Related papers: Ultraluminous X-ray sources
In our recent work, we demonstrated that a novel X-ray scaling method, originally introduced for Galactic black holes, could be reliably extended to estimate the mass of supermassive black holes accreting at moderate to high level. Here, we…
Using Chandra observations we have identified a sample of seven off-nuclear X-ray sources, in the redshift range z=0.072-0.283, located within optically bright galaxies in the COSMOS Survey. Using the multi-wavelength coverage available in…
We analyse all the available Chandra observations of the Cartwheel Galaxy and its compact group, taken between 2001 and 2008, with the main aim of addressing the variability in the X-ray band for this spectacular collisional ring galaxy. We…
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…
Ultraluminous X-ray sources (ULXs) are bright X-ray sources in nearby galaxies not associated with the central supermassive black hole. Their luminosities imply they are powered by either an extreme accretion rate onto a compact stellar…
Ultra-Luminous X-ray sources (ULX) are X-ray binaries with Lx>1E^39 ergs/s. The most spectacular examples of ULX occur in starburst galaxies and are now understood to be young, luminous High Mass X-ray Binaries. The conditions under which…
Here we present the results of panoramic and long-slit observations of eight ULX nebular counterparts held with the 6m SAO telescope. In two ULXNe we detected for the first time signatures of high excitation ([OIII]5007 / H\beta > 5). Two…
Recent X-ray observations have had a major impact on topics ranging from protostars to cosmology. They have also drawn attention to important and general physical processes that currently limit our understanding of thermal and nonthermal…
Employing hybrid population synthesis, a model of the population of ultraluminous X-ray sources (ULX) in the binary systems with a black hole (BH) accretors is computed. It is compared to the model of the population of ULX with magnetized…
We present the first results of an XMM-Newton EPIC observation of the luminous X-ray source population in the supergiant spiral galaxy M101. We have studied the properties of the fourteen most luminous sources, all of which have intrinsic…
Observations of high-redshift quasars frequently promote suggestions of large black hole masses, whose presence so early in cosmic time is not easily explicable. I consider the parallel with ultraluminous X-ray sources (ULXs) -- now known…
We report the serendipitous discovery of several unresolved X-ray sources lying in the prominent spiral arms of the galaxy KUG 0214-057 in XMM-Newton observations. The location of these X-ray sources strongly suggests that at least three,…
We present the results of a radio monitoring campaign to search for radio emission from nearby ultra-luminous X-ray sources (ULXs). These sources are bright off-nuclear X-ray point sources with luminosities exceeding L_X > 10^39 erg/sec. A…
Context. ULXs ($L_\textrm{X}>10^{39}$ erg s$^{-1}$) are excellent probes of accretion physics, star formation and IMBHs searches. As the sample size of X-ray data from modern observatories increases, producing extensive catalogues of ULXs…
We present a new analysis of X-ray spectra of the archetypal ultraluminous X-ray source (ULX) Holmberg IX X-1 obtained by the Swift, XMM-Newton and NuSTAR observatories. This ULX is a persistent source, with a typical luminosity of ~10^40…
Following a serendipitous detection with the NuSTAR observatory, we present a multi-epoch spectral and temporal analysis of an extreme ultraluminous X-ray source (ULX) located in the outskirts of the Circinus galaxy, hereafter Circinus…
X-ray data provide insights into accretion processes and the compact objects of ultraluminous X-ray sources (ULXs), while optical and infrared (IR) observations help identify the donor star and surrounding environment. Together, these…
It was recently proposed that a significant fraction of ultraluminous X-ray sources (ULXs) actually host a neutron star (NS) accretor. We have performed a systematic study on the NS ULX population in Milky Way-like galaxies, by combining…
The black hole mass and accretion rate in Ultraluminous X-ray sources (ULXs) in external galaxies, whose X-ray luminosities exceed those of the brightest black holes in our Galaxy by hundreds and thousands of times$^{1,2}$, is an unsolved…
Ultra-luminous X-ray sources (ULXs) are X-ray bright (L$_{\rm X-ray} >$3$\times$10$^{39}$erg s$^{-1}$) extra-galactic objects that are powered by either neutron stars, or stellar or intermediate-mass black holes (IMBHs) but few have been…