The Tidal Disruption Event AT 2018hyz II: Light-curve modelling of a partially disrupted star
ABSTRACT AT 2018hyz (= ASASSN-18zj) is a tidal disruption event (TDE) located in the nucleus of a quiescent E+A galaxy at a redshift of z = 0.04573, first detected by the All-Sky Automated Survey for Supernovae (ASAS-SN). We present optical+UV photometry of the transient, as well as an X-ray spectrum and radio upper limits. The bolometric light curve of AT 2018hyz is comparable to other known TDEs and declines at a rate consistent with a t−5/3 at early times, emitting a total radiated energy of E = 9 × 1050 erg. An excess bump appears in the UV light curve about 50 d after bolometric peak, followed by a flattening beyond 250 d. We detect a constant X-ray source present for at least 86 d. The X-ray spectrum shows a total unabsorbed flux of ∼4 × 10−14 erg cm−2 s−1 and is best fit by a blackbody plus power-law model with a photon index of Γ = 0.8. A thermal X-ray model is unable to account for photons >1 keV, while a radio non-detection favours inverse-Compton scattering rather than a jet for the non-thermal component. We model the optical and UV light curves using the Modular Open-Source Fitter for Transients (MOSFiT) and find a best fit for a black hole of 5.2 × 106 M⊙ disrupting a 0.1 M⊙ star; the more »
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Award ID(s):
Publication Date:
NSF-PAR ID:
10187868
Journal Name:
Monthly Notices of the Royal Astronomical Society
Volume:
497
Issue:
2
Page Range or eLocation-ID:
1925 to 1934
ISSN:
0035-8711
2. ABSTRACT The ultraviolet (UV) and near-infrared (NIR) photometric and optical spectroscopic observations of SN 2020acat covering ∼250 d after explosion are presented here. Using the fast rising photometric observations, spanning from the UV to NIR wavelengths, a pseudo-bolometric light curve was constructed and compared to several other well-observed Type IIb supernovae (SNe IIb). SN 2020acat displayed a very short rise time reaching a peak luminosity of $\mathrm{{\rm Log}_{10}}(L) = 42.49 \pm 0.17 \, \mathrm{erg \, s^{-1}}$ in only ∼14.6 ± 0.3 d. From modelling of the pseudo-bolometric light curve, we estimated a total mass of 56Ni synthesized by SN 2020acat of MNi = 0.13 ± 0.03 M⊙, with an ejecta mass ofmore »