Bright X-ray source SRGet J134954.70+432859.5 in the direction of galaxy SDSS J134954.68+432856.0
ATel #13499; I. Khabibullin, P. Medvedev, E. Churazov, M. Gilfanov, S. Sazonov, R. Sunyaev, R. Burenin, M. Pavlinsky on behalf of the Russian SRG/eROSITA Consortium and the SRG/ART-XC team
on 18 Feb 2020; 18:28 UT
Credential Certification: Ildar Khabibullin (khabibullin@iki.rssi.ru)
Subjects: X-ray, AGN, Transient, Tidal Disruption Event
Referred to by ATel #: 13513
We report on SRG/eROSITA detection of a bright (Fx[0.3-3 keV]=2e-12 erg/s/cm^2) X-ray source SRGet J134954.70+432859.5 (RA,Dec=207.477903,+43.483201)
centered on galaxy SDSS J134954.68+432856.0 (with better than 10 arcsec accuracy),
which previously demonstrated no signatures of a bright active nucleus neither in X-rays (according to the ROSAT All-Sky Survey data) nor in the optical spectra (provided by SDSS).
In the course of the all-sky survey, SRG/eROSITA observed the source for the first time on 2019-12-12 and then scanned it 7 more times with an interval of 4 hours (each time with exposure of ~40 seconds). The spectral shape of the integrated emission is approximately described by an absorbed power-law with Gamma=2.0+/-0.2 and N_H~1.4e20 cm^{-2} (Galactic N_H=1.1e20 cm^{-2}).
The ART-XC telescope on board SRG did not detect any signal from this source during the same period,
with a 2-sigma upper limit of 3e-12 erg/s/cm^2 in the 4-12 keV energy band.
This non-detection rules out any significant hard X-ray excess on top of the power-law spectrum measured by SRG/eROSITA.
At the redshift of the galaxy, z=0.045, the measured X-ray flux corresponds to luminosity Lx(0.3-3 keV)~10^43 erg/s. The inferred luminosity suggests that strongly enhanced level of the SMBH activity might have switched on, potentially originating from a Tidal Disruption Event. We encourage sensitive follow-up observations at all wavelengths to help clarifying the nature of this source.
