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K2 Observations of SN 2018oh Reveal a Two-Component Rising Light Curve for a Type Ia Supernova

Research output: Contribution to journalJournal articlepeer-review

  • G. Dimitriadis
  • R. J. Foley
  • A. Rest
  • D. Kasen
  • A. L. Piro
  • A. Polin
  • D. O. Jones
  • A. Villar
  • G. Narayan
  • D. A. Coulter
  • C. D. Kilpatrick
  • Y.-C. Pan
  • C. Rojas-Bravo
  • O. D. Fox
  • S. W. Jha
  • P. E. Nugent
  • A. G. Riess
  • D. Scolnic
  • M. R. Drout
  • G. Barentsