Two Nuclear Transients from ZTF Classified as Tidal Disruption Events
ATel #13944; Suvi Gezari (UMd), Dan Perley (LJMU), Jesper Sollerman (OKC), on behalf of the ZTF Collaboration
on 14 Aug 2020; 15:47 UT
Credential Certification: Suvi Gezari (suvi@astro.umd.edu)
Subjects: Optical, Ultra-Violet, Transient, Tidal Disruption Event
We report two nuclear transients from the ZTF MSIP Northern Sky Survey that we classify as tidal disruption events (TDEs) by their blue optical colors, bright UV flux measured by the Neil Gehrels Swift Telescope, and follow-up optical spectra.
ZTF20abfcszi/AT2020mot was first detected by ZTF on 2020 Jun 14, and first reported to TNS from the ZTF public alert stream by ALeRCE on 2020 Jun 14, and has slowly risen to g=18.25 mag on 2020 Aug 12 with a constant blue color (g-r ~ - 0.15 mag). The transient is located in the nucleus of galaxy PS1 J003113.54+850031.8. We obtained several follow-up spectra, including a medium resolution spectrum with the NOT+ALFOSC telescope on 2020 Jul 31, that shows a strong, broad He II 4686 line and broad Balmer lines, including stellar absorption features from the host galaxy at z=0.070. Our Swift follow-up observations on 2020 Aug 14 measure a bright UV flux of uvw2=17.82 mag. We detect no X-ray source in the XRT image. We thus classify the transient as a TDE-Bowen at z=0.070. This classification is in agreement with the classification report posted by Hosseinzadeh et al. on 2020 Aug 13 (TNSCR2478). We have triggered further Swift monitoring.
ZTF20abjwvae/AT2020opy was first detected by ZTF on 2020 Jul 08, and first reported to TNS from the ZTF public alert stream by SGLF on 2020 Jul 12, and slowly rose to a peak of g=18.9 on 2020 Aug 02 with a constant blue color (g-r ~ -0.25 mag). The transient is located in the nucleus of galaxy SDSS J155625.72+232220.6. We obtained a follow-up spectrum with the Palomar 60in SED Machine, which measures a featureless blue continuum. Our Swift follow-up observations on 2020 Aug 09 measure a bright UV flux of uvw2=18.59 mag. We detect no X-ray source in the XRT image. We thus classify the transient as a TDE at an unknown redshift. Further follow-up medium resolution spectroscopy is encouraged. We have triggered further Swift monitoring.
