Spectral variability of ultraluminous X-ray sources

Kajava, J. J. E.; Poutanen, Juri

doi:10.1063/1.3002507

Cited by 3 publications

(3 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By inspecting the behaviour of disc temperature against the unabsorbed luminosity we can see that the emission does not adhere to the L∝ T 4 relation seen in BHXRBs at sub-Eddington rates 9 but appears to invert or flatten at the highest luminosities (in XMM(3-4); see Supplementary Figure 2). This trend has been seen in the X-ray spectra of both ULXs 47,48 and in the very high state of some stellar-mass black hole X-ray binaries 49 , thus supporting our identification of the source.…”

Section: Supplementary Information Researchsupporting

confidence: 86%

See 1 more Smart Citation

Bright radio emission from an ultraluminous stellar-mass microquasar in M 31

Middleton

Miller-Jones

Markoff

et al. 2012

Nature

119

125

View full text Add to dashboard Cite

A subset of ultraluminous X-ray sources (those with luminosities of less than 10(40) erg s(-1); ref. 1) are thought to be powered by the accretion of gas onto black holes with masses of ∼5-20M cicled dot, probably by means of an accretion disk. The X-ray and radio emission are coupled in such Galactic sources; the radio emission originates in a relativistic jet thought to be launched from the innermost regions near the black hole, with the most powerful emission occurring when the rate of infalling matter approaches a theoretical maximum (the Eddington limit). Only four such maximal sources are known in the Milky Way, and the absorption of soft X-rays in the interstellar medium hinders the determination of the causal sequence of events that leads to the ejection of the jet. Here we report radio and X-ray observations of a bright new X-ray source in the nearby galaxy M 31, whose peak luminosity exceeded 10(39) erg s(-1). The radio luminosity is extremely high and shows variability on a timescale of tens of minutes, arguing that the source is highly compact and powered by accretion close to the Eddington limit onto a black hole of stellar mass. Continued radio and X-ray monitoring of such sources should reveal the causal relationship between the accretion flow and the powerful jet emission.

show abstract

Section: Supplementary Information Researchsupporting

confidence: 86%

“…and XRT (1-5). The increase in temperature between the highest luminosity spectrum and the disc dominated spectrum on the decay appears to match the behaviour seen in other low luminosity ULXs 47,48 and in the very high state of some stellar-mass black hole X-ray binaries 49 , and is in contrast to that observed in sub-Eddington BHXRBs.…”

Section: Supplementarysupporting

confidence: 77%

Bright radio emission from an ultraluminous stellar-mass microquasar in M 31

Middleton

Miller-Jones

Markoff

et al. 2012

Nature

119

125

View full text Add to dashboard Cite

show abstract

“…Interesting trends have been reported recently. Some ULXs (such as HoIX X-1) show spectral softening when the photon luminosity increases (Kajava & Poutanen. 2008).…”

Section: Introductionmentioning

confidence: 99%

New Spectral State of Supercritical Accretion Flow with Comptonizing Outflow

Kawashima

Ohsuga

Mineshige

et al. 2009

Publications of the Astronomical Society of Japan

View full text Add to dashboard Cite

Supercritical accretion flows inevitably produce radiation-pressure driven outflows, which will Compton up-scatter soft photons from the underlying accretion flow, thereby making hard emission. We perform two dimensional radiation hydrodynamic simulations of supercritical accretion flows and outflows, incorporating such Compton scattering effects, and demonstrate that there appears a new hard spectral state at higher photon luminosities than that of the slim-disk state. In this state, as the photon luminosity increases, the photon index decreases and the fraction of the hard emission increases. The Compton y-parameter is of the order of unity (and thus the photon index will be ∼ 2) when the apparent photon luminosity is ∼30L E (with L E being the Eddington luminosity) for nearly face-on sources. This explains the observed spectral hardening of the ULX NGC1313 X-2 in its brightening phase and thus supports the model of supercritical accretion onto stellar mass black holes in this ULX.

show abstract

Spectral States and Evolution of Ultraluminous X-Ray Sources

Feng

Kaaret

2009

ApJ

View full text Add to dashboard Cite

We examined spectral evolution in ultraluminous X-ray sources (ULXs) with apparent luminosities of about 10 40 ergs s −1 . Based on new results in this paper and those reported in the literature, two common spectral behaviors were found. Some ULXs in starburst galaxies have varying luminosity (L) but remain in the hard state with power-law spectra and a constant, hard photon index (Γ). Other ULXs, such as NGC 5204 X-1, show a correlation between L and Γ. We interpret this L − Γ correlated phase as an intermediate state with hybrid properties from the thermal dominant and steep power-law states. When the spectra of NGC 5204 X-1 are fitted with a multicolor disk blackbody plus powerlaw model, the X-ray luminosity increases with the effective temperature of the accretion disk in a manner similar to that found in stellar-mass black hole X-ray binaries, suggesting that the emission arises from an accretion disk. The luminosity, disk size, and temperature suggest that NGC 5204 X-1 harbors a compact object more massive than stellar-mass black holes. In contrast, the disk model in IC 342 X-1 is ruled out because the luminosity decreases as the temperature increases; sources with such behaviors may represent a class of objects with super-Eddington accretion. Also, we report a peculiar soft spectral feature from IC 342 X-2 and variability on a time scale of 20 ks from Holmberg II X-1. More observations are needed to test these results. Subject headings: black hole physics -accretion, accretion disks -X-rays: binaries -X-rays: individual (NGC 5204 X-1, Holmberg II X-1, IC 342 X-1 and X-2, the Antennae X-11, X-16, X-42, and X-44, NGC 1313 X-1 and X-2, M82 X41.4+60 and X42.3+59) 4

show abstract

Spectral variability of ultraluminous X-ray sources

Cited by 3 publications

References 43 publications

Bright radio emission from an ultraluminous stellar-mass microquasar in M 31

Bright radio emission from an ultraluminous stellar-mass microquasar in M 31

New Spectral State of Supercritical Accretion Flow with Comptonizing Outflow

Spectral States and Evolution of Ultraluminous X-Ray Sources

Contact Info

Product

Resources

About