Results 41 to 50 of about 50,261 (220)
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
Radiation pressure acceleration by X-rays in active galactic nuclei [PDF]
Monthly Notices of the Royal Astronomical Society, 2001 We present calculations of the dynamics of highly ionized gas clouds that are confined by external pressure, and are ionized by AGN continuum. We focus on the gas that is seen in absorption in the X-ray spectrum of many AGN and show that such gas can reach hydrostatic equilibrium under various conditions. The principal conclusion is that the clouds can
Chelouche, Doron, Netzer, Hagai
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Advanced Science, EarlyView.A real‐time, non‐contact photoplethysmography (PPG) system based on InAs colloidal quantum dots (CQDs) synthesized via a seedless injection synthesis is demonstrated. The measured oxygen saturation shows considerable agreement with commercial PPG devices.
Beom Kwan Kim +8 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
Advanced Science, EarlyView.Inspired by natural amino acid polymer‐melanin systems, this study strategically incorporated tellurocysteine to develop advanced radiation‐shielding materials. This approach transformed the primary interaction mechanism between melanin‐based materials and incident photons from Compton scattering to the photoelectric effect. Tellurocysteine‐polymerized
Wei Chen +6 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
Astronomische Nachrichten, EarlyView.ABSTRACT The goal of this study is to confirm the feasibility of the use of digitized low dispersive MtWilson Michigan Southern Sky Hα$$ \alpha $$ survey astronomical photographic plates for modern astrophysical research. The detection of highly redshifted objects, such as early galaxies and quasars, is fundamental to understanding the universe's ...
Tauseef Ahmad Zafar +3 more
wiley +1 more source
The NH Distribution of Hard X-Ray Selected Active Galactic Nuclei in the NEP Field
The Astrophysical JournalX-ray surveys are one of the most unbiased methods for detecting Compton-thick (CT; N _H ≥ 10 ^24 cm ^−2 ) active galactic nuclei (AGN), which are thought to comprise up to 60% of AGN within z ≲ 1.0.
Samantha Creech +11 more
doaj +1 more source
The Astrophysical Journal Letters, 2023 Recent studies have proposed that the nuclear millimeter continuum emission observed in nearby active galactic nuclei (AGNs) could be created by the same population of electrons that gives rise to the X-ray emission that is ubiquitously observed in ...
Claudio Ricci +12 more
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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.
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