Related papers: Ultraluminous X-ray sources
Ultraluminous X-ray sources (ULXs), first observed ~30 years ago, have been argued as extreme stellar mass black hole binaries or a new class intermediate mass black hole. In order to settle this debate, scientists have utilised a wide…
We review the available estimates of the masses of the compact object in Ultraluminous X-ray Sources (ULXs) and critically reconsider the stellar-mass versus intermediate-mass black hole interpretations. Black holes of several hundreds to…
I suggest that there are two classes of ultraluminous X-ray sources (ULXs), corresponding to super-Eddington mass inflow in two situations: (a) thermal-timescale mass transfer in high-mass X-ray binaries, and (b) long-lasting transient…
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…
We suggest that the ultraluminous X-ray sources located in external galaxies (ULXs) are supercritical accretion disks like that in SS433, observed close to the disk axis. We estimate parameters of the SS433 funnel, where the relativistic…
Ultraluminous X-ray sources (ULXs) with 10^39 < L_x < 10^41 erg/s have been discovered in great numbers in external galaxies with ROSAT, Chandra, and XMM-Newton. The central question regarding this important class of sources is whether they…
Ultra-Luminous X-ray sources (ULXs) are accreting black holes for which their X-ray properties have been seen to be different to the case of stellar-mass black hole binaries. For most of the cases their intrinsic energy spectra are well…
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…
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…
The study of ultraluminous X-ray sources (ULXs) has changed dramatically over the last decade. In this review we first describe the most important observations of ULXs in various wavebands, and across multiple scales in space and time. We…
Supercritical accretion onto compact objects may drive massive winds that are nearly spherical, optically thick, and Eddington limited. Blackbody emission from the photosphere is the direct observational signature of the wind. Here we…
Ultraluminous X-ray sources (ULXs) are likely to include different physical types of objects. We discuss some possible subclasses, reviewing the properties of a sample of ULXs recently observed by Chandra and XMM-Newton. Sources with an…
We show that ultraluminous X-ray sources (ULXs) with coherent X-ray pulsing (PULXs) probably have neutron-star spin axes significantly misaligned from their central accretion discs. Scattering in the funnels collimating their emission and…
Ultraluminous X-ray sources (ULXs) have captivated researchers for decades due to their exceptionally high luminosities and unique spectral characteristics. Some of these sources defy expectations by exhibiting super-Eddington luminosities…
Most ultraluminous X-ray sources (ULXs) are thought to be supercritical accreting compact objects, where massive outflows are inevitable. Using the long-term monitoring data with the Swift X-ray Telescope, we identified a common feature in…
Ultraluminous X-ray sources (ULXs) with Lx > 10^{39} ergs/s have been discovered in great numbers in external galaxies with ROSAT, Chandra, and XMM. The central question regarding this important class of sources is whether they represent an…
Constraining the astrophysical nature of Ultra-Luminous X-ray (ULX) sources, which have X-ray luminosities exceeding 10^39 erg/s, has been elusive due to the optical faintness of any counterparts. With high spectral resolution observations…
Most ultraluminous X-ray sources (ULXs) are thought to be powered by neutron stars and black holes accreting beyond the Eddington limit. If the compact object is a black hole or a neutron star with a magnetic field $\lesssim10^{12}$ G, the…
Ultraluminous X-ray sources (ULXs) are mainly powered by accretion in neutron stars or stellar-mass black holes. Accreting at rates exceeding the Eddington limit by factors of a few up to hundreds, radiation pressure is expected to inflate…
The luminosity range at and just below the 10^39 erg/s cut-off for defining ultraluminous X-ray sources (ULXs) is a little-explored regime. It none-the-less hosts a large number of X-ray sources, and has great potential for improving our…