Low Ionization Line part of the Broad Line Region in Active Galactic Nuclei. It explains the scaling of the Broad Line Region size with the monochromatic…

Active galactic nuclei (AGN) are characterized by similar broad emission lines properties at all luminosities ($10^{39}$-$10^{47}$ erg s$^{-1}$). What produces this similarity over a vast range of $10^8$ in luminosity? Photoionization is…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-04 Alexei Baskin , Ari Laor , Jonathan Stern

The profiles of the broad emission lines of active galactic nuclei (AGNs) and the time delays in their response to changes in the ionizing continuum ("lags") give information about the structure and kinematics of the inner regions of AGNs.…

High Energy Astrophysical Phenomena · Physics 2018-04-18 C. Martin Gaskell , Peter Z. Harrington

(Abridged) We investigate the observational characteristics of BLR geometries in which the BLR clouds bridge the gap, both in distance and scale height, between the outer accretion disc and the hot dust, forming an effective surface of a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 M. R. Goad , K. T. Korista , A. J. Ruff

Strong broad emission lines are the most important signatures of active galactic nuclei. These lines allowed to discover the cosmological nature of quasars, and at present these lines allow for convenient method of weighting the black holes…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 B. Czerny , K. Hryniewicz

Context. Dust in active galactic nuclei is clearly present right outside the broad-line region (BLR) in the form of a dusty molecular torus. However, some models of the BLR predict that dust may also exist within the BLR. Aims. We study the…

Broad-line regions (BLR) are one of the main components that constitute the phenomenological picture of active galaxies near the vicinity of the accreting supermassive black holes. Both theoretical and observational studies have shown that…

High Energy Astrophysical Phenomena · Physics 2019-11-13 Swayamtrupta Panda

The strong broad emission lines in the optical and UV spectra of Active Galactic Nuclei (AGN) are important for several reasons. Not only do they give us information about the structure of the AGN, their properties are now used to estimate…

Astrophysics · Physics 2007-05-23 Karen M. Leighly , Darrin Casebeer

We present a new analysis of the motion of broad line region (BLR) clouds in active galactic nuclei (AGNs) taking into account the combined influence of gravity and radiation pressure force. We calculate cloud orbits under a large range of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Hagai Netzer , Paola Marziani

This paper presents a preliminary investigation into the influence of radial behavior of disk outflow on the structure and dynamics of the broad line region (BLR) in active galactic nuclei (AGNs), with the emphasis on how the mass ejection…

Astrophysics of Galaxies · Physics 2024-12-30 Mohammad Hassan Naddaf

We investigate orbital motion of spherical, pressure-confined clouds in the broad-line region (BLR) of active galactic nuclei (AGN). The combined influence of gravity of the central object and the non-isotropic radiation of the central…

Astrophysics of Galaxies · Physics 2015-06-23 Fazeleh Khajenabi
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