Related papers: Radio Emission from an Ultraluminous X-Ray Source
Ultraluminous X-ray sources (ULXs) represent the closest and most accessible laboratories to study sustained super-Eddington accretion onto compact objects. Over the past decade, the discoveries of coherent pulsations in a few ULXs has…
Ultraluminous X-ray sources (ULXs) have been described variously as the most luminous normal X-ray binaries, as hypernovae, and as "intermediate-mass" black holes with masses of hundreds to thousands of solar masses. We present results on…
The ultraluminous X-ray sources (ULXs) were isolated in external galaxies for the last 5 years. Their X-ray luminosities exceed 100-10000 times those of brightest Milky Way black hole binaries and they are extremely variable. There are two…
Ultraluminous X-ray sources (ULX) are off-nuclear point sources in nearby galaxies whose X-ray luminosity exceeds the theoretical maximum for spherical infall (the Eddington limit) onto stellar-mass black holes. Their luminosity ranges from…
The nature of the ultra-luminous X-ray sources (ULXs) in the nearby galaxies is a matter of debates. One of the popular hypothesis associates them with accretion at a sub-Eddington rate on to intermediate mass black holes. Another…
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…
We review the likely population, observational properties, and broad implications of stellar-mass black holes and ultraluminous x-ray sources. We focus on the clear empirical rules connecting accretion and outflow that have been established…
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…
We present the results from an X-ray and optical study of a new sample of eight extreme luminosity ultraluminous X-ray source (ULX) candidates, which were selected as the brightest ULXs (with L_X > 5x10^40 erg/s) located within 100 Mpc…
We report the discovery of a new candidate ultraluminous X-ray source (ULX) in the nearby edge-on spiral galaxy NGC 891. The source, which has an absorbed flux of F_X ~ 10^-12 erg/s/cm^2 (corresponding to L_X > 10^40 erg/s at 9 Mpc), must…
Multiwavelength observations may help us understand the physical nature of the ultraluminous X-ray sources (ULXs) found in external galaxies. Enabled by the arcsecond X-ray source positions now available from Chandra, there has been…
The brightest Ultra-Luminous X-ray source HLX-1 in the galaxy ESO 243-49 currently provides strong evidence for the existence of intermediate mass black holes. Here we present the latest multi-wavelength results on this intriguing source in…
Jets are ubiquitous in accreting black holes. Often ignored, they may be a major contributor to the emitted spectral energy distribution for sub-Eddington black holes. For example, recent observations of radio-to-X-ray correlations and…
Evidence is mounting that some Ultra-luminous X-ray sources (ULXs) may contain accreting intermediate-mass black holes (IMBHs). We review the current observational evidence for IMBH-ULXs. While low-luminosity ULXs with L_X <~ 10^39.5 erg/s…
Most ultraluminous X-ray sources (ULXs) display a typical set of properties not seen in Galactic stellar-mass black holes (BHs): higher luminosity Lx > 3 10^39 erg/s, unusually soft X-ray components (kT < 0.3 keV) and a characteristic…
Most galactic nuclei are now believed to harbour supermassive black holes. Studies of stellar motions in the central few light-years of our Milky Way Galaxy indicate the presence of a dark object with a mass of about 2.6 million solar…
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…
The ultra-luminous X-ray source CXO~J133815.6+043255 is a strong candidate for a bona-fide intermediate mass black hole, residing in the outskirts of NGC~5252. We present 22~GHz radio observations of this source obtained serendipitously in…
We report the discovery of a new ultraluminous X-ray source (ULX) associated with a globular cluster in the elliptical galaxy NGC 4649. The X-ray source was initially detected with a luminosity below 5 x 10^38 erg/s, but in subsequent…
Ultraluminous X-ray sources (ULXs) with X-ray luminosities larger than the Eddington luminosity of stellar mass objects may be powered by intermediate mass black holes (IBHs) of masses Mbh~10^3Msun. If IBHs form in young dense stellar…