The 2016 super-Eddington outburst of SMC X-3: X-ray and optical properties and system parameters

dc.contributor.authorTownsend, L J
dc.contributor.authorMcBride, V A
dc.contributor.authorBuckley, D A H
dc.contributor.authorEvans, P A
dc.contributor.authorUdalski, A
dc.date.accessioned2021-10-08T07:08:25Z
dc.date.available2021-10-08T07:08:25Z
dc.date.issued2017
dc.description.abstractOn 2016 July 30 (MJD 57599), observations of the Small Magellanic Cloud by Swift/XRT found an increase in X-ray counts coming from a position consistent with the Be/X-ray binary pulsar SMC X-3. Follow-up observations on 2016 August 3 (MJD 57603) and 2016 August 10 (MJD 57610) revealed a rapidly increasing count rate and confirmed the onset of a new X-ray outburst from the system. Further monitoring by Swift began to uncover the enormity of the outburst, which peaked at 1.2 x 1039 erg/s on 2016 August 25 (MJD 57625). The system then began a gradual decline in flux that was still continuing over 5 months after the initial detection. We explore the X-ray and optical behaviour of SMC X-3 between 2016 July 30 and 2016 December 18 during this super-Eddington outburst. We apply a binary model to the spin-period evolution that takes into account the complex accretion changes over the outburst, to solve for the orbital parameters. Our results show SMC X-3 to be a system with a moderately low eccentricity amongst the Be/X-ray binary systems and to have a dynamically determined orbital period statistically consistent with the prominent period measured in the OGLE optical light curve. Our optical and X-ray derived ephemerides show that the peak in optical flux occurs roughly 6 days after periastron. The measured increase in I-band flux from the counterpart during the outburst is reflected in the measured equivalent width of the H-alpha line emission, though the H-alpha emission itself seems variable on sub-day time-scales, possibly due to the NS interacting with an inhomogeneous disc.
dc.identifier.apacitationTownsend, L. J., McBride, V. A., Buckley, D. A. H., Evans, P. A., & Udalski, A. (2017). The 2016 super-Eddington outburst of SMC X-3: X-ray and optical properties and system parameters. <i>Monthly Notices of the Royal Astronomical Society</i>, 471(4), 3878 - 3887. http://hdl.handle.net/11427/34578en_ZA
dc.identifier.chicagocitationTownsend, L J, V A McBride, D A H Buckley, P A Evans, and A Udalski "The 2016 super-Eddington outburst of SMC X-3: X-ray and optical properties and system parameters." <i>Monthly Notices of the Royal Astronomical Society</i> 471, 4. (2017): 3878 - 3887. http://hdl.handle.net/11427/34578en_ZA
dc.identifier.citationTownsend, L.J., McBride, V.A., Buckley, D.A.H., Evans, P.A. & Udalski, A. 2017. The 2016 super-Eddington outburst of SMC X-3: X-ray and optical properties and system parameters. <i>Monthly Notices of the Royal Astronomical Society.</i> 471(4):3878 - 3887. http://hdl.handle.net/11427/34578en_ZA
dc.identifier.issn0035-8711
dc.identifier.issn1365-2966
dc.identifier.ris TY - Journal Article AU - Townsend, L J AU - McBride, V A AU - Buckley, D A H AU - Evans, P A AU - Udalski, A AB - On 2016 July 30 (MJD 57599), observations of the Small Magellanic Cloud by Swift/XRT found an increase in X-ray counts coming from a position consistent with the Be/X-ray binary pulsar SMC X-3. Follow-up observations on 2016 August 3 (MJD 57603) and 2016 August 10 (MJD 57610) revealed a rapidly increasing count rate and confirmed the onset of a new X-ray outburst from the system. Further monitoring by Swift began to uncover the enormity of the outburst, which peaked at 1.2 x 1039 erg/s on 2016 August 25 (MJD 57625). The system then began a gradual decline in flux that was still continuing over 5 months after the initial detection. We explore the X-ray and optical behaviour of SMC X-3 between 2016 July 30 and 2016 December 18 during this super-Eddington outburst. We apply a binary model to the spin-period evolution that takes into account the complex accretion changes over the outburst, to solve for the orbital parameters. Our results show SMC X-3 to be a system with a moderately low eccentricity amongst the Be/X-ray binary systems and to have a dynamically determined orbital period statistically consistent with the prominent period measured in the OGLE optical light curve. Our optical and X-ray derived ephemerides show that the peak in optical flux occurs roughly 6 days after periastron. The measured increase in I-band flux from the counterpart during the outburst is reflected in the measured equivalent width of the H-alpha line emission, though the H-alpha emission itself seems variable on sub-day time-scales, possibly due to the NS interacting with an inhomogeneous disc. DA - 2017 DB - OpenUCT DP - University of Cape Town IS - 4 J1 - Monthly Notices of the Royal Astronomical Society LK - https://open.uct.ac.za PY - 2017 SM - 0035-8711 SM - 1365-2966 T1 - The 2016 super-Eddington outburst of SMC X-3: X-ray and optical properties and system parameters TI - The 2016 super-Eddington outburst of SMC X-3: X-ray and optical properties and system parameters UR - http://hdl.handle.net/11427/34578 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/34578
dc.identifier.vancouvercitationTownsend LJ, McBride VA, Buckley DAH, Evans PA, Udalski A. The 2016 super-Eddington outburst of SMC X-3: X-ray and optical properties and system parameters. Monthly Notices of the Royal Astronomical Society. 2017;471(4):3878 - 3887. http://hdl.handle.net/11427/34578.en_ZA
dc.language.isoeng
dc.publisher.departmentDepartment of Astronomy
dc.publisher.facultyFaculty of Science
dc.sourceMonthly Notices of the Royal Astronomical Society
dc.source.journalissue4
dc.source.journalvolume471
dc.source.pagination3878 - 3887
dc.source.urihttps://dx.doi.org/10.1093/mnras/stx1865
dc.subject.otherastro-ph.HE
dc.subject.otherJournal Article
dc.titleThe 2016 super-Eddington outburst of SMC X-3: X-ray and optical properties and system parameters
dc.typeJournal Article
uct.type.publicationResearch
uct.type.resourceJournal Article
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