ZTF Discovery of a Tidal Disruption Event at z=0.051
ATel #12035; S. Gezari (UMd, JSI), S. van Velzen (UMd), S. B. Cenko (NASA/Goddard, JSI), M. Graham (Caltech), N. Blagorodnova (Caltech), T. Hung (UCSC), L. Yan (Caltech), S. Kulkarni (Caltech) on behalf of the Zwicky Transient Facility collaboration
on 13 Sep 2018; 13:59 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Suvi Gezari (suvi@astro.umd.edu)
Subjects: Optical, Ultra-Violet, Tidal Disruption Event
The Zwicky Transient Facility (ZTF; ATel #11266) reports the discovery of a tidal disruption event in a red star-forming galaxy (SDSSJ081526.63+453532.0) at z=0.051. ZTF18aahqkbt (AT2018bsi) is a nuclear (offset < 0.1 arcsec) transient located at:
08:15:26.62 +45:35:31.9 (J2000)
123.860919 +45.592208 (J2000)
The source was first detected by the ZTF Survey on UT 2018 April 09 with r=18.19 +/- 0.03 mag. We triggered the Spectral Energy Distribution Machine (SEDM) (range 350-950nm, spectral resolution R~100) mounted on the Palomar 60-in (P60) telescope (Blagorodnova et al. 2018, PASP, 130, 5003) on UT 2018 April 18 which detected a blue continuum and a broad H and He II 4686 lines, which were confirmed with our follow-up R~1000 spectra with the Discovery Channel Telescope DeVeny spectrograph on UT 2018 May 13. We triggered Swift observations taken on 2018 June 02 which detected an AB magnitude of uvw2=17.90 +/- 0.05 mag, significantly brighter than the archival AIS GALEX magnitude of NUV=19.22 mag (Bianchi et al. 2011). The source then went behind the Sun. We recently triggered a Swift observation taken on UT 2018 Sep 05 that shows that the source has faded in the UV to uvw2 = 19.30 +/- 0.10 mag as expected for a UV transient. The broad He II lines and UV-bright nature of the transient are both consistent with the classification of ZTF18aahqkbt as a tidal disruption event (nicknamed ZTF-JonSnow). We have triggered HST/STIS UV spectroscopy and XMM X-ray imaging observations of the TDE to be observed between September 24th and October 5th. Follow-up spectra are encouraged.
ZTF is a project led by PI S. R. Kulkarni at Caltech (see ATEL #11266), and includes IPAC; WIS, Israel; OKC, Sweden; JSI/UMd, USA; UW,USA; DESY, Germany; NRC, Taiwan; UW Milwaukee, USA and LANL USA. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. Alert
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