Related papers: A new Ultraluminous X-ray source in the galaxy NGC…
We present the optical and X-ray study of the ultraluminous X-ray source (ULX) NGC 5474 X-1. The X-ray spectrum taken during the bright state of the source ($L_X \sim 2\times10^{40}$ egs/s) shows signatures of a broad absorption line at…
We present the result of the Chandra high-resolution observation of the Seyfert~2 galaxy NGC 7590. This object was reported to show no X-ray absorption in the low-spatial resolution ASCA data. The XMM observations show that the X-ray…
We present a comprehensive study of the total X-ray emission from the colliding galaxy pair NGC2207/IC2163, based on Chandra, Spitzer, and GALEX data. We detect 28 ultra-luminous X-ray sources (ULXs), 7 of which were not detected previously…
NGC 247 is a nearby late-type bulgeless spiral galaxy that contains an inactive nucleus. We report a serendipitous discovery of an X-ray flare from the galaxy center with a luminosity up to 2*10^39 erg/s in the 0.3-10 keV band with…
We have re-examined the most luminous X-ray sources in the starburst galaxy NGC 4631, using XMM-Newton, Chandra and ROSAT data. The most interesting source is a highly variable supersoft ULX. We suggest that its bolometric luminosity ~ a…
Aims. We analyzed multi-epoch X-ray data of the Ultraluminous X-ray source (ULX) NGC 5055 X-1, with luminosity up to $2.32\times10^{40}\ \rm erg\ s^{-1}$, in order to constrain the physical parameters of the source. Methods. We performed…
The purpose of this study is to find transient X-ray sources in M31, and to investigate and classify their nature. Three X-ray transients were observed with Swift. For each of the three X-ray transients we use the Swift X-ray and optical…
We seek clarification of the nature of X-ray sources detected in M 31. Here we focus on CXOM31 J004253.1+411422, the brightness of which suggests that it belongs to the class of ultraluminous X-ray sources. We determine the X-ray properties…
We report on the discovery of an absorption line at $E=8.56^{+0.05}_{-0.11}$ keV detected with a significance of $>3.3\sigma$ in the NuSTAR and XMM-Newton spectra of a newly discovered hyperluminous X-ray source (HLX, $L_{\rm X}>10^{41}$…
We report the discovery of a ultraluminous X-ray source (ULX; CXO J133815.6+043255) in NGC 5252. This ULX is an off-nuclear point-source, which is 22$^{\prime\prime}$ away from the center of NGC 5252, and has an X-ray luminosity of 1.5…
The advanced capabilities of the Chandra and XMM-Newton observatories mean that, for the first time, the detailed study of the brightest point-like X-ray sources in nearby galaxies outside of the local group is a realistic aim. Here, we…
After nearly a decade in quiescence, the accreting millisecond pulsar IGR J17511$-$3057 displayed a new outburst on 2025 February 11, its third since discovery, following previous activity in 2009 and 2015. We report on an XMM-Newton Target…
(Abridged) We present results based on XMM-Newton observation of the nearby spiral galaxy M51 (NGC5194 and NGC5195). Two ULXs in NGC5194 show evidence for short-term variability, and all but two ULXs vary on long time scales (over a…
Motivated by the recent discoveries that six Ultraluminous X-ray Sources (ULXs) are powered by highly super-Eddington X-ray pulsars, we searched for additional pulsating ULX (PULX) candidates by identifying sources that exhibit long-term…
We have discovered an ultrasoft X-ray transient source, 2XMMi J184725.1-631724, which was detected serendipitously in two XMM-Newton observations in the direction of the center of the galaxy IC 4765-f01-1504 at a redshift of 0.0353. These…
We present the results of Chandra observations of off-nuclear X-ray sources in the spiral galaxy M51 (NGC 5194). 113 X-ray sources have been detected in the field of view and 84 among them project within the disk of NGC 5194. Six and twenty…
We present the results of the first broadband X-ray analysis of the ultraluminous X-ray source NGC 5055 ULX X-1, combining simultaneous data from XMM$-$Newton and NuSTAR missions, with a combined exposure time of $\sim$100 ks across the…
The Cartwheel is one of the most outstanding examples of a dynamically perturbed galaxy where star formation is occurring inside the ring--like structure. In previous studies with Chandra, we detected 16 Ultra Luminous X-ray sources lying…
This paper presents a comprehensive X-ray and multi-wavelength study of ultraluminous X-ray sources (ULXs) in NGC 1566 using archival Chandra, Swift/XRT, James Webb Space Telescope, JWST, and Hubble Space Telescope, HST observations. The…
The extreme extragalactic sources known as Ultraluminous X-ray Sources (ULX) represent a unique testing environment for compact objects population studies and the accretion process. Their nature has long been disputed. Their luminosity,…