Results 11 to 20 of about 63,914 (268)
Rapid X-Ray Variability in Active Galactic Nuclei [PDF]
Symposium - International Astronomical Union, 1986 SummaryRecent EXOSAT observations of active galactic nuclei are presented. Unlike earlier X-ray satellites (all of which flew in low earth orbit), the deep orbit of EXOSAT allows long continuous observations of celestial X-ray sources, uninterrupted by earth occultation etc.
P. Barr +4 more
openaire +1 more source
The Astrophysical Journal, 2023 We report on the 2019 XMM-Newton+NuSTAR monitoring campaign of the Seyfert galaxy NGC 2992, observed at one of its highest flux levels in the X-rays.
Alfredo Luminari +10 more
doaj +1 more source
Clustering of X-ray selected active galactic nuclei [PDF]
Monthly Notices of the Royal Astronomical Society, 1998 A total of 235 Active Galactic Nuclei (AGN) from two different soft X-ray surveys (the ROSAT Deep Survey -DRS- and the ROSAT International X-ray Optical Survey -RIXOS-) with redshifts between 0 and 3.5 are used to study the clustering of X-ray selected AGN and its evolution.
Carrera, Francisco J. +7 more
openaire +3 more sources
LoCuSS: A DYNAMICAL ANALYSIS OF X-RAY ACTIVE GALACTIC NUCLEI IN LOCAL CLUSTERS [PDF]
, 2012 We present a study of the distribution of X-ray active galactic nuclei (AGNs) in a representative sample of 26 massive clusters at 0.15 < z < 0.30, combining Chandra observations sensitive to X-ray point sources of luminosity LX ∼ 1042 erg s−1 at the ...
C. Haines +10 more
semanticscholar +1 more source
The Astrophysical Journal, 2023 “Changing-look active galactic nuclei” (CLAGNs) are known to change their apparent types between types 1 and 2, usually accompanied by a drastic change in their luminosity on timescales of years.
Hirofumi Noda +13 more
doaj +1 more source
X-Ray Observations of Active Galactic Nuclei [PDF]
Symposium - International Astronomical Union, 1983 HEAO 1 A2 and Einstein SSS spectral observations of Seyfert galaxies and BL Lac objects suggest that in both cases, the X-ray emission is due to relativistic particles. The five BL Lac objects have very soft spectra and at higher energies (above 10 keV) may have hard tails.
C. Megan Urry +4 more
openaire +1 more source
Cosmological Evolution of the Hard X-Ray Active Galactic Nucleus Luminosity Function and the Origin of the Hard X-Ray Background [PDF]
, 2003 We investigate the cosmological evolution of the hard X-ray luminosity function (HXLF) of active galactic nuclei (AGNs) in the 2-10 keV luminosity range of 1041.5-1046.5 ergs s-1 as a function of redshift up to 3.
Y. Ueda, M. Akiyama, K. Ohta, T. Miyaji
semanticscholar +1 more source
X-Ray Variability of Active Galactic Nuclei [PDF]
Highlights of Astronomy, 1983 X-ray variability of active galactic nuclei is commonplace on scales from days to years. It also occurs, although rarely, on time scales as short as 200 seconds. Both these statements must be strongly qualified by the irregularity and insensitivity of the available observations. In the X-rays we expect that we are seeing deep within the active nucleus,
Daniel A. Schwartz +2 more
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LUMINOUS X-RAY ACTIVE GALACTIC NUCLEI IN CLUSTERS OF GALAXIES [PDF]
, 2010 We present a study of X-ray active galactic nucleus (AGN) overdensities in 16 Abell clusters, within the redshift range 0.073 < z < 0.279, in order to investigate the effect of the hot inter-cluster environment on the triggering of the AGN phenomenon ...
E. Koulouridis, M. Plionis
semanticscholar +1 more source
Low-Luminosity X-Ray Active Galactic Nuclei in S0 Galaxies NGC 3065 and NGC 4203 [PDF]
, 1998 We present ASCA X-ray results on two S0 galaxies, NGC 3065 and NGC 4203. In both galaxies, we detected hard X-ray emission from a pointlike source at the nucleus.
N. Iyomoto +5 more
semanticscholar +1 more source