Results 1 to 10 of about 200 (175)
Morphology of Seyfert galaxies [PDF]
Astrophysics and Space Science, 2017 We probed the relation between properties of Seyfert nuclei and morphology of their host galaxies. We selected Seyfert galaxies from the Sloan Digital Sky Survey with redshifts less 0.2 identified by the Véron Catalog (13th). We used the "{\it{FracDev}}" parameter from SDSS galaxy fitting models to represent the bulge fractions of the Seyfert host ...
Chorng-Yuan Hwang
exaly +3 more sources
A spectropolarimetric atlas of Seyfert 1 galaxies [PDF]
Monthly Notices of the Royal Astronomical Society, 2002 We present optical spectropolarimetry of the nuclei of 36 Seyfert 1 galaxies, obtained with the William Herschel and the Anglo-Australian Telescopes from 1996 to 1999. In 20 of these, the optical emission from the active nucleus is intrinsically polarized.
D J Axon, J H Hough, Smith J E
exaly +3 more sources
Narrow-line Seyfert 1 galaxies and the evolution of galaxies and active galaxies [PDF]
Monthly Notices of the Royal Astronomical Society, 2000 Narrow Line Seyfert 1 galaxies (NLS1s) are intriguing due to their continuum as well as emission line properties. The observed peculiar properties of the NLS1s are believed to be due to accretion rate close to Eddington limit. As a consequence, for a given luminosity, NLS1s have smaller black hole (BH) masses compared to normal Seyfert galaxies.
S Mathur, Smita Mathur, Mathur Smita
exaly +3 more sources
Decomposition of the central structure of NGC 2273 in the NIR: A case study
Astronomische Nachrichten, Volume 344, Issue 10, December 2023., 2023 Abstract The Seyfert 2 galaxy NGC 2273 is a prime target to explore how active nuclei can be fed. It has a star‐forming innermost nuclear ring with a radius of 0.33kpc from where material may be funneled to the supermassive black hole in its center. In this article, we discuss high‐resolution adaptive optics aided JHKs images of NGC 2273 taken with the
L. Schey +13 more
wiley +1 more source
A tool to understand emission mechanisms of blazars through their high‐energy gamma‐ray emission
Astronomische Nachrichten, Volume 344, Issue 6, August 2023., 2023 The blazar SED is characterized by two energy components. Evidence suggests that the low‐energy component is generated by the synchrotron mechanism, but for the high‐energy component, the mechanism is still uncertain. Two main models have been proposed to explain this emission. According to the leptonic model, a correlation between the emission of both
Mabel Osorio +3 more
wiley +1 more source
Unraveling the enigmatic soft x‐ray excess: Current understanding and future perspectives
Astronomische Nachrichten, Volume 344, Issue 6, August 2023., 2023 Abstract This article explores various theoretical models proposed to explain the soft x‐ray excess phenomenon, including warm Comptonization, ionized reflection models, and ionized outflowing disc winds. The soft x‐ray excess is better understood thanks to crucial observations made by ROSAT, XMM‐Newton, and eROSITA.
Thomas Boller
wiley +1 more source
Searching for overlooked TDEs in the 4XMM catalogue
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract Tidal disruption events (TDEs) are usually discovered as bright transients, either in the X‐ray or optical/UV band. These events are often characterized by a “super‐soft” emission in the X‐ray band, which has not been observed in any other extragalactic source, with few exceptions (novae and supersoft active galactic nuclei, AGN), which can ...
Andrea Sacchi +2 more
wiley +1 more source
Extreme accretion events: TDEs and changing‐look AGN
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract We present a review of the topics of X‐ray stellar tidal disruption events (TDEs) and changing‐look active galactic nuclei (AGN). Stars approaching a supermassive black hole (SMBH) can be tidally disrupted and accreted. TDEs were first discovered in the X‐ray regime and appear as luminous, giant‐amplitude flares from inactive galaxies.
S. Komossa, D. Grupe
wiley +1 more source
Nested and Single Bars in Seyfert and Non‐Seyfert Galaxies [PDF]
The Astrophysical Journal, 2002 33 pages, including 23 postscript figures, fixed a problem with deprojected position angle profiles and the resulting bar classifications and statistics numbers and figures and tables, to appear in ...
Laine, Seppo +3 more
openaire +4 more sources
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract Radiation‐magnetohydrodynamic simulation of the active galactic nuclei predicts the presence of the strong accretion disk wind, which gets unstable far from the central region and turns into gas clumps. These inner wind and outer clumps may be actually observed as the ultrafast outflows (UFOs) and the clumpy absorbers, respectively.
Takuya Midooka +2 more
wiley +1 more source