ASASSN-20hx is a Hard Tidal Disruption Event Candidate
ATel #13895; Dacheng Lin (University of New Hampshire)
on 25 Jul 2020; 04:49 UT
Credential Certification: Dacheng Lin (dacheng.lin@gmail.com)
Subjects: Optical, Ultra-Violet, X-ray, Transient, Tidal Disruption Event
ASASSN-20hx (AT 2020ohl) was discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN; Shappee et al. 2014, Kochanek et al. 2017) on UT 2020-07-10.34 (ATel #13891). Hinkle et al (ATel #13893) classified it as a tidal disruption event based on the location in the center of the host galaxy NGC 6297 at z = 0.01671, a slow rise in ASAS-SN photometry, luminous UV and X-ray emission, roughly constant blue colors, and the detection of a blue spectrum with broad emission lines.
We analyzed the X-ray spectra from the first five Swift observations taken for this event and found them to be hard and can be well fitted with a powerlaw with photon index around 2.2-2.6 and 0.3-10 keV absorbed flux about 2 to 3e-12 erg/s/cm^2 (luminosity about 1.5e42 erg/s). No local column density was required in the fits. The spectra cannot be fitted well with a single-temperature blackbody or a disk blackbody with clear fit residuals.
Therefore this is one of the very few tidal disruption events with hard powerlaw X-ray spectra. We encourage further follow-up of this source.
