Two Eclipsing Ultraluminous X-Ray Sources in M51

Urquhart, Ryan; Soria, Roberto

doi:10.3847/0004-637x/831/1/56

Cited by 32 publications

(41 citation statements)

References 80 publications

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“…Such beaming must follow from the presence of an equatorial optically thick wind (Pinto, Middleton & Fabian 2016) and is consistent with the general lack of eclipses in ULXs (Middleton & King 2016, although see the recently discovered eclipsing ULXs by Urquhart & Soria 2016).…”

Section: Introductionsupporting

confidence: 64%

Modelling the light curves of ultraluminous X-ray sources as precession

Dauser

Middleton

Wilms

2016

Mon. Not. R. Astron. Soc.

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We present a freely available XSPEC model for the modulations seen in the long-term light curves of multiple ultraluminous X-ray sources (ULXs). By incorporating the physics of multiple electron scatterings (ray traced with a Monte-Carlo routine), we go beyond analytical predictions and show that the geometrical beaming of radiation in the conical outflow can be more than a factor of 100 for opening angles smaller than 10• . We apply our new model to the longterm, well sampled Swift light curve of the recently confirmed ULX pulsar NGC 5907 X-1 with an established period of 78 days. Our results suggest that geometrical beaming together with a slight precession of the conical wind can describe the light curve with a consistent set of parameters for the wind. The small opening angle of roughly 10−13• implies a highly super-critical flow and boosting factors at the order of B = 60-90 that would yield a fairly low surface magnetic field strength of 2 × 10 10 Gauss.

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Section: Introductionsupporting

confidence: 64%

Modelling the light curves of ultraluminous X-ray sources as precession

Dauser

Middleton

Wilms

2016

Mon. Not. R. Astron. Soc.

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“…Another scenario is that the residual soft X-ray emission comes from the photosphere of the optically thick outflows driven by the super-Eddington source. Such thermal component has been invoked to explain the spectra of ultraluminous supersoft sources and the "soft excess" in ULX spectra (Tao et al 2019;Soria & Kong 2016;Urquhart & Soria 2016;Middleton et al 2015). It is generally consistent with a blackbody spectrum at temperatures ≈50-120 eV for supersoft sources, and ≈0.1-0.4 keV for ULXs, with a soft X-ray luminosity from ∼10 38 erg s −1 up to a few 10 39 erg s −1 (Zhou et al 2019;Urquhart & Soria 2016).…”

Section: Residual Emission In the Eclipsementioning

confidence: 99%

CG X-1: An Eclipsing Wolf–Rayet ULX in the Circinus Galaxy

Qiu

Soria

Wang

et al. 2019

ApJ

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We investigated the time-variability and spectral properties of the eclipsing X-ray source Circinus Galaxy X-1 (GG X-1), using Chandra, XMM-Newton and ROSAT. We phase-connected the lightcurves observed over 20 years, and obtained a best-fitting period P = (25, 970.0±0.1) s ≈7.2 hr, and a period derivativeṖ /P = (10.2±4.6)×10 −7 yr −1 . The X-ray lightcurve shows asymmetric eclipses, with sharp ingresses and slow, irregular egresses. The eclipse profile and duration vary substantially from cycle to cycle. We show that the X-ray spectra are consistent with a power-law-like component, absorbed by neutral and ionized Compton-thin material, and by a Compton-thick, partial-covering medium, responsible for the irregular dips. The high X-ray/optical flux ratio rules out the possibility that CG X-1 is a foreground Cataclysmic Variable; in agreement with previous studies, we conclude that it is the first example of a compact ultraluminous X-ray source fed by a Wolf-Rayet star or stripped Helium star. Its unocculted luminosity varies between ≈4 ×10 39 erg s −1 and ≈3 ×10 40 erg s −1 . Both the donor star and the super-Eddington compact object drive powerful outflows: we suggest that the occulting clouds are produced in the wind-wind collision region and in the bow shock in front of the compact object. Among the rare sample of Wolf-Rayet X-ray binaries, CG X-1 is an exceptional target for studies of super-critical accretion and close binary evolution; it is also a likely progenitor of gravitational wave events.

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“…In this work, we present the results of a search for optical identification of one of the ULXs (X-1) of the galaxy NGC 2500 by using the archival images of HST/WFC3/UVIS camera with various filters. NGC 2500 is a spiral galaxy (type SB(rs)d) with a low surface brightness at a distance of ∼10 Mpc (Tully 1988). Two ULXs were catalogued by Swartz et al (2011) in this galaxy.…”

Section: Introductionmentioning

confidence: 99%

Optical counterparts of an ultraluminous X-Ray Source X-1 in NGC 2500

Aksaker

Akyüz

Avdan

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present the results of a search for optical counterparts of ultraluminous X-ray source (ULX) X-1 in the nearby galaxy NGC 2500 by using archival images taken with the Hubble Space Telescope (HST) Wide Field Camera (WFC3)/UVIS. Four optical sources have been identified as possible counterparts within the 2σ error radius of 0. ′′ 3 in the images. However, only two of them were investigated as candidates for counterparts due to their point-like features and their identification in various filters. These two faint candidates have absolute magnitudes of M V ≈ -3.4 and -3.7. Also possible spectral classes of them were determined as B type main sequence stars. The ages and the masses of the candidates from Color Magnitude Diagram (CMD) were estimated as 45 Myr and 7 M ⊙ , respectively. The spectral energy distributions (SEDs) of two candidates were modeled by a power-law spectrum with a photon index (α) ∼1.5. The spectra with such slopes could be interpreted as an evidence of reprocessing of the X-rays in the outer part of the disk that generates optical emission.

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Two Eclipsing Ultraluminous X-Ray Sources in M51

Cited by 32 publications

References 80 publications

Modelling the light curves of ultraluminous X-ray sources as precession

Modelling the light curves of ultraluminous X-ray sources as precession

CG X-1: An Eclipsing Wolf–Rayet ULX in the Circinus Galaxy

Optical counterparts of an ultraluminous X-Ray Source X-1 in NGC 2500

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