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transient ultraluminous X-ray source, ULX-4, in M51.
- Source :
- Monthly Notices of the Royal Astronomical Society; Mar2022, Vol. 510 Issue 3, p4355-4369, 15p
- Publication Year :
- 2022
-
Abstract
- We present the results of a temporal and spectral analysis of the transient source ULX-4 in the galaxy M51. The data used were drawn from Chandra ,  XMM–Newton , and Swift-XRT archives, spanning the years 2000–2019.. The X-ray flux of the source is seen to vary by two orders of magnitudes within a month but a short-term variability was not observed over the time intervals of 100–2000 s in the 0.3–10 keV energy band. We find some evidence for the existence of bi-modality feature in the flux distribution of ULX-4. We identified two optical sources as possible counterparts within an error radius of 0 |${_{.}^{\prime\prime}}$| 18 at 95 |${{\ \rm per\ cent}}$| confidence level for ULX-4 based on the archival Hubble Space Telescope (HST) /ACS and HST /WFC3 data. Blackbody fits of the spectral energy distributions (SEDs) indicate the spectral type to be B-type stars. One of these counterparts exhibits a low-amplitude optical periodicity of 264 ± 37 d in the F606W filter; if we assume this apparent periodicity is associated with the orbital motion of the donor, then it is more likely that the donor is a red supergiant satisfying the long periodicity and accretion via Roche lobe overflow. Consequently, the SED would then have to be interpreted as a superposition of emissions from a cold donor and a hot flow component, most likely from an accretion disc. If, on the other hand, the periodicity is superorbital in nature i.e. due to possible interactions of the compact object with a circumstellar disc, the donor could then be a Be/X star hosting a neutron star. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00358711
- Volume :
- 510
- Issue :
- 3
- Database :
- Complementary Index
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Publication Type :
- Academic Journal
- Accession number :
- 154976279
- Full Text :
- https://doi.org/10.1093/mnras/stab3693