The 2016 super-Eddington outburst of SMC X-3

X-ray and optical properties and system parameters

L. J. Townsend, Jamie A. Kennea, M. J. Coe, V. A. McBride, D. A.H. Buckley, P. A. Evans, A. Udalski

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

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 × 1039 erg s-1 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 d after periastron. The measured increase in I-band flux from the counterpart during the outburst is reflected in the measured equivalent width of the Hα line emission, though the Hα emission itself seems variable on sub-day time-scales, possibly due to the NS interacting with an inhomogeneous disc.

Original languageEnglish (US)
Pages (from-to)3878-3887
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume471
Issue number4
DOIs
StatePublished - Jan 1 2017

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outburst
optical property
optical properties
x rays
H lines
ephemerides
orbitals
Magellanic clouds
daytime
eccentricity
pulsars
erg
light curve
parameter
accretion
timescale
monitoring

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Townsend, L. J. ; Kennea, Jamie A. ; Coe, M. J. ; McBride, V. A. ; Buckley, D. A.H. ; Evans, P. A. ; Udalski, A. / The 2016 super-Eddington outburst of SMC X-3 : X-ray and optical properties and system parameters. In: Monthly Notices of the Royal Astronomical Society. 2017 ; Vol. 471, No. 4. pp. 3878-3887.
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abstract = "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 × 1039 erg s-1 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 d after periastron. The measured increase in I-band flux from the counterpart during the outburst is reflected in the measured equivalent width of the Hα line emission, though the Hα emission itself seems variable on sub-day time-scales, possibly due to the NS interacting with an inhomogeneous disc.",
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The 2016 super-Eddington outburst of SMC X-3 : X-ray and optical properties and system parameters. / Townsend, L. J.; Kennea, Jamie A.; Coe, M. J.; McBride, V. A.; Buckley, D. A.H.; Evans, P. A.; Udalski, A.

In: Monthly Notices of the Royal Astronomical Society, Vol. 471, No. 4, 01.01.2017, p. 3878-3887.

Research output: Contribution to journalArticle

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AU - Townsend, L. J.

AU - Kennea, Jamie A.

AU - Coe, M. J.

AU - McBride, V. A.

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