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

Pan-Starrs, Asas-Sn, Atlas, T. W.S. Holoien, M. E. Huber, B. J. Shappee, M. Eracleous, K. Auchettl, 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. DongG. Hallinan, N. A. Reddy, R. L. Sanders, 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, B. Stalder, J. L. Tonry, H. Weiland

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We present the discovery of PS18kh, a tidal disruption event discovered at the center of SDSS J075654.53+341543.6 (d ≃ 322 Mpc) by the Pan-STARRS Survey for Transients. Our data set includes pre-discovery survey data from Pan-STARRS, the All-sky Automated Survey for Supernovae, and the Asteroid Terrestrial-impact Last Alert System as well as high-cadence, multiwavelength 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 ≃ 12,000 K to T ≃ 25,000 K and it peaked at a luminosity of L ≃ 8.8 × 1043 erg s-1. PS18kh radiated E = (3.45 ± 0.22) × 1050 erg over the period of observation, with (1.42 ± 0.20) × 1050 erg being released during the rise to peak. Spectra of PS18kh show a changing, boxy/double-peaked Hα emission feature, which becomes more prominent over time. We use models of non-axisymmetric accretion disks to describe the profile of the Hα 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 ∼ 60r g to an outer radius of r out ∼ 1400r 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.

Original languageEnglish
Article number120
Number of pages21
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 01 Aug 2019


  • accretion, accretion disks
  • black hole physics
  • galaxies: nuclei

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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