The Exotic Type Ic Broad-lined Supernova SN 2018gep: Blurring the Line between Supernovae and Fast Optical Transients

Research output: Contribution to journalJournal articleResearchpeer-review

  • T. A. Pritchard
  • Katarzyna Bensch
  • Maryam Modjaz
  • Marc Williamson
  • Christina C. Thone
  • J. Vinko
  • Federica B. Bianco
  • K. Azalee Bostroem
  • Jamison Burke
  • Ruben Garcia-Benito
  • L. Galbany
  • Daichi Hiramatsu
  • D. Andrew Howell
  • D. Alexander Kann
  • Curtis McCully
  • Craig Pellegrino
  • Antonio de Ugarte Postigo
  • Stefano Valenti
  • Xiaofeng Wang
  • J. C. Wheeler
  • Danfeng Xiang
  • K. Sarneczky
  • A. Bodi
  • B. Cseh
  • D. Tarczay-Nehez
  • L. Kriskovics
  • A. Ordasi
  • A. Pal
  • R. Szakats
  • K. Vida

In the last decade a number of rapidly evolving transients have been discovered that are not easily explained by traditional supernova models. We present optical and UV data on one such object, SN 2018gep, that displayed a fast rise with a mostly featureless blue continuum around peak, and evolved to develop broad features typical of an SN Ic-bl while retaining significant amounts of blue flux throughout its observations. This blue excess is most evident in its near-UV flux, which is over 4 mag brighter than other stripped-envelope supernovae, and is still visible in optical g-r colors. Its fast rise time of t (rise,V ) = 5.6 +/- 0.5 days puts it squarely in the emerging class of Fast Evolving Luminous Transients, or Fast Blue Optical Transients. With a peak absolute magnitude of M ( v ) = -19.53 +/- 0.23 mag it is on the extreme end of both the rise time and peak magnitude distribution for SNe Ic-bl. These observations are consistent with a simple SN Ic-bl model that has an additional form of energy injection at early times that drives the observed rapid, blue rise. We show that SN 2018gep and the literature SN iPTF16asu have similar photometric and spectroscopic properties and that they overall share many similarities with both SNe Ic-bl and Fast Evolving Transients. Based on our SN 2018gep host galaxy data we derive a number of properties, and we show that the derived host galaxy properties for both SN 2018gep and iPTF16asu are consistent with the SNe Ic-bl and gamma-ray burst/supernova sample while being on the extreme edge of the observed Fast Evolving Transient sample.

Original languageEnglish
Article number121
JournalAstrophysical Journal
Volume915
Issue number2
Number of pages16
ISSN0004-637X
DOIs
Publication statusPublished - 15 Jul 2021

    Research areas

  • INTEGRAL FIELD SPECTROSCOPY, MASS-METALLICITY RELATION, POTSDAM MULTIAPERTURE SPECTROPHOTOMETER, RAPIDLY EVOLVING TRANSIENTS, SUPERLUMINOUS SUPERNOVAE, STRIPPED-ENVELOPE, HOST GALAXIES, LIGHT CURVES, X-RAY, SHOCK BREAKOUT

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