Disentangling the neighbouring pulsars SXP 15.3 and SXP 305

Monageng, I. M.; Coe, M. J.; Townsend, L. J.; Laycock, S.; Kennea, J. A.; Roy, Ankur; Udalski, A.; Bhattacharya, Sayantan; Christodoulou, Dimitris M.; Buckley, D.; Evans, P. A.

doi:10.1093/mnras/stac106

Cited by 2 publications

(2 citation statements)

References 39 publications

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“…Disk material may be pushed away and towards us during the two encounters that could be partly be hidden by the disk and naturally lead to two different optical outbursts. A similar, but in some respects different, phenomenon was reported by Monageng et al (2022) for the BeXRB pulsar SXP 15.3 in the SMC. Also for that system, two periodicities, 74.5 d and 148 d, were found from optical (OGLE) and X-rays (Swift).…”

Section: Xmmu J0453151-693242supporting

confidence: 78%

Three new high-mass X-ray binaries in the Large Magellanic Cloud

Haberl

Maitra

Vasilopoulos

et al. 2022

A&A

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Context. The Magellanic Clouds host a large population of high-mass X-ray binary (HMXB) systems, and although the Large Magellanic Cloud (LMC) is an order of magnitude more massive than the Small Magellanic Cloud, there are significantly fewer known HMXBs in the former. Aims. We conducted a search for new HMXBs in XMM-Newton observations that were performed with the aim of investigating supernova remnant candidates in the supergiant shells LMC5 and LMC7. The three observed fields are located in regions that have not been widely explored in the X-ray band. Methods. We analysed the XMM-Newton data to look for sources with hard X-ray spectrum and their counterparts with optical colours and brightness values that are typical of HMXBs. Results. We report the discovery of three new Be/X-ray binaries, two of them showing pulsations in their X-ray flux. With a luminosity of 6.5 × 1034 erg s−1, we see that XMMU J045315.1−693242 in LMC7 was relatively X-ray faint. The long-term OGLE I-band light curve of the V = 15.5 mag counterpart suggests a 49.6 day or 24.8 day orbital period for the binary system. Then, XMMU J045736.9−692727, which is also located in LMC7, was brighter, with a luminosity of 5.6 × 1035 erg s−1 and hard spectrum with a power-law photon index of 0.63. The X-ray flux revealed clear pulsations with a period of 317.7 s. We obtained optical high resolution spectra from the V = 14.2 mag counterpart using the SALT-HRS spectrograph. Hα and Hβ were observed in emission with complex line profiles and equivalent widths of −8.0 Å and −1.3 Å, respectively. The I-band light curve obtained from OGLE shows a series of four strong outbursts followed by a sudden drop in brightness by more than 1 mag within 73–165 days and a recovery to the level from before the outbursts. RX J0524.2−6620, previously classified as X-ray binary candidate, is located at the eastern part of LMC5. We report the discovery of 360.7 s pulsations. During the XMM-Newton observation the luminosity was at ∼4 × 1035 erg s−1 and the source showed a hard spectrum with a power-law photon index of 0.78. The Hα emission line profile obtained from SALT-HRS is characterised by two broad peaks with a separation corresponding to ∼178 km s−1, along with an equivalent width of −4.2 Å. The long-term OGLE I-band light curve of the V = 14.9 mag counterpart reveals a quasi-periodic flaring activity while the colour evolution during the flares follows a hysteresis loop with redder colour during the rise. Based on the modelling the Hα line profiles measured from XMMU J045736.9−692727 and RX J0524.2−6620, we derived constraints on the size of the Be disks. Conclusions. Our discovery of two pulsars among three new Be/X-ray binaries increases the number of known HMXB pulsars in the LMC to 25.

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Section: Xmmu J0453151-693242supporting

confidence: 78%

Three new high-mass X-ray binaries in the Large Magellanic Cloud

Haberl

Maitra

Vasilopoulos

et al. 2022

A&A

Self Cite

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“…S-CUBED also observes all tiles using the Ultraviolet/ Optical Telescope (UVOT; Roming et al 2005) in the uvw1 band centered at 2600 Å. The archive of X-ray and UV photometric data taken by S-CUBED has proved to be an invaluable resource for discovering previously undetected BeXRBs (Kennea et al 2020(Kennea et al , 2021Monageng et al 2020;Coe et al 2021;Monageng et al 2022). It was through an X-ray selected search of the S-CUBED archive that Swift J010902.6-723710 was first identified as a candidate source in the summer of 2023, several months before it entered outburst during 2023 October.…”

Section: Introductionmentioning

confidence: 99%

Discovery of a Rare Eclipsing Be/X-Ray Binary System, Swift J010902.6-723710 = SXP 182

Gaudin,

Kennea,

Coe

et al. 2024

ApJL

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We report on the discovery of Swift J010902.6-723710, a rare eclipsing Be/X-ray Binary system by the Swift SMC Survey (S-CUBED). Swift J010902.6-723710 was discovered via weekly S-CUBED monitoring observations when it was observed to enter a state of X-ray outburst on 2023 October 10. X-ray emission was found to be modulated by a 182 s period. Optical spectroscopy is used to confirm the presence of a highly inclined circumstellar disk surrounding a B0-0.5Ve optical companion. Historical UV and IR photometry is then used to identify strong eclipse-like features reoccurring in both light curves with a 60.623 day period, which is adopted as the orbital period of the system. Eclipsing behavior is found to be the result of a large accretion disk surrounding the neutron star. Eclipses are produced when the disk passes in front of the OBe companion, blocking light from both the stellar surface and circumstellar disk. This is only the third Be/X-ray binary to have confirmed eclipses. We note that this rare behavior provides an important opportunity to constrain the physical parameters of a Be/X-ray binary with greater accuracy than is possible in noneclipsing systems.

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Disentangling the neighbouring pulsars SXP 15.3 and SXP 305

Cited by 2 publications

References 39 publications

Three new high-mass X-ray binaries in the Large Magellanic Cloud

Three new high-mass X-ray binaries in the Large Magellanic Cloud

Discovery of a Rare Eclipsing Be/X-Ray Binary System, Swift J010902.6-723710 = SXP 182

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