Ultraluminous X-Ray Sources

Kaaret, Philip; Feng, Hua; Roberts, T. P.

doi:10.1146/annurev-astro-091916-055259

Cited by 532 publications

(452 citation statements)

References 237 publications

(297 reference statements)

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“…In these models, Lorentz invariance is expected to be broken at very high energies close to the Planck scale, and the speed of light is dependent on the energy of the associated photon [5]. Although many astrophysical sources such as AGNs [6,7], pulsars [8] etc. have been used to search for LIV-induced light speed variation, most of these searches have been done with Gamma-Ray Bursts (GRBs)(See [9][10][11][12][13][14][15][16] and references therein).…”

Section: Introductionmentioning

confidence: 99%

Statistical significance of spectral lag transition in GRB 160625B

Ganguly

Desai

2017

Astroparticle Physics

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Recently Wei et al [1] have found evidence for a transition from positive time lags to negative time lags in the spectral lag data of GRB 160625B. They have fit these observed lags to a sum of two components: an assumed functional form for intrinsic time lag due to astrophysical mechanisms and an energy-dependent speed of light due to quadratic and linear Lorentz invariance violation (LIV) models. Here, we examine the statistical significance of the evidence for a transition to negative time lags. Such a transition, even if present in GRB 160625B, cannot be due to an energy dependent speed of light as this would contradict previous limits by some 3-4 orders of magnitude, and must therefore be of intrinsic astrophysical origin. We use three different model comparison techniques: a frequentist test and two information based criteria (AIC and BIC). From the frequentist model comparison test, we find that the evidence for transition in the spectral lag data is favored at 3.05σ and 3.74σ for the linear and quadratic models respectively. We find that ∆AIC and ∆BIC have values 10 for the spectral lag transition that was motivated as being due to quadratic Lorentz invariance violating model pointing to "decisive evidence". We note however that none of the three models (including the model of intrinsic astrophysical emission) provide a good fit to the data.

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Section: Introductionmentioning

confidence: 99%

Statistical significance of spectral lag transition in GRB 160625B

Ganguly

Desai

2017

Astroparticle Physics

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“…ULXs were initially thought to be powered by intermediate-mass black holes (M BH ∼ 100 − 1000 M ). However, it is now known that the majority of these objects are otherwise normal X-ray binaries with stellar-mass compact objects accreting at super-Eddington rates or with non-isotropic emission geometries [29]. Models and simulations of super-Eddington accretion around black holes [30][31][32] predict a geometrically and optically thick accretion disk around the compact object, with an optically thin, evacuated funnel forming along the object's axis of rotation.…”

Section: The Ultraluminous X-ray Sourcementioning

confidence: 99%

From SN 2010da to NGC 300 ULX-1: Ten Years of Observations of an Unusual High Mass X-Ray Binary in NGC 300

et al. 2020

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In 2010 May, an intermediate luminosity optical transient was discovered in the nearby galaxy NGC 300 by a South African amateur astronomer. In the decade since its discovery, multi-wavelength observations of the misnamed "SN 2010da" have continually re-shaped our understanding of this high mass X-ray binary system. In this review, we present an overview of the multi-wavelength observations and attempts to understand the 2010 transient event and, later, the re-classification of this system as NGC 300 ULX-1: a red supergiant + neutron star ultraluminous X-ray source.On 2010 May 24, the amateur astronomer L. A. G. Monard of Pretoria, South Africa, reported the discovery of an optical transient in the nearby spiral galaxy NGC 300, shown in Figure 1 [1]. The event was given the supernova (SN) designation SN 2010da. The apparent V-band magnitude from the discovery images (16.0±0.2 mag), however, immediately presented a contradiction: at the distance of the host galaxy (2 Mpc [2]), the implied absolute magnitude (M V ∼ −10.5 at maximum; [3]) was too low to be consistent with a true SN explosion. Follow-up spectroscopy confirmed that the transient event was not a genuine SN, and instead resembled a luminous blue variable (LBV)-like outburst from a dust-enshrouded massive star [4,5]. Multi-color imaging of the outburst was obtained with the SMARTS 1.3m telescope at Cerro Tololo ∼2 days after the initial discovery [6] and ∼3 weeks post-outburst [7]. SN 2010da thus joined the heterogeneous group of objects known as "supernova impostors," which are frequently interpreted as massive stars experiencing non-terminal eruptions or outbursts [5,6]. Additional spectroscopy from the SOAR 4.1m telescope spanned 400-860 nm [5] showed similarity to the SN impostor SN 1997bs [10]. The blue continuum emission of SN 2010da shortly after outburst was dominated by strong Hα emission, with a full width at half maximum (FWHM) of ∼1000 km s −1 and no evidence of a P Cygni profile, along with other narrow Balmer lines and a possible detection of weak He II λ4686 [5]. These results stood in contrast to those obtained with near-simultaneous GMOS on Gemini-South by Chornock and Berger [4], which observed an Hα FWHM of ∼660 km s −1 and higher-order Balmer lines with clear P-Cygni profiles. These spectral properties led Chornock and Berger [4] to speculate that the SN 2010da event originated in "an LBV-like outburst of a massive star." arXiv:2002.04113v1 [astro-ph.HE]

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“…All these objects have strong and dense outflows. (1), NGC 5408 X-1 (2), NGC 4395 X-1 (3), NGC 1313 X-2 (2), NGC 5204 X-1 (1), NGC 4559 X-7 (1), Holmberg IX X-1 (1) and Holmberg II X-1 (1). The numbers in brackets mean optical telescopes: 1 -Subaru telescope, 2 -VLT (ESO), 3 -Russian BTA telescope.…”

Section: Pos(apcs2016)046mentioning

confidence: 99%

“…Despite their importance in understanding the origin of supermassive black holes that reside in most of present galaxies, the basic nature of ULXs remains unsolved [1,2]. The most popular models for the ULXs involve either intermediate mass black holes (IMBH, 10 3 -10 4 M ) [3] with standard accretion disks or stellar-mass black holes (∼ 10 M ) accreting at super-Eddington rates.…”

Section: Introductionmentioning

confidence: 99%

Ultraluminous X-ray sources. Optical data.

Fabrika¹

2018

Proceedings of Accretion Processes in Cosmic Sources — PoS(APCS2016)

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The origin of Ultraluminous X-ray Sources (ULXs) in external galaxies whose X-ray luminosities exceed those of the brightest black holes in our Galaxy by hundreds and thousands of times is mysterious. The most popular models for the ULXs involve either intermediate mass black holes (IMBHs) or stellar-mass black holes accreting at super-Eddington rates. Here we review the ULX properties. Their X-ray spectra indicate a presence of hot winds in their accretion disks supposing the supercritical accretion. In recent years, new surprising results were discovered in X-ray data, ULX-pulsars and high-velocity outflows up to 0.2 c. They are also in accordance with the superEddington accretion. However, the strongest evidences come from optical spectroscopy. The spectra of the ULX counterparts are very similar to that of SS433, the only known supercritical accretor in our Galaxy. The spectra are apparently of WNL type (late nitrogen Wolf-Rayet stars) or LBV (luminous blue variables) in their hot state, which are very scarce stellar objects. We find that the spectra do not originate from WNL/LBV type donors but from very hot winds from the accretion disks, which have similar physical conditions as the stellar winds from these stars. The results suggest that bona-fide ULXs must constitute a homogeneous class of objects, which most likely have supercritical accretion disks.

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Ultraluminous X-Ray Sources

Cited by 532 publications

References 237 publications

Statistical significance of spectral lag transition in GRB 160625B

Statistical significance of spectral lag transition in GRB 160625B

From SN 2010da to NGC 300 ULX-1: Ten Years of Observations of an Unusual High Mass X-Ray Binary in NGC 300

Ultraluminous X-ray sources. Optical data.

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