Related papers: The sub-classes of ultraluminous X-ray sources
We derive the luminosity-temperature relation for the super-critically accreting black holes (BHs) and compare it to the data on ultraluminous X-ray sources (ULXs). At super-Eddington accretion rates, an outflow forms within the…
Ultraluminous X-ray sources (ULXs) are non-nuclear point-like objects observed with extremely high X-ray luminosity that exceeds the Eddington limit of a $\rm10\,M_\odot$ black hole. A fraction of ULXs has been confirmed to contain neutron…
Ultraluminous X-ray sources (ULXs) are some of the brightest phenomena found outside of a galaxy's nucleus, and their explanation typically invokes accretion of material onto a black hole. Here, we perform the largest population study to…
The number of Ultraluminous X-ray Sources (ULXs) is observed to be correlated with the current star formation rate in late-type galaxies and with the stellar mass in early-type galaxies (ETGs). Since there is very little gas, dust or star…
I suggest that the beaming factor in bright ULXs varies as $b \propto \dot m^{-2}$, where $\dot m$ is the Eddington ratio for accretion. This is required by the observed universal $L_{\rm soft} \propto T^{-4}$ relation between soft--excess…
Ultraluminous X-ray sources (ULXs) are extragalactic X-ray emitters located off-center of their host galaxy and with a luminosity in excess of a few ${10^{39}\text{ erg s}^{-1}}$, if emitted isotropically. The discovery of periodic…
We assess the claim that Ultra-luminous X-ray sources (ULXs) host intermediate-mass black holes (BH) by comparing the cool disc-blackbody model with a range of other models, namelly a more complex physical model based on a power-law…
The ultraluminous X-ray source (ULX) population is known to contain neutron stars, but the relative number of these compared to black hole primaries is unknown. Assuming classical super-critical accretion and resultant geometrical beaming,…
Chandra observations of the Cartwheel galaxy reveal a population of ultraluminous X-ray sources (ULXs) with lifetimes < 10^7 yr associated with a spreading wave of star formation which began some 3 x 10^8 yr ago. A population of high-mass…
We model the multiwavelength properties of binaries accreting at super-critical rates with the aim to better understand the observational properties of Ultra-luminous X-ray Sources (ULXs). We calculate an extended grid of binary systems…
With the discovery of pulsations in some of the ultra-luminous X-ray sources (ULXs), it is quite clear that most of the ULXs harbor either a neutron star or a stellar mass black hole as a compact object accreting at super-Eddington rates.…
Hard X-ray observations are the most efficient way to discriminate accretion-powered sources from star-light. Furthermore, hard X-rays are less affected than other bands by obscuration. For these reasons the advent of imaging instruments…
We have identified three ultraluminous X-ray sources (ULXs) hosted by globular clusters (GCs) within NGC 1316's stellar system. These discoveries bring the total number of known ULXs in GCs up to 20. We find that the X-ray spectra of the…
Gravitational waves from the binary black hole (BH) merger GW150914 may enlighten our understanding of ultra-luminous X-ray sources (ULXs), as BHs>30Msun can reach luminosities>4x10^39 erg s^-1 without exceeding their Eddington limit. It is…
We present a new, multi-mission catalogue of ultraluminous X-ray source (ULX) candidates, based on recent data releases from each of the XMM-Newton, Swift and Chandra observatories (the 4XMM-DR10, 2SXPS and CSC2 catalogues, respectively).…
Current stellar evolution models predict that during the core collapse of massive stars, a considerable amount of the stellar material will fall back onto the compact, collapsed remnants (neutron stars or black holes), usually in the form…
Recent Chandra and XMM-Newton surveys have confirmed that the cosmic X-ray background is mostly due to accretion onto super-massive black holes, integrated over cosmic time. Here we review the results obtained from the photometric and…
Ultraluminous x-ray sources (ULXs) in nearby galaxies shine brighter than any X-ray source in our Galaxy. ULXs are usually modeled as stellar-mass black holes (BHs) accreting at very high rates or intermediate-mass BHs. We present…
Ultraluminous X-ray sources are non-nuclear point sources exceeding the Eddington luminosity of a 10 Solar mass black hole. Modern consensus for a majority of the ULX population is that they are powered by stellar-mass black holes or…
We report the Chandra/ACIS-S detection of more than 20 ultraluminous X-ray sources (ULXs, L_{0.5-10 keV} >~ 3 x 10^{39} ergs/sec) in the Cartwheel collisional ring galaxy system, of which over a dozen are located in the outer active…