Results 41 to 50 of about 182 (138)

Astronomical Signatures of Dark Matter

Advances in High Energy Physics, Volume 2014, Issue 1, 2014., 2014
Several independent astronomical observations in different wavelength bands reveal the existence of much larger quantities of matter than what we would deduce from assuming a solar mass to light ratio. They are very high velocities of individual galaxies within clusters of galaxies, higher than expected rotation rates of stars in the outer regions of ...
Paul Gorenstein, Wallace Tucker, Anselmo Meregaglia   +2 more
wiley   +1 more source

Hidden No More: Spotlight on Tidal Disruption Events in Active Galactic Nuclei

Astronomische Nachrichten, Volume 347, Issue 5, June 2026.
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

Intermediate Mass Black Holes: Their Motion and Associated Energetics

Advances in High Energy Physics, Volume 2014, Issue 1, 2014., 2014
There is a lot of current astrophysical evidence and interest in intermediate mass black holes (IMBH), ranging from a few hundred to several thousand solar masses. The active galaxy M82 and the globular cluster G1 in M31, for example, are known to host such objects.
C. Sivaram, Kenath Arun, Christian Corda
wiley   +1 more source

Deep Space Network Radio Science and Ground‐Based Planetary Radar in the Next Decade

Radio Science, Volume 60, Issue 7, July 2025.
Abstract The Deep Space Network (DSN) has been a core operational element of NASA's crewed and robotic exploration of the Solar System since the early 1960s. The primary role of the DSN has been to acquire telemetry and navigation data, but over the years, its radiometric and radar capabilities have expanded to form a system for obtaining unique ...
R. S. Park, J. E. Riedel, N. Rodriguez‐Alvarez, M. Brozovic, L. A. M. Benner, P. Vergados, D. Buccino, C. S. Jacobs, L. S. Locke, S. W. Asmar, R. Castano, T. J. W. Lazio, J. Jao, C. Lee   +13 more
wiley   +1 more source

Retrograde versus Prograde Models of Accreting Black Holes

Advances in Astronomy, Volume 2013, Issue 1, 2013., 2013
There is a general consensus that magnetic fields, accretion disks, and rotating black holes are instrumental in the generation of the most powerful sources of energy in the known universe. Nonetheless, because magnetized accretion onto rotating black holes involves both the complications of nonlinear magnetohydrodynamics that currently cannot fully be
David Garofalo, Alberto J. Castro-Tirado
wiley   +1 more source

Fast inflows as the adjacent fuel of supermassive black hole accretion disks in quasars [PDF]

Nature, 2019
Quasars, which are exceptionally bright objects at the centres (or nuclei) of galaxies, are thought to be produced through the accretion of gas into disks surrounding supermassive black holes1-3. There is observational evidence at galactic and circumnuclear scales4 that gas flows inwards towards accretion disks around black holes, and such an inflow ...
Hongyan, Zhou, Xiheng, Shi, Weimin, Yuan, Lei, Hao, Xiangjun, Chen, Jian, Ge, Tuo, Ji, Peng, Jiang, Ge, Li, Bifang, Liu, Guilin, Liu, Wenjuan, Liu, Honglin, Lu, Xiang, Pan, Juntai, Shen, Xinwen, Shu, Luming, Sun, Qiguo, Tian, Huiyuan, Wang, Tinggui, Wang, Shengmiao, Wu, Chenwei, Yang, Shaohua, Zhang, Zhihao, Zhong   +23 more
openaire   +2 more sources

Redshift‐Agnostic Machine Learning Classification: Unveiling Peak Performance in Galaxy, Star, and Quasar Classification (Using SDSS DR17)

Astronomische Nachrichten, Volume 346, Issue 5, June 2025.
ABSTRACT Classification of galaxies, stars, and quasars using spectral data is fundamental to astronomy, but often relies heavily on redshift. This study evaluates the performance of 10 machine learning algorithms on SDSS data to classify these objects, with a particular focus on scenarios where redshift information is unavailable.
Debashis Chatterjee, Prithwish Ghosh
wiley   +1 more source

AGN Triggering in the Infall Regions of Distant X‐Ray Luminous Galaxy Clusters at 0.9 < z≲1.6

Advances in Astronomy, Volume 2012, Issue 1, 2012., 2012
Observational constraints on the average radial distribution profile of AGN in distant galaxy clusters can provide important clues on the triggering mechanisms of AGN activity in dense environments and are essential for a completeness evaluation of cluster selection techniques in the X‐ray and mm wavebands.
R. Fassbender, R. Šuhada, A. Nastasi, Angela Bongiorno   +3 more
wiley   +1 more source

Quasars Can Signpost Supermassive Black Hole Binaries

The Astrophysical Journal
Abstract Supermassive black holes (SMBHs) are found in the centers of massive galaxies, and galaxy mergers should eventually lead to SMBH mergers. Quasar activity has long been associated with galaxy mergers, so here we investigate if supermassive black hole binaries (SMBHBs) are preferentially found in quasars.
J. Andrew Casey-Clyde, Chiara M. F. Mingarelli, Jenny E. Greene, Andy D. Goulding, Siyuan Chen, Jonathan R. Trump   +5 more
openaire   +3 more sources

Probing extreme black‐hole outflows on short timescales via high spectral‐resolution x‐ray imagers

Astronomische Nachrichten, Volume 345, Issue 6-7, July-August 2024.
Abstract We investigate outflows and the physics of super‐Eddington versus sub‐Eddington regimes in black hole systems. Our focus is on prospective science using next‐generation high‐resolution soft x‐ray instruments. We highlight the properties of black hole ultraluminous x‐ray source (ULX) systems in particular. Owing to scale invariance in accreting
C. Pinto, J. F. Steiner, A. Bodaghee, P. Chakraborty, M. Sobolewska, D. R. Pasham, A. Ogorzalek, J. Zuhone, A. Bogdan, M. Vogelsberger   +9 more
wiley   +1 more source