Results 1 to 10 of about 5,289 (173)

Synchrotron Cutoff in Ultraluminous X-Ray Sources

The Astrophysical Journal, 2023
The origin of spectral curvature at energies E ≃ 10 keV in ultraluminous X-ray sources (ULXs) is not well understood. In this paper, we propose a novel mechanism based on synchrotron radiation to explain this cutoff.
Tanuman Ghosh, Shiv Sethi, Vikram Rana
doaj   +3 more sources

Winds in ultraluminous X‐ray sources: New challenges

Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023
Abstract Ultraluminous X‐ray sources (ULXs) are extreme X‐ray binaries shining above 1039 erg/s, in most cases as a consequence of super‐Eddington accretion onto neutron stars and stellar‐mass black holes accreting above their Eddington limit. This was understood after the discovery of coherent pulsations, cyclotron lines, and powerful winds.
C. Pinto, P. Kosec
wiley   +3 more sources

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, Jean-Marie Hameury, Jean-Pierre Lasota, Ranieri D. Baldi, Gabriele Bruni, Jenna M. Cann, Hannah Earnshaw, Felix Fürst, Marianne Heida, Amruta Jaodand, Margaret Lazzarini, Matthew J. Middleton, Dominic J. Walton, Kimberly A. Weaver   +13 more
doaj   +1 more source

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

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, Guido Risaliti, Giovanni Miniutti   +2 more
wiley   +1 more source

The high energy X-ray probe (HEX-P): studying extreme accretion with ultraluminous X-ray sources

Frontiers in Astronomy and Space Sciences, 2023
Introduction: Ultraluminous X-ray sources (ULXs) represent an extreme class of accreting compact objects: from the identification of some of the accretors as neutron stars to the detection of powerful winds travelling at 0.1–0.2 c, the increasing ...
Matteo Bachetti, Matthew J. Middleton, Ciro Pinto, Andrés Gúrpide, Dominic J. Walton, Murray Brightman, Bret Lehmer, Timothy P. Roberts, Georgios Vasilopoulos, Jason Alford, Roberta Amato, Elena Ambrosi, Lixin Dai, Hannah P. Earnshaw, Hamza El Byad, Javier A. García, Javier A. García, Gian Luca Israel, Amruta Jaodand, Kristin Madsen, Chandreyee Maitra, Shifra Mandel, Kaya Mori, Fabio Pintore, Ken Ohsuga, Maura Pilia, Daniel Stern, George Younes, Anna Wolter   +28 more
doaj   +1 more source

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, T. P. Roberts, D. J. Walton   +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 , Vikram V. Dwarkadas , Victoria Cirillo    +2 more
doaj   +1 more source

The two Ultraluminous X-ray sources in the galaxy NGC 925 [PDF]

, 2018
NGC 925 ULX-1 and ULX-2 are two ultraluminous X-ray sources in the galaxy NGC 925, at a distance of 8.5 Mpc. For the first time, we analyzed high quality, simultaneous XMM-Newton and NuSTAR data of both sources. Although at a first glance ULX-1 resembles
Esposito, P., Israel, G. L., Mereghetti, S., Ochner, P., Paiano, S., Pintore, F., Rodríguez, G., Trinchieri, G., Wolter, A., Zampieri, L.   +9 more
core   +14 more sources

Bubble in the Whale: Identifying the Optical Counterparts and Extended Nebula for the Ultraluminous X-Ray Sources in NGC 4631

The Astrophysical Journal, 2023
We present a deep optical imaging campaign on the starburst galaxy NGC 4631 with CFHT/MegaCam. By supplementing the HST/ACS and Chandra/ACIS archival data, we search for the optical counterpart candidates of the five brightest X-ray sources in this ...
Jing Guo, Jianfeng Wu, Hua Feng, Zheng Cai, Ping Zhou, Changxing Zhou, Shiwu Zhang, Junfeng Wang, Mouyuan Sun, Wei-Min Gu, Shan-Shan Weng, Jifeng Liu   +11 more
doaj   +1 more source