Tidal disruption event SRGeJ213527.3-181634/ZTF20abgbdpr
ATel #14246; M. Gilfanov (IKI, MPA), S. Sazonov (IKI), R. Sunyaev (IKI, MPA), P. Medvedev (IKI), G. Khorunzhev (IKI), A. Semena (IKI), Yuhan Yao (Caltech), S. R. Kulkarni (Caltech), Suvi Gezari (STScI) & Sjoert van Velzen (Leiden)
on 6 Dec 2020; 08:21 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Pavel Medvedev (tomedvedev@iki.rssi.ru)
Subjects: Radio, Optical, X-ray, Tidal Disruption Event
Referred to by ATel #: 14248
On November 9, 2020, in the course of the second all-sky survey, eROSITA telescope aboard SRG observatory discovered a soft X-ray transient source at RA=323.8640 Dec=-18.2762 with the error radius of 4 arcsec. Its X-ray spectrum can be described with a black body model with the temperature of ~70 eV and 0.3-2.0 keV flux of ~1.7e-12 erg/s/cm2. No X-ray emission from this region was detected in the first all sky survey on May 8-9, 2020 with the upper limit about ten times deeper than the November 9 level.
The X-ray source was identified with ZTF20abgbdpr (at 21:35:27.25, -18:16:35.5) which is coincident with the center of a quiescent galaxy. The optical transient was first detected by ZTF on June 18, 2020. ZTF202bgdpr was observed on November 20, 2020 with KeckI/LRIS (PI: M. Kasliwal) and the data reduced by Kishalay De. The spectrum reveals broad H-alpha and a broad complex of emission around HeII 4686A and a host galaxy, all at redshift of 0.0942. The strong Balmer absorption is suggestive of a post-starburst galaxy. We triggered Swift TOO observations and detected a soft X-ray source, consistent with the position of ZTF20abgbdpr, with flux of 1.3e-12 erg/cm^2/s (0.3-2 keV), assuming Galactic NH.
Taking the totality of the X-ray and optical data together we conclude that SRG/ZTF transient is a Tidal Disruption Event (TDE). At the measured redshift, the eROSITA X-ray luminosity is 3.8e43 erg/s (absorbed, 0.3-2.0 keV). Additional observations, particularly at radio wavelengths, would be helpful.
