PS18kh: A New Tidal Disruption Event with a Non-Axisymmetric Accretion Disk

T. W. -S. Holoien; M. E. Huber; B. J. Shappee; M. Eracleous; K. Auchettl; J. S. Brown; M. A. Tucker; K. C. Chambers; C. S. Kochanek; K. Z. Stanek; A. Rest; D. Bersier; R. S. Post; G. Aldering; K. A. Ponder; J. D. Simon; E. Kankare; D. Dong.; G. Hallinan; N. A. Reddy; R. L. Sanders; M. W. Topping; J. Bulger; T. B. Lowe; E. A. Magnier; A. S. B. Schultz; C. Z. Waters; M. Willman; D. Wright; D. R. Young; Subo Dong; J. L. Prieto; Todd A. Thompson; L. Denneau; H. Flewelling; A. N. Heinze; S. J. Smartt; K. W. Smith; B. Stalder; J. L. Tonry; H. Weiland

doi:10.3847/1538-4357/ab2ae1

paper

PS18kh: A New Tidal Disruption Event with a Non-Axisymmetric Accretion Disk

arXiv:1808.02890 · doi:10.3847/1538-4357/ab2ae1

Abstract

We present the discovery of PS18kh, a tidal disruption event (TDE) discovered at the center of SDSS J075654.53+341543.6 ( $d ≃ 322$ Mpc) by the Pan-STARRS Survey for Transients. Our dataset includes pre-discovery survey data from Pan-STARRS, the All-Sky Automated Survey for Supernovae (ASAS-SN), and the Asteroid Terrestrial-impact Last Alert System (ATLAS) as well as high-cadence, multi-wavelength follow-up data from ground-based telescopes and Swift, spanning from 56 days before peak light until 75 days after. The optical/UV emission from PS18kh is well-fit as a blackbody with temperatures ranging from $T ≃ 12000$ K to $T ≃ 25000$ K and it peaked at a luminosity of $L ≃ 8.8 \times 1 0^{43}$ ergs s $^{- 1}$ . PS18kh radiated $E = (3.45 \pm 0.22) \times 1 0^{50}$ ergs over the period of observation, with $(1.42 \pm 0.20) \times 1 0^{50}$ ergs being released during the rise to peak. Spectra of PS18kh show a changing, boxy/double-peaked H $α$ emission feature, which becomes more prominent over time. We use models of non-axisymmetric accretion disks to describe the profile of the H $α$ line and its evolution. We find that at early times the high accretion rate leads the disk to emit a wind which modifies the shape of the line profile and makes it bell-shaped. At late times, the wind becomes optically thin, allowing the non-axisymmetric perturbations to show up in the line profile. The line-emitting portion of the disk extends from $r_{in} \sim 60 r_{g}$ to an outer radius of $r_{out} \sim 1400 r_{g}$ and the perturbations can be represented either as an eccentricity in the outer rings of the disk or as a spiral arm in the inner disk.

arXiv comment27 pages, 13 figures, 8 tables. Updated to reflect changes made in the published version. A table containing the host-subtracted photometry presented in this manuscript is included in machine-readable format as an ancillary file

PS18kh: A New Tidal Disruption Event with a Non-Axisymmetric Accretion Disk

Abstract

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