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Title: Multi-wavelength observations of the Be/X-ray binary IGR J01217−7257 (=SXP 2.16) during outburst
Authors: Boon, C. M.
Bird, A. J.
Coe, M. J.
Corbet, R. H. D.
Evans, P. A.
Kennea, J. A.
Krimm, H. A.
Laycock, S. G. T.
Udalski, A.
First Published: 7-Dec-2016
Publisher: Oxford University Press (OUP), Royal Astronomical Society
Citation: Monthly Notices of the Royal Astronomical Society, 2016
Abstract: We present simultaneous, multi-wavelength observations of the Small Magellanic Cloud Be/XRB IGR J01217−7257 (=SXP 2.16) during outbursts in 2014, 2015 and 2016. We also present the results of RXTE observations of the Small Magellanic Cloud during which the source was initially discovered with a periodicity of 2.1652±0.0001 seconds which we associate with the spin period of the neutron star. A systematic temporal analysis of long term Swift/BAT data reveals a periodic signal of 82.5±0.7 days, in contrast with a similar analysis of long base line OGLE I-band light curves which reveals an 83.67±0.05 days also found in this work. Interpreting the longer X-ray periodicity as indicative of binary motion of the neutron star, we find that outbursts detected by INTEGRAL and Swift between 2014 and 2016 are consistent with Type I outbursts seen in Be/XRBs, occurring around periastron. Comparing these outbursts with the OGLE data, we see a clear correlation between outburst occurrence and increasing I-band flux. A periodic analysis of subdivisions of OGLE data reveals three epochs during which short periodicities of ∼1 day are significantly detected which we suggest are non-radial pulsations (NRPs) of the companion star. These seasons immediately precede those exhibiting clear outburst behaviour, supporting the suggested association between the NRPs, decretion disk growth and the onset of Type I outbursts.
DOI Link: 10.1093/mnras/stw3169
ISSN: 0035-8711
eISSN: 1365-2966
Version: Post-print
Status: Peer-reviewed
Type: Journal Article
Rights: Creative Commons “Attribution Non-Commercial No Derivatives” licence CC BY-NC-ND, further details of which can be found via the following link: Archived with reference to SHERPA/RoMEO and publisher website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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