A Long Look at the Be/X‐Ray Binaries of the Small Magellanic Cloud

Galache, J. L.; Corbet, R. H. D.; Coe, M. J.; Laycock, S.; Schurch, M. P. E.; Markwardt, C. B.; Marshall, F. E.; Lochner, J. C.

doi:10.1086/587743

Cited by 81 publications

(212 citation statements)

References 67 publications

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“…Rajoelimanana et al (2011b) analysed the OGLE III data, which revealed a significant peak at 171 ± 0.3 d in the power spectra, which is less than half the reported X-ray period. Galache et al (2008) already noted that the X-ray period is longer than would be expected given its spin period position in the Corbet diagram (Corbet 1984;Laycock et al 2005, see also Fig. 8, in which SXP82.4 is found as the right-most open red circle).…”

Section: Update On Individual Bexrb Pulsarsmentioning

confidence: 86%

“…Description Liu et al (2005) HMXB catalogue of the Magellanic Clouds Coe et al (2005) Optical properties of HMXBs in the SMC Shtykovskiy & Gilfanov (2005) HMXBs in archival XMM-Newton data McGowan et al (2008b) Chandra SMC Wing survey Galache et al (2008) RXTE observations of SMC pulsars McBride et al (2008) Optical spectroscopy of BeXRB pulsars in the SMC New BeXRBs from XMM-Newton observations in Antoniou et al (2009b Optical identification of Chandra sources Antoniou et al (2009a) Optical spectroscopy of BeXRBs in the SMC Laycock et al (2010) Catalogue of SMC sources from deep Chandra observations a Rajoelimanana et al (2011b) Long-term optical variability of HMXB pulsars in the SMC Sturm et al (2013c) XMM-Newton survey of the SMC Coe & Kirk (2015) BeXRB pulsars in the SMC Notes. (a) Includes detections down to two net counts.…”

Section: Referencementioning

confidence: 99%

“…From the RXTE SMC monitoring Galache et al (2008) identified an outburst pattern with a period of 362.3 ± 4.1 d in X-rays. Rajoelimanana et al (2011b) analysed the OGLE III data, which revealed a significant peak at 171 ± 0.3 d in the power spectra, which is less than half the reported X-ray period.…”

Section: Update On Individual Bexrb Pulsarsmentioning

confidence: 99%

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High-mass X-ray binaries in the Small Magellanic Cloud

Haberl

Sturm

2016

A&A

157

176

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Aims. The last comprehensive catalogue of high-mass X-ray binaries in the Small Magellanic Cloud (SMC) was published about ten years ago. Since then new such systems were discovered, mainly by X-ray observations with Chandra and XMM-Newton. For the majority of the proposed HMXBs in the SMC no X-ray pulsations were discovered as yet, and unless other properties of the X-ray source and/or the optical counterpart confirm their HMXB nature, they remain only candidate HMXBs. Methods. From a literature search we collected a catalogue of 148 confirmed and candidate HMXBs in the SMC and investigated their properties to shed light on their real nature. Based on the sample of well-established HMXBs (the pulsars), we investigated which observed properties are most appropriate for a reliable classification. We defined different levels of confidence for a genuine HMXB based on spectral and temporal characteristics of the X-ray sources and colour-magnitude diagrams from the optical to the infrared of their likely counterparts. We also took the uncertainty in the X-ray position into account. Results. We identify 27 objects that probably are misidentified because they lack an infrared excess of the proposed counterpart. They were mainly X-ray sources with a large positional uncertainty. This is supported by additional information obtained from more recent observations. Our catalogue comprises 121 relatively high-confidence HMXBs (the vast majority with Be companion stars). About half of the objects show X-ray pulsations, while for the rest no pulsations are known as yet. A comparison of the two subsamples suggests that long pulse periods in excess of a few 100 s are expected for the "non-pulsars", which are most likely undetected because of aperiodic variability on similar timescales and insufficiently long X-ray observations. The highest X-ray variability together with the lowest observed minimum fluxes for short-period pulsars indicate that in addition to the eccentricity of the orbit, its inclination against the plane of the Be star circum-stellar disc plays a major role in determining the outburst behaviour. Conclusions. The large population of HMXBs in the SMC, in particular Be X-ray binaries, provides the largest homogeneous sample of such systems for statistical population studies.

