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We study orbit of a pressure-confined cloud in the broad-line region (BLR) of active galactic nuclei (AGNs) when the combined effects of the central gravity and anisotropic radiation pressure and the drag force are considered. Physical…

Astrophysics of Galaxies · Physics 2015-06-02 Mohsen Shadmehri

We calculated the polarization degree of hydrogen Balmer broad emission lines from a number of active galactic nuclei (AGNs) with determined virial factors. The objects were selected from the sample presented by Decarli et al.(2008). In our…

Astrophysics of Galaxies · Physics 2017-03-27 M. Yu. Piotrovich , Yu. N. Gnedin , T. M. Natsvlishvili , S. D. Buliga

We have mapped the CO(3-2) line emission from several nearby galaxies, using the Heinrich-Hertz-Telescope. Our investigation includes twelve galaxies of various types and in different stages of star forming activity. The main results of…

Astrophysics · Physics 2016-08-30 M. Dumke , Ch. Nieten , G. Thuma , R. Wielebinski , W. Walsh

A combined analysis of the profiles of the main broad quasar emission lines in both Hubble Space Telescope and optical spectra shows that while the profiles of the strong UV lines are quite similar, there is frequently a strong increase in…

Astrophysics · Physics 2017-02-22 Stephanie A. Snedden , C. Martin Gaskell

We analyze the broad H$\beta$ line profile variability of the "changing look" active galactic nucleus (CL-AGN) NGC 3516 over a long period of 25 years. The observed change in the broad line profile may indicate a change in the geometry of…

We investigate general aspects of molecular line formation under conditions which are typical of prestellar cores. Focusing on simple linear molecules, we study formation of their rotational lines by radiative transfer simulations. We…

Astrophysics · Physics 2009-11-13 Ya. Pavlyuchenkov , D. Wiebe , B. Shustov , Th. Henning , R. Launhardt , D. Semenov

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

It has been recently proposed that the broad line region in active galactic nuclei originates from dusty clouds driven from the accretion disk by radiation pressure, at a distance from the black hole where the disk is cooler than the dust…

Astrophysics of Galaxies · Physics 2015-06-16 Pasquale Galianni , Keith Horne

We present the results of the long-term optical monitoring campaign of active galactic nuclei (AGN) coordinated by the Special Astrophysical Observatory of the Russian Academy of Science. This campaign has produced a remarkable set of…

Models of active galactic nuclei often invoke a close physical association between the broad-line region and the accretion disk. We evaluate this theoretical expectation by investigating the relationship between the inclination angle of the…

High Energy Astrophysical Phenomena · Physics 2025-07-14 Rong Du , Luis C. Ho , Yuanze Ding , Ruancun Li

The spectral variability of active galactic nuclei (AGN) is one of their key features that enables us to study in more details the structure of AGN emitting regions. Especially, the broad line profiles, that vary both in flux and shape,…

Astrophysics of Galaxies · Physics 2016-01-20 D. Ilic , L. C. Popovic , A. I. Shapovalova , A. N. Burenkov , V. H. Chavushyan , A. Kovacevic

Strong both broad and narrow emission lines from central broad emission line regions (BLRs) and narrow emission line regions (NLRs) are fundamental spectroscopic characteristics of broad line Active Galactic Nuclei (BLAGNs). Lack of central…

Astrophysics of Galaxies · Physics 2025-06-24 Zhang XueGuang

Long and short gamma-ray bursts are traditionally associated with galactic environments, where circumburst densities are small or moderate (few to hundreds of protons per cubic cm). However, both are also expected to occur in the disks of…

High Energy Astrophysical Phenomena · Physics 2022-10-26 Davide Lazzati , Gustavo Soares , Rosalba Perna

Here I describe recent studies of objects with molecular hydrogen emission that is strong relative to other spectral lines. Large telescopes and fast spectrometers have made the 2 {\mu}m window accessible even for relatively faint objects.…

Cosmology and Nongalactic Astrophysics · Physics 2011-07-25 Gary J. Ferland

B[e] supergiants (B[e]SGs) are emission-line objects, presumably in a short-lived phase in the post-main sequence evolution of massive stars. Their intense infrared excess emission indicates large amounts of warm circumstellar dust, and the…

Solar and Stellar Astrophysics · Physics 2016-10-18 Michaela Kraus

The first radio surveys of the sky discovered that some large clusters of galaxies contained powerful sources of synchrotron emission. Optical images showed that long linear filaments with bizarre emission-line spectra permeated the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Gary J. Ferland

Adopting a spherically symmetric steady-state ballistic inflow as the kinematic model for the gas distribution responsible for producing the H{\alpha} emission line and a central black hole (BH) mass of 1.7 x10^6 M_sun, determined from…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Nick Devereux , Emily Heaton

We used the $H\alpha$ images from a large sample of nearby late-type dwarf galaxies to investigate properties of their emission structure. The sample consists of three hundred galaxies of the irregular (Irr), Magellanic irregular (Im), blue…

Astrophysics of Galaxies · Physics 2020-12-16 Karachentsev I. D. , Kaisin S. S

Emission lines formed in the circumstellar envelopes of several type of stars can be modeled using first principles of line formation. We present simple ways of calculating line emission profiles formed in circumstellar envelopes having…

Astrophysics · Physics 2016-08-15 M. L. Arias , J. Zorec , Y. Frémat

This is the eighth in a series of papers reporting on a large reverberation mapping campaign to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). We employ the recently developed dynamical modeling approach…

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