Results 41 to 50 of about 274,748 (260)
Active Galactic Nuclei Unification and the X‐Ray Background [PDF]
The Astrophysical Journal, 2005 Active galactic nuclei (AGNs) unification, which implies a large number of obscured AGNs, can explain the optical, infrared, and X-ray content of deep multiwavelength surveys. Here we show that the same model also successfully explains the spectral shape and intensity of the X-ray background. The simplest possible unified model assumes a constant ratio
Ezequiel Treister +2 more
openaire +3 more sources
Review on Active-Galactic Nuclei at hard X-ray energies [PDF]
Proceedings of An INTEGRAL view of the high-energy sky (the first 10 years) - 9th INTEGRAL Workshop and celebration of the 10th anniversary of the launch — PoS(INTEGRAL 2012), 2013 Hard X-ray surveys are an important tool for the study of active galactic nuclei (AGN): they provide almost an unbiased view of absorption in the extragalactic population, allow the study of spectral features such as reflection and high energy cut-off which would otherwise be unexplored and favour the discovery of some blazars at high redshift.
R. Landi +8 more
openaire +2 more sources
AGN STORM 2. III. A NICER View of the Variable X-Ray Obscurer in Mrk 817
The Astrophysical Journal, 2023 The AGN STORM 2 Collaboration targeted the Seyfert 1 galaxy Mrk 817 for a year-long multiwavelength, coordinated reverberation mapping campaign including Hubble Space Telescope, Swift, XMM-Newton, NICER, and ground-based observatories. Early observations
Ethan R. Partington +48 more
doaj +1 more source
X-rays from active galactic nuclei
The Astrophysical Journal, 1981 Through detailed numerical calculations, we have shown that production of thermal photons at the self-absorbed cyclotron higher harmonics and Comptonization of those soft photons in a hot plasma with the electron temperature 10/sup 9/ K provide a natural mechanism to account for the dominant observed features of the X-ray emission in the active ...
Sachiko Tsuruta +2 more
openaire +2 more sources
The Most Obscured AGNs in the XMM-SERVS Fields
The Astrophysical Journal, 2023 We perform X-ray spectral analyses to derive the characteristics (e.g., column density, X-ray luminosity) of ≈10,200 active galactic nuclei (AGNs) in the XMM-Spitzer Extragalactic Representative Volume Survey, which was designed to investigate the growth
Wei Yan +11 more
doaj +1 more source
X-ray variability time scales in active galactic nuclei [PDF]
Astronomy & Astrophysics, 2009 6 pages, 1 figure, accepted for publication in Astronomy and ...
W. Ishibashi, T. J. L. Courvoisier
openaire +3 more sources
X-ray bolometric corrections for Compton-thick active galactic nuclei [PDF]
, 2017 We present X-ray bolometric correction factors, $\kappa_{Bol}$ ($\equiv L_{Bol}/L_X$), for Compton-thick (CT) active galactic nuclei (AGN) with the aim of testing AGN torus models, probing orientation effects, and estimating the bolometric output of the ...
Ballantyne, D. R. +18 more
core +4 more sources
The Astrophysical Journal Supplement Series, 2022 Virial black hole (BH) mass ( M _BH ) determination directly involves knowing the broad-line region (BLR) clouds’ velocity distribution, their distance from the central supermassive BH ( R _BLR ), and the virial factor ( f ). Understanding whether biases
Federica Ricci +26 more
doaj +1 more source
Ultraviolet and X-ray variability of active galactic nuclei withSwift [PDF]
Monthly Notices of the Royal Astronomical Society, 2016 14 pages, 8 figures, 4 tables in main text, plus 15 pages of figures in appendices.
D. J. K. Buisson +3 more
openaire +3 more sources
X-ray Properties of Radio-Selected Dual Active Galactic Nuclei [PDF]
, 2019 Merger simulations predict that tidally induced gas inflows can trigger kpc-scale dual active galactic nuclei (dAGN) in heavily obscured environments. Previously with the Very Large Array, we have confirmed four dAGN with redshifts between $0.04 < z < 0 ...
Djorgovski, S . G. +4 more
core +2 more sources