Results 31 to 40 of about 64,814 (288)
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
A Catalog of AGN Host Galaxies Observed with HST/ACS: Correlations between Star Formation and AGN Activity [PDF]
Astrophysical Journal, 2019 We present the Advanced Camera for Surveys Active Galactic Nuclei (ACS-AGN) Catalog, a catalog of 2585 active galactic nucleus (AGN) host galaxies that are at redshifts 0.2 < z < 2.5 and that were imaged with the Hubble Space Telescope’s Advanced Camera ...
A. Stemo +6 more
semanticscholar +1 more source
Relation between AGN type and host galaxy properties [PDF]
Astronomy & Astrophysics, 2021 We use 3213 active galactic nuclei (AGNs) from the XMM-XXL northern field to investigate the relation of AGN type with host galaxy properties. Applying a Bayesian method, we derive the hardness ratios, and through these the hydrogen column density (NH) for each source. We consider those with NH > 1021.5 cm−2 as absorbed sources (type 2).
M. Plionis +3 more
openaire +5 more sources
Fourier spectral‐timing techniques for the study of accreting black holes
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract The X‐ray signal from active galactic nuclei and black hole (BH) X‐ray binaries is highly variable on a range of timescales. This variability can be exploited to map the region of interest close to the BH, which is far too small to directly image for all but two BHs in the Universe.
Adam Ingram
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
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract The non‐linear correlation between the UV and X‐ray emission observed in active galactic nuclei remains a puzzling question that challenges accretion models. While the UV emission originates from the cold disk, the X‐ray emission is emitted by a hot corona whose physical characteristics and geometry are still highly debated.
S. Barnier +3 more
wiley +1 more source
[O ii] as a proxy for star formation in AGN host galaxies: beware of extended emission line regions [PDF]
Monthly notices of the Royal Astronomical Society, 2018 The [OII] 3726+3728\AA\ emission line doublet is often used to estimate star formation rates within the host galaxies of active galactic nuclei (AGN), as it is known to be strongly excited by star formation, but is only weakly excited in the broad and ...
N. Maddox
semanticscholar +1 more source
The hyperluminous X‐ray source population
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract We have recently published a catalog of 1843 candidate ultraluminous X‐ray sources (ULXs). This is the largest catalog of ULXs to date and was built by cross‐correlating recent serendipitous source catalogs from the XMM‐Newton, Swift, and Chandra observatories with a large sample of galaxies, primarily from HyperLEDA.
A. D. A. MacKenzie +2 more
wiley +1 more source
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
Overmassive Black Holes in Dwarf Galaxies Out to z ∼ 0.9 in the VIPERS Survey
The Astrophysical Journal Letters, 2023 Supermassive black holes (SMBHs) are thought to originate from early universe seed black holes of mass M _BH ∼ 10 ^2 –10 ^5 M _⊙ and grown through cosmic time. Such seeds could be powering the active galactic nuclei (AGN) found in today’s dwarf galaxies.
Mar Mezcua +5 more
doaj +1 more source