ZTF Detection of Optical Transient Coincident with SRG/eROSITA X-ray TDE candidate
ATel #13513; S. Gezari (UMd), C. Ward (UMd), D. Goldstein (Caltech), M. J. Graham (Caltech), S. van Velzen (UMd), S. B. Cenko (NASA/Goddard), and S. Kulkarni (Caltech) on behalf of the ZTF Collaboration
on 22 Feb 2020; 18:42 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Suvi Gezari (suvi@astro.umd.edu)
Subjects: Optical, Request for Observations, AGN, Black Hole, Transient, Tidal Disruption Event
ATel #13499 reported the discovery by SRG/eROSITA of an X-ray TDE candidate, SRGet J134954.70+432859.5, on 2019 Dec 12 centered on the galaxy SDSS J134954.68+432856.0. Here we report the serendipitous detection of an optical transient, ZUDS20dkxcy, within 0.75 arcsec of the host galaxy nucleus in subtracted 7-day coadds from the ZTF Survey. The coadds were produced as a part of the ZTF Uniform Depth Survey (ZUDS; Goldstein et al. 2020, in prep), a ZTF partnership experiment. They typically contained 7 g (30s), r (30s), or i-band (90s) exposures, reach a limiting magnitude of 21.5 in all three filters. ZUDS20dkxcy was detected with g = 20.2 mag on 2019 Dec 12, fading monotonically to g = 21.5 mag on 2020 Feb 18. We can constrain the onset of the transient to be after the the last non-detection in the g-band on 2019 Nov 17. We detect no previous optical variability in the galaxy from over 1 year of 3-day cadence ZTF survey observations. At the redshift of the host galaxy of z=0.045, the optical flare absolute magnitude is only M_g=-16.3 mag, which is faint compared to optically selected tidal disruption events (typically with M_g ~ -19 to -20 mag), but this could be a result of selecting the TDE candidate in the X-rays. Optical spectroscopy is encouraged to characterize the nature of this X-ray and optical transient.
