Results 21 to 30 of about 9,171,233 (161)
A New Sample of Transient Ultraluminous X-Ray Sources Serendipitously Discovered by Swift/XRT
The Astrophysical Journal, 2023 Ultraluminous X-ray sources (ULXs) are our best laboratories for studying extreme super-Eddington accretion. Most studies of these objects are of relatively persistent sources; however, there is growing evidence to suggest a large fraction of these ...
Murray Brightman +13 more
doaj +1 more source
Observations of Ultraluminous X-ray Sources [PDF]
AIP Conference Proceedings, 2010 Review talk given at the meeting Mykonos-2010:"Binary Star Evolution: Mass Loss, Accretion, and Mergers".
Jeanette C. Gladstone +2 more
openaire +2 more sources
Constraint on the Accretion of NGC 6946 X-1 Using Broadband X-Ray Data
The Astrophysical Journal, 2023 We analyze broadband X-ray data of NGC 6946 X-1 and probe plausible accretion scenarios in this ULX. NGC 6946 X-1 is a persistent soft source with broadband continuum spectra described by two thermal disk components. The cool accretion disk temperature T
Tanuman Ghosh, Vikram Rana
doaj +1 more source
The Origin of the Ultraluminous X-Ray Sources [PDF]
The Astrophysical Journal, 2017 Abstract Recently, several ultraluminous X-ray (ULX) sources were shown to host a neutron star (NS) accretor. We perform a suite of evolutionary calculations, which show that, in fact, NSs are the dominant type of ULX accretor. Although black holes (BH) dominate early epochs after the star-formation burst, NSs outweigh them after a few ...
Wiktorowicz, Grzegorz +3 more
openaire +3 more sources
Searching for overlooked TDEs in the 4XMM catalogue
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract Tidal disruption events (TDEs) are usually discovered as bright transients, either in the X‐ray or optical/UV band. These events are often characterized by a “super‐soft” emission in the X‐ray band, which has not been observed in any other extragalactic source, with few exceptions (novae and supersoft active galactic nuclei, AGN), which can ...
Andrea Sacchi +2 more
wiley +1 more source
X-RAY MONITORING OF ULTRALUMINOUS X-RAY SOURCES [PDF]
The Astrophysical Journal, 2009 X-ray monitoring observations were performed with the Swift observatory of the ultraluminous X-ray sources Holmberg IX X-1, NGC 5408 X-1, and NGC 4395 X-2 and also of the nuclear X-ray source in NGC 4395. Holmberg IX X-1 remains in the hard X-ray spectral state as its flux varies by a factor of 7 up to an (isotropic) luminosity of 2.8E40 erg/s.
Kaaret, Philip, Feng, Hua
openaire +2 more sources
The hyperluminous X‐ray source population
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract We have recently published a catalog of 1843 candidate ultraluminous X‐ray sources (ULXs). This is the largest catalog of ULXs to date and was built by cross‐correlating recent serendipitous source catalogs from the XMM‐Newton, Swift, and Chandra observatories with a large sample of galaxies, primarily from HyperLEDA.
A. D. A. MacKenzie +2 more
wiley +1 more source
A Long-Term Study of Ultraluminous X-ray Sources in NGC 891
Universe, 2021 We perform empirical fits to the Chandra and XMM-Newton spectra of three ultraluminous X-ray sources (ULXs) in the edge-on spiral galaxy NGC 891, monitoring the region over a 17-year time window.
Nicholas M. Earley +2 more
doaj +1 more source
NATURE OF THE EXTREME ULTRALUMINOUS X-RAY SOURCES [PDF]
The Astrophysical Journal, 2015 In this proof-of-concept study we demonstrate that in a binary system mass can be transferred toward an accreting compact object at extremely high rate. If the transferred mass is efficiently converted to X-ray luminosity (with disregard of the classical Eddington limit) or if the X-rays are focused into a narrow beam then binaries can form extreme ULX
Wiktorowicz, Grzegorz +3 more
openaire +4 more sources
Ultraluminous X-ray Sources [PDF]
Proceedings of Accretion Processes in Cosmic Sources – II — PoS(APCS2018), 2019 Ultraluminous X-ray sources (ULXs) represent a class of binary systems that are more luminous than any black hole in our Galaxy. The nature of these objects remained unclear for a long time. The most popular models for the ULXs involve either intermediate mass black holes (IMBHs) or stellar-mass black holes accreting at super-Eddington rates.
openaire +2 more sources