Results 151 to 160 of about 289,816 (297)
QPO in RE J1034+396: model constraints from observed trends
, 2012 We analyze the time variability of the X-ray emission of RE J1034+396, an active galactic nucleus with the first firm detection of a quasi-periodic oscillations (QPO).
Czerny, B. +5 more
core +1 more source
AGU Advances, Volume 6, Issue 2, April 2025.Abstract Calderas often experience extended periods of unrest that are challenging to relate to a magmatic or hydrothermal origin, making it crucial to assemble a clear picture of these dynamics. Since 2005, Campi Flegrei caldera (Italy) has experienced accelerating ground uplift, seismicity rates, and degassing.
Gianmarco Buono +10 more
wiley +1 more source
The Astrophysical Journal LettersQuasiperiodic oscillations (QPOs) have been widely observed in black hole X-ray binaries (BHBs), which often exhibit significant X-ray variations. Extensive research has explored the long-term evolution of the properties of QPOs in BHBs.
Ruisong Xia, Hao Liu, Yongquan Xue
doaj +1 more source
A ~1-hour X-ray periodicity in an active galaxy RE J1034+396 [PDF]
arXiv, 2008 Active galactic nuclei and quasars are thought to be scaled up versions of Galactic black hole binaries, powered by accretion onto supermassive black holes with masses of 10^6-10^9 M_Sun, as opposed to the ~10 M_Sun in binaries. One example of the similarities between these two types of systems is the characteristic rapid X-ray variability seen from ...
arxiv
X-ray emission from active galactic nuclei [PDF]
It is often held that the X-ray emission from active galactic nuclei (AGN) arises from a region close to the central energy source. Thus X-ray observations may provide the best constraints on the central engine.
Mushotzky, R.
core +1 more source
NAIRAS Version 3 Atmospheric Ionizing Radiation Validation: Comparisons to RaD‐X Measurements
Space Weather, Volume 23, Issue 4, April 2025.Abstract The Nowcast of Aerospace Ionizing RAdiation System (NAIRAS) model predicts dosimetric and radiative flux quantities for assessing human radiation exposure levels and radiation effects on flight electronic systems from the surface of the Earth to deep space. NAIRAS version 3 includes many updates and improvements to the model.
Christopher J. Mertens +2 more
wiley +1 more source
The Astrophysical JournalThe X-ray quasiperiodic oscillation (QPO) is a remarkable form of variability in systems of compact object accretion. RE J1034+396, harboring the most significant X-ray QPO in active galactic nuclei (AGNs), is the most noteworthy source for in-depth ...
Ruisong Xia, Hao Liu, Yongquan Xue
doaj +1 more source
X-ray and infrared diagnostics of nearby active galactic nuclei with MAXI and AKARI [PDF]
, 2016 Nearby active galactic nuclei were diagnosed in the X-ray and mid-to-far infrared wavelengths, with Monitor of All-sky X-ray Image (MAXI) and the Japanese infrared observatory AKARI, respectively. Among the X-ray sources listed in the second release of the MAXI all-sky X-ray source catalog, 100 ones are currently identified as a non-blazar-type active ...
arxiv +1 more source
Meteoritics &Planetary Science, Volume 60, Issue 4, Page 795-822, April 2025.Abstract Impact‐generated hydrothermal systems and postimpact crater lake systems are well‐documented geological phenomena; however, evidence of hydrothermal venting into impact crater lake systems has rarely been reported. We investigated the well‐preserved contact between hydrothermally altered impact melt‐bearing breccia (outer/surficial suevite ...
Matthew J. O. Svensson +4 more
wiley +1 more source
On the Extremely X-Ray Variable Active Galactic Nuclei in the XMM-LSS Field
The Astrophysical JournalWe present a systematic investigation of extremely X-ray variable active galactic nuclei (AGNs) in the ≈5.3 deg ^2 XMM-SERVS XMM-LSS region. Eight variable AGNs are identified with rest-frame 2 keV flux density variability amplitudes around 6–12.
Zijian Zhang +5 more
doaj +1 more source