Discovery of Spectral Transitions from Two Ultraluminous Compact X-Ray Sources in IC 342

Kubota, Aya; Mizuno, T.; Makishima, Kazuo; Fukazawa, Yasushi; Kotoku, J.; Ohnishi, T.; Tashiro, M.

doi:10.1086/318903

Cited by 114 publications

(139 citation statements)

References 29 publications

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“…Spectral transitions, similar to those seen in Galactic black hole systems, have been reported in NGC 1313 X-1 (Colbert & Mushotzky 1999) and two sources in IC 342 (Kubota et al 2001). Analysis of XMM-Newton data revealed the presence of a cool accretion disk component (kT in $ 0:1Y0:5 keV) in NGC 1313 X-1, X-2 (Miller et al 2003), and M81 X-9 , which suggested that these sources harbor IMBHs.…”

supporting

confidence: 74%

Accretion Disk Spectra of the Brightest Ultraluminous X‐Ray Source in M82

Yuan

Taam

Misra

et al. 2007

ApJ

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Emission spectra of hot accretion disks characteristic of advection-dominated accretion flow (ADAF) models are investigated for comparison with the brightest ultraluminous source, X-1, in the galaxy M82. If the spectral state of the source is similar to the low-luminosity hard state of stellar mass black holes in our Galaxy, a fit to the Chandra X-ray spectrum and constraints from the radio and infrared upper limits requires a black hole mass in the range of 9 ; 10 4 Y5 ; 10 5 M . Lower black hole masses (P10 4 M ) are possible if M82 X-1 corresponds to the highluminosity hard state of Galactic black hole X-ray binary sources. Both of these spectrally degenerate hot accretion disk solutions lead to an intermediate-mass black hole interpretation for M82 X-1. Since these solutions have different spectral variability with X-ray luminosity and predict different radio/infrared emission, they could be distinguished by future off-axis Chandra observations or simultaneous sensitive radio/infrared detections.

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supporting

confidence: 74%

Accretion Disk Spectra of the Brightest Ultraluminous X‐Ray Source in M82

Yuan

Taam

Misra

et al. 2007

ApJ

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“…This revealed some of them to be well-fitted by the multi-colour disc blackbody model, that describes the optically-thick thermal X-ray emission of an accretion disc around a black hole (Makishima et al 2000). Additionally, multi-epoch observations of some ULXs saw them apparently transiting between spectral states described by either the multi-colour disc blackbody model or a power-law, similar to the transition between low-and high-states seen in Galactic black hole X-ray binaries (Kubota et al 2001). This gave the first strong corroborating evidence -on top of their extraordinary luminosities -that most ULXs are accreting black holes.…”

mentioning

confidence: 73%

X-ray observations of ultraluminous X-ray sources

Roberts

2007

Astrophys Space Sci

179

187

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Ultraluminous X-ray sources (ULXs) are amongst the most intriguing of X-ray source classes. Their extreme luminosities -greater than 10 39 erg s −1 in the 0.3 -10 keV band alone -suggest either the presence of black holes larger than those regularly encountered in our own Galaxy (the Galactic centre excepted), or sources apparently radiating well above the Eddington limit. We review the insights afforded us by studies of their X-ray emission, focussing on what this reveals about the underlying compact object. In particular, we discuss recent deep observations of ULXs by the XMMNewton observatory, and how the unprecedented data quality provided by this mission is starting to discriminate between the different physical models for these extraordinary X-ray emitters.

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“…State transitions following the canonical high/soft versus hard pattern have been reported for two ULXs in IC 342 (Kubota et al 2001) and Holmberg IX X-1 (La Parola et al 2001). However, the temporal coverage for IC 342 was poor, only two observations, while the coverage for Holmberg IX X-1 was poor and had to be stitched together from several different observatories.…”

Section: Fabbiano and White 2006) Many Ulxs Show Strong Variabilitymentioning

confidence: 91%

Spectral State Transitions of the Ultraluminous X-Ray Sources X-1 and X-2 in NGC 1313

Feng

Kaaret

2006

ApJ

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X-ray spectral state transitions are a key signature of black hole X-ray binaries and follow a well-defined pattern. We examined 12 XMM-Newton observations of the nearby spiral galaxy NGC 1313, which harbors two compact ultraluminous X-ray sources (ULXs), X-1 and X-2, in order to determine if the state transitions in ULXs follow the same pattern. For both sources, the spectra were adequately fitted by an absorbed power law with the addition of a low-temperature ( keV) disk blackbody component required in six of the 12 obserkT p 0.1-0.3 vations. As the X-ray luminosity of X-1 increases to a maximum at ergs s Ϫ1 , the power-law photon 40 3 # 10 index softens to 2.5-3.0. This behavior is similar to the canonical spectral state transitions in Galactic black hole binaries, but the source never enters the high/soft or thermal-dominant state and instead enters the steep powerlaw state at high luminosities. X-2 has the opposite behavior and appears to be in the hard state, with a photon index of at high luminosity, but can soften to at the lower luminosities. G p 1.7-2.0 G p 2.5

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Discovery of Spectral Transitions from Two Ultraluminous Compact X-Ray Sources in IC 342

Cited by 114 publications

References 29 publications

Accretion Disk Spectra of the Brightest Ultraluminous X‐Ray Source in M82

Accretion Disk Spectra of the Brightest Ultraluminous X‐Ray Source in M82

X-ray observations of ultraluminous X-ray sources

Spectral State Transitions of the Ultraluminous X-Ray Sources X-1 and X-2 in NGC 1313

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