A tidal disruption-like X-ray flare from the quiescent galaxy SDSS J120136.02+300305.5

Abstract

Aims. The study of tidal disruption flares from galactic nuclei has historically been hampered by a lack of high quality spectral observations taken around the peak of the outburst. Here we introduce the first results from a program designed to identify tidal disruption events at their peak by making near-real-time comparisons of the flux seen in XMM-Newton slew sources with that seen in ROSAT. Methods. Flaring extragalactic sources, which do not appear to be AGN, are monitored with Swift and XMM-Newton to track their temporal and spectral evolution. Timely optical observations are made to monitor the reaction of circumnuclear material to the X-ray flare.Results. SDSS J120136.02+300305.5 was detected in an XMM-Newton slew from June 2010 with a flux 56 times higher than an upper limit from ROSAT, corresponding to L X ∼ 3 × 10 44 erg s −1 . It has the optical spectrum of a quiescent galaxy (z = 0.146). Overall the X-ray flux has evolved consistently with the canonical t −5/3 model, expected for returning stellar debris, fading by a factor ∼300 over 300 days. In detail the source is very variable and became invisible to Swift between 27 and 48 days after discovery, perhaps due to self-absorption. The X-ray spectrum is soft but is not the expected tail of optically thick thermal emission. It may be fit with a Bremsstrahlung or double-power-law model and is seen to soften with time and declining flux. Optical spectra taken 12 days and 11 months after discovery indicate a deficit of material in the broad line and coronal line regions of this galaxy, while a deep radio non-detection implies that a jet was not launched during this event.

Tidal disruption of a super-Jupiter by a massive black hole

“…Supernova explosions and expanding winds may emit hard X-ray flares (Immler & Lewin 2003;Chandra et al 2009;Saxton et al 2012). Supernova peak X-ray luminosities have been observed up to 10 40 erg/s with a decline usually following a t −(0.5−1) scaling.…”

A well-monitored, X-ray selected, tidal disruption event

“…In [12] we showed that the combined EPIC-pn, and MOS spectra for the three XMM-Newton observations are not well modelled by multi-coloured black-body emission. They were fit well by Bremsstrahlung radiation whose temperature declined from 390 ± 10 to 290 ± 20 to 180 +60 −30 eV as the X-ray luminosity dropped from 4.7×10 43 to 1.1 × 10 43 to 2.3 × 10 42 ergs/s.…”

“…In parallel, 30ks XMM-Newton pointed observations were triggered on 2010-06-22, 2010-11-23 and 2010-12-23. First results from these observations have been published in [12]. Further analyses, presented here, have been made with the XMM-Newton Science Analysis System (SAS v12; [3]).…”

Large decay of X-ray flux in 2XMM J123103.2+110648: evidence for a tidal disruption event

“…The first XMM-Newton observation was even fainter (by a factor of 2) than the other two XMM-Newton observations 2.4 years later. The X-ray spectral softening observed in XJ1231+1106 with the decrease in the X-ray flux has been observed in some TDE candidates (Lin et al 2011;Saxton et al 2012), but not in all cases. In the well monitored TDE candidate ASASSN-14li, steady blackbody temperatures in the X-ray spectra were observed despite the drop of the X-ray flux nearly by an order of magnitude (Miller et al 2015).…”