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Title: TESS shines light on the origin of the ambiguous nuclear transient ASASSN-18el
ABSTRACT We analyse high-cadence data from the Transiting Exoplanet Survey Satellite (TESS) of the ambiguous nuclear transient (ANT) ASASSN-18el. The optical changing-look phenomenon in ASASSN-18el has been argued to be due to either a drastic change in the accretion rate of the existing active galactic nucleus (AGN) or the result of a tidal disruption event (TDE). Throughout the TESS observations, short-time-scale stochastic variability is seen, consistent with an AGN. We are able to fit the TESS light curve with a damped-random-walk (DRW) model and recover a rest-frame variability amplitude of $$\hat{\sigma } = 0.93 \pm 0.02$$ mJy and a rest-frame time-scale of $$\tau _{DRW} = 20^{+15}_{-6}$$ d. We find that the estimated τDRW for ASASSN-18el is broadly consistent with an apparent relationship between the DRW time-scale and central supermassive black hole mass. The large-amplitude stochastic variability of ASASSN-18el, particularly during late stages of the flare, suggests that the origin of this ANT is likely due to extreme AGN activity rather than a TDE.  more » « less
Award ID(s):
1908570
PAR ID:
10431057
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Monthly Notices of the Royal Astronomical Society
Volume:
521
Issue:
3
ISSN:
0035-8711
Page Range / eLocation ID:
3517 to 3526
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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