Results 21 to 30 of about 5,289 (173)
Wind-powered Ultraluminous X-ray Sources [PDF]
The Astrophysical Journal, 2021 Abstract Although ultraluminous X-ray sources (ULX) are important for astrophysics because of their extreme apparent super-Eddington luminosities, their nature is still poorly known. Theoretical and observational studies suggest that ULXs could be a diversified group of objects that are composed of low-mass X-ray binaries, high-mass X ...
Grzegorz Wiktorowicz +5 more
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Ultraluminous X-Ray Sources [PDF]
Annual Review of Astronomy and Astrophysics, 2017 We review observations of ultraluminous X-ray sources (ULXs). X-ray spectroscopic and timing studies of ULXs suggest a new accretion state distinct from those seen in Galactic stellar-mass black hole binaries. The detection of coherent pulsations indicates the presence of neutron-star accretors in three ULXs and therefore apparently super-Eddington ...
Kaaret, Philip +2 more
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New Astronomy Reviews, 2023 A preprint as close as possible to the open access article at: https://www.sciencedirect.com/science/article/pii/S1387647322000306?via ...
King, A., Lasota, J.-P., Middleton, M.
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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
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Ultrafast outflows in ultraluminous X‐ray sources [PDF]
Astronomische Nachrichten, 2017 Ultraluminous X‐ray sources (ULXs) are bright extragalactic sources with X‐ray luminosities above 1039 erg s−1 powered by accretion onto compact objects. According to the first studies performed with XMM‐Newton, ULXs seemed to be excellent candidates to host intermediate‐mass black holes (102 − 4M⊙).
Pinto, C. +3 more
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Ultraluminous X-ray sources are beamed
Monthly Notices of the Royal Astronomical Society, 2023 ABSTRACT We show that magnetar models for ultraluminous X-ray sources (ULXs) have serious internal inconsistencies. The magnetic fields required to increase the limiting luminosity for radiation pressure above the observed (assumed isotropic) luminosities are completely incompatible with the spin-up rates observed for pulsing ULXs.
Jean–Pierre Lasota, Andrew King
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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.
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Decomposing the Spectrum of Ultraluminous X-Ray Pulsar NGC 300 ULX-1
The Astrophysical Journal, 2023 A phase-resolved analysis on the X-ray spectrum of ultraluminous X-ray pulsar (ULXP) NGC 300 ULX-1 is performed with data taken with XMM-Newton and NuSTAR on 2016 December 16. In addition to the classical phase-restricting analysis, a method developed in
Shogo B. Kobayashi +5 more
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X-ray observations of ultraluminous X-ray sources [PDF]
Astrophysics and Space Science, 2007 Invited talk at the 5th Stromlo Symposium. 10 pages, 4 figures.
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Constraining Soft and Hard X-Ray Irradiation in Ultraluminous X-Ray Sources [PDF]
The Astrophysical Journal, 2021 Abstract Most ultraluminous X-ray sources (ULXs) are argued to be powered by supercritical accretion onto compact objects. One of the key questions regarding these objects is whether or not the hard X-rays are geometrically beamed toward the symmetric axis.
Yanli Qiu, Hua Feng
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