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Section: Update On Individual Bexrb Pulsarsmentioning

confidence: 86%

Section: Referencementioning

confidence: 99%

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High-mass X-ray binaries in the Small Magellanic Cloud

Haberl

Sturm

2016

A&A

157

176

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“…(SMC) was monitored with RXTE for about 14 years (Galache et al 2008). Therefore, only nine HMXB X-ray pulsars are known to date in the LMC, which inhibits a statistical comparison of this sample with those of the Galaxy and the SMC.…”

Section: Introductionmentioning

confidence: 99%

Discovery of the neutron star spin and a possible orbital period from the Be/X-ray binary IGR J05414-6858 in the LMC

Sturm

Haberl

Rau

et al. 2012

A&A

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Context. The number of known Be/X-ray binaries in the Large Magellanic Cloud is small compared to the observed population of the Galaxy or the Small Magellanic Cloud. The discovery of a system in outburst provides the rare opportunity to measure its X-ray properties in detail. Aims. IGR J05414-6858 was discovered in 2010 with INTEGRAL and was found in another outburst with the Swift satellite in 2011.To characterise the system, we analysed the data from a follow-up XMM-Newton target of opportunity observation of the 2011 outburst and investigated the stellar counterpart with photometry and spectroscopy. Methods. We modelled the X-ray spectra from the EPIC instruments on XMM-Newton and compared them with Swift archival data. We searched for periodicities and variability in the X-ray and optical light curves. The optical counterpart was classified using spectroscopy obtained with ESO's Faint Object Spectrograph at NTT. Results. The X-ray spectra as seen in 2011 are relatively hard with a photon index of ∼0.3−0.4 and show only low absorption. They deviate significantly from earlier spectra of a probable type-II outburst in 2010. The neutron star spin period of P spin = 4.4208 s was discovered with EPIC-pn. The I-band light curve revealed a transition from a low to a high state around MJD 54 500. The optical counterpart is classified as B0-1 IIIe and shows Hα emission and a variable near-infrared excess that vanishes during the 2010 outburst. In the optical high state, we found a periodicity at 19.9 days, probably caused by binarity and indicating the orbital period.

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“…Corcoran 2005) or enhanced accretion rates in X-ray binaries (e.g. Galache et al 2008). Such repetitive, periodic flaring is not immediately apparent in the lightcurve of VFTS 399, although this does not preclude its future occurrence since, in the case of X-ray binaries, such behaviour is observed to be transient.…”

Section: Lombmentioning

confidence: 99%

The VLT-FLAMES Tarantula survey

Clark

Bartlett

Broos

et al. 2015

A&A

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Context. The stellar population of the 30 Doradus star-forming region in the Large Magellanic Cloud contains a subset of apparently single, rapidly rotating O-type stars. The physical processes leading to the formation of this cohort are currently uncertain. Aims. One member of this group, the late O-type star VFTS 399, is found to be unexpectedly X-ray bright for its bolometric luminosity − in this study we aim to determine its physical nature and the cause of this behaviour. Methods. To accomplish this we performed a time-resolved analysis of optical, infrared and X-ray observations. Results. We found VFTS 399 to be an aperiodic photometric variable with an apparent near-IR excess. Its optical spectrum demonstrates complex emission profiles in the lower Balmer series and select He i lines − taken together these suggest an OeBe classification.The highly variable X-ray luminosity is too great to be produced by a single star, while the hard, non-thermal nature suggests the presence of an accreting relativistic companion. Finally, the detection of periodic modulation of the X-ray lightcurve is most naturally explained under the assumption that the accretor is a neutron star. Conclusions. VFTS 399 appears to be the first high-mass X-ray binary identified within 30 Dor, sharing many observational characteristics with classical Be X-ray binaries. Comparison of the current properties of VFTS 399 to binary-evolution models suggests a progenitor mass 25 M for the putative neutron star, which may host a magnetic field comparable in strength to those of magnetars. VFTS 399 is now the second member of the cohort of rapidly rotating "single" O-type stars in 30 Dor to show evidence of binary interaction resulting in spin-up, suggesting that this may be a viable evolutionary pathway for the formation of a subset of this stellar population.

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A Long Look at the Be/X‐Ray Binaries of the Small Magellanic Cloud

Cited by 81 publications

References 67 publications

High-mass X-ray binaries in the Small Magellanic Cloud

High-mass X-ray binaries in the Small Magellanic Cloud

Discovery of the neutron star spin and a possible orbital period from the Be/X-ray binary IGR J05414-6858 in the LMC

The VLT-FLAMES Tarantula survey

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