Results 61 to 70 of about 63,914 (268)
The X-Ray Polarization of the Accretion Disk Coronae of Active Galactic Nuclei [PDF]
, 2017 Hard X-rays observed in Active Galactic Nuclei (AGNs) are thought to originate from the Comptonization of the optical/UV accretion disk photons in a hot corona.
B. Beheshtipour +2 more
semanticscholar +1 more source
Hidden No More: Spotlight on Tidal Disruption Events in Active Galactic Nuclei
Astronomische Nachrichten, EarlyView.ABSTRACT Tidal disruption events (TDEs) are typically discovered in previously quiescent galaxies. However, earlier studies have revealed a handful of TDEs occurring in pre‐existing active galactic nuclei (AGN). We discuss AT2019aalc, a promising TDE candidate in an AGN, and compare it to similar sources.
Patrik Milán Veres
wiley +1 more source
Fast X-Ray Variability from the Coronae of Supermassive Black Holes
The Astrophysical Journal LettersWe present the first systematic study of short-timescale X-ray variability in radio-quiet active galactic nuclei (AGN), utilizing archival Chandra observations of approximately 3000 broad-line AGN selected from the Sloan Digital Sky Survey and Dark ...
Xiurui Zhao +6 more
doaj +1 more source
A Comparison of the X-Ray Emission from Tidal Disruption Events with those of Active Galactic Nuclei [PDF]
, 2017 One of the main challenges of current tidal disruption events (TDEs) studies is that emission arising from active galactic nucleus (AGN) activity may potentially mimic the expected X-ray emission of a TDE. Here we compare the X-ray properties of TDEs and
K. Auchettl +2 more
semanticscholar +1 more source
Early evolutionary history of the seed
Biological Reviews, EarlyView.ABSTRACT The seed is an essential stage in the life history of gymnospermous and angiospermous plants, facilitating both their survival and dispersal. We reappraise knowledge of the evolutionary history of the gymnospermous seed, from its origin in the late Devonian through to the well‐known end‐Permian extinctions – an interval encompassing the ...
Richard M. Bateman +2 more
wiley +1 more source
The Astrophysical JournalA core sample of 59 unobscured type 1 active galactic nuclei (AGNs) with simultaneous XMM-Newton X-ray and UV observations is compiled from the archives to probe the nature of soft X-ray excess (SE).
Shi-Jiang Chen +7 more
doaj +1 more source
The X-Ray Coronae in NuSTAR Bright Active Galactic Nuclei
The Astrophysical Journal, 2022 Abstract We present a systematic and uniform analysis of NuSTAR data of a sample of 60 SWIFT BAT-selected AGNs with 10–78 keV signal-to-noise ratio (S/N) > 50, 10 of which are radio loud. We measure their high-energy cutoff E cut or coronal temperature T e using three different spectral models to ...
Jia-Lai Kang, Jun-Xian Wang
openaire +2 more sources
Experimental methods in chemical engineering: Atomic absorption spectrometry—AAS
The Canadian Journal of Chemical Engineering, EarlyView.Abstract Elements absorb electromagnetic radiation (light) of a specific wavelength in proportion to the number of atoms in its path. As the atoms absorb this light energy, electrons rise from the ground state to an excited state. In atomic absorption spectrometry (AAS), high temperatures produce clouds of atoms from the sample (atomization) and ...
Emily Cintia Tossi de A. Costa +4 more
wiley +1 more source
The Astrophysical JournalWe conduct precise measurements of active galactic nucleus (AGN) clustering at z ∼ 1 and z ∼ 2 by measuring the two-point cross-correlation function (CCF) between galaxies and X-ray-selected AGNs, and the two-point autocorrelation function (ACF) of ...
Hiroyuki Ikeda +8 more
doaj +1 more source
X-ray absorption in Active Galactic Nuclei
, 2007 10 pages, 4 figures, Conference proceedings to appear in "The Central Engine of Active Galactic Nuclei", ed. L. C. Ho and J.-M. Wang (San Francisco: ASP)
Maiolino, R., Risaliti, G.
openaire +2 more sources