A bright X-ray TDE candidate SRGet J143359.25+400638.5 in SDSS J143359.16+400636.0
ATel #13494; I. Khabibullin, R. Sunyaev, E. Churazov, M. Gilfanov, P. Medvedev, S. Sazonov on behalf of the Russian SRG/eROSITA Consortium
on 17 Feb 2020; 16:24 UT
Credential Certification: Eugene Churazov (churazov@gmail.com)
Subjects: Optical, X-ray, Tidal Disruption Event
We report on SRG/eROSITA detection of a very bright (Fx[0.3-8 keV]=6.5e-12 erg/s/cm^2)
and soft (kT_diskbb=0.29 keV, N_H~1.5x10^20 cm^-2) X-ray source SRGet J143359.25 +400638.5 (RA,Dec=218.49686,+40.11069)
centered on galaxy SDSS J143359.16+400636 (with better than 10 arcsec accuracy).
In the course of the all-sky survey, SRG/eROSITA observed the source for the first time on 2019-12-27
and then scanned it 10 more times with an interval of 4 hours (each time with exposure of ~40 seconds).
No significant variation of the flux level or spectral shape has been observed.
Taking the distance to the galaxy equal to z=0.08 (according to the photometric redshift estimate from Brescia et al 2014),
the inferred X-ray luminosity equals ~1x10^44 erg/s, which, along with the observed softness of the spectrum,
implies a probable association of the source with a Tidal Disruption Event.
The detection by SRG/eROSITA precedes an alert issued by Zwicky Transient Facility
on 2019-12-29 ( https://mars.lco.global/145673926/ ), which indicates a jump of -1.07 mag in r band
(and 0.38 mag in g band) centered on this galaxy, corresponding to optical luminosity ~3x10^42 erg/s
i.e. a few percent of the observed X-ray luminosity. The decay of the excess optical emission has been traced till 2020-01-08.
On 2020-02-05 (i.e. more than a month later), Swift/XRT serendipitously detected bright X-ray emission from this galaxy
at a similar level (ATel #13464), supposing the long-term nature of the observed phenomenon.
Somewhat harder spectrum observed by Swift/XRT might indicate spectral evolution of the source's emission,
in full agreement with the expectation for the TDE scenario.
