Mon. Not. R. Astron. Soc., 474, 3000-3008 (2018/March-1)
Multiwavelength follow-up observations of the tidal disruption event candidate 2XMMi J184725.1-631724.
LIN D., STRADER J., CARRASCO E.R., GODET O., GRUPE D., WEBB N.A., BARRET D. and IRWIN J.A.
Abstract (from CDS):
The ultrasoft X-ray flare 2XMMi J184725.1-631724 was serendipitously detected in two XMM-Newton observations in 2006 and 2007, with a peak luminosity of 6 x 1043 erg s–1. It was suggested to be a tidal disruption event (TDE) because its position is consistent with the centre of an inactive galaxy. It is the only known X-ray TDE candidate whose X-ray spectra showed evidence of a weak steep power-law component besides a dominant supersoft thermal disc. We have carried out multiwavelength follow-up observations of the event. Multiple X-ray monitorings show that the X-ray luminosity has decayed significantly after 2011. Especially, in our deep Chandra observation in 2013, we detected a very faint counterpart that supports the nuclear origin of 2XMMi J184725.1-631724 but had an X-ray flux a factor of ∼1000 lower than in the peak of the event. Compared with follow-up ultraviolet (UV) observations, we found that there might be some enhanced UV emission associated with the TDE in the first XMM-Newton observation. We also obtained a high-quality UV-optical spectrum with the Southern Astrophysical Research (SOAR) Telescope and put a very tight constraint on the persistent nuclear activity, with a persistent X-ray luminosity expected to be lower than the peak of the flare by a factor of >2700. Therefore, our multiwavelength follow-up observations strongly support the TDE explanation of the event.
© 2017 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
accretion, accretion discs - black hole physics - galaxies: individual: 2XMMi J184725.1-631724 - X-rays: galaxies
Fig. 1: [LSC2018] Source 2 N=1.
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