Discovery of two eclipsing X-ray binaries in M 51

Wang, Song; Soria, Roberto; Urquhart, Ryan; Liu, Jifeng

doi:10.1093/mnras/sty872

Cited by 9 publications

(9 citation statements)

References 140 publications

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“…To test whether the spectral behavior of ULX-7 changes during the dip, we calculate the hardness ratio (HR) defined as HR = (r h − r s )/(r h + r s ), where r h is the count rate in the 2-7 keV band and r s is that in the count rate at 0.5-2 keV (see Figure 1 (b)). We find no clear hardening during the dip, similar to a few other dipping systems in the same galaxy (Urquhart & Soria 2016;Wang et al 2018).…”

Section: Chandra Light Curvessupporting

confidence: 88%

Possible Periodic Dips in the Pulsating Ultraluminous X-ray Source M51 ULX-7

Hu,

Ueda,

Enoto

2021

Preprint

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We report the discovery of possible periodic X-ray dips in a pulsating ultraluminous X-ray source, M51 ULX-7, with the archival Chandra observations. With ∼20 days of monitoring in the superorbital descending state, we discovered three dips with separations of ∼2 and ∼8 days via the Bayesian block technique. A phase-dispersion minimization and a χ 2 test suggest that the dip is likely recurrent with a period of ∼ 2 days, consistent with the orbital period of M51 ULX-7. We interpret the dip as an obscuring of the emission from the pulsar by the vertical structure on the stream-disk interaction region or the atmosphere of the companion star. Both interpretations suggest the viewing angle to be ∼ 60 degrees. Given that the magnetic field of M51 ULX-7 is moderately high, B ∼ 10 13 G, a low geometric beaming with b 1/2 is sufficient to explain the observed flux and the presence of dips. Obscuration of the stellar wind remains an alternative possible origin and further monitoring of the dips will be required.

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Section: Chandra Light Curvessupporting

confidence: 88%

Possible Periodic Dips in the Pulsating Ultraluminous X-ray Source M51 ULX-7

Hu,

Ueda,

Enoto

2021

Preprint

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“…Then, with the restrictions on the mass of the companion star obtained from optical data, it is possible to determine the mass of a compact object fairly reliably. A good example of this is the eclipsing system CXOM51 J132946.1+471042 (see above), in which a massive donor is paired with a non-pulsating neutron star (Wang et al, 2018). Using HST data, it was possible to detect the optical counterpart of this ULX and obtain restrictions on the donor mass of 20-35 M ⊙ .…”

Section: Optical Counterpartsmentioning

confidence: 99%

Ultraluminous X-Ray Sources

et al. 2021

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Ultraluminous X-ray sources (ULXs) were identified as a separate class of objects in 2000 based on data from the Chandra X-Ray Observatory. These are unique objects: their X-ray luminosities exceed the Eddington limit for a typical stellar-mass black hole. For a long time, the nature of ULXs remained unclear. However, the gradual accumulation of data, new results of X-ray and optical spectroscopy, and the study of the structure and energy of nebulae surrounding ULXs led to the understanding that most of the ultraluminous X-ray sources must be supercritical accretion disks like SS 433. The discovery of neutron stars in a number of objects only increased the confidence of the scientific community in the conclusions obtained, since the presence of neutron stars in such systems clearly indicates a supercritical accretion regime. In this review, we systematize the main facts about the observational manifestations of ULXs and SS 433 in the X-ray and optical ranges and discuss their explanation from the point of view of the supercritical accretion theory.

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“…We conducted a systematic search for possible transits in the Chandra X-ray light curves of XRSs in three galaxies: M51 (a face-on interacting late-type galaxy), M101 (a face-on late-type galaxy), and M104 (an edge-on early-type galaxy with some star formation). These light curves were available because they had recently been studied for other purposes (Wang et al 2018;Urquhart & Soria 2016b,a). It is possible to make discoveries of planetary transits in archived X-ray light curves, because short-term time variability was often not a primary focus of the original observing programs.…”

Section: Search For X-ray Transitsmentioning

confidence: 99%

M51-ULS-1b: The First Candidate for a Planet in an External Galaxy

Stefano¹,

Berndtsson²,

Urquhart³

et al. 2020

Preprint

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Do external galaxies host planetary systems? Many lines of reasoning suggest that the answer must be "yes". In the foreseeable future, however, the question cannot be answered by the methods most successful in our own Galaxy. We report on a different approach which focuses on bright X-ray sources (XRSs). M51-ULS-1b is the first planet candidate to be found because it produces a full, short-lived eclipse of a bright XRS. M51-ULS-1b has a most probable radius slightly smaller than Saturn. It orbits one of the brightest XRSs in the external galaxy M51, the Whirlpool Galaxy, located 8.6 Megaparsecs from Earth. It is the first candidate for a planet in an external galaxy. The binary it orbits, M51-ULS-1, is young and massive. One of the binary components is a stellar remnant, either a neutron star (NS) or black hole (BH), and the other is a massive star. X-ray transits can now be used to discover more planets in external galaxies and also planets orbiting XRSs inside the Milky Way.

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Discovery of two eclipsing X-ray binaries in M 51

Cited by 9 publications

References 140 publications

Possible Periodic Dips in the Pulsating Ultraluminous X-ray Source M51 ULX-7

Possible Periodic Dips in the Pulsating Ultraluminous X-ray Source M51 ULX-7

Ultraluminous X-Ray Sources

M51-ULS-1b: The First Candidate for a Planet in an External Galaxy

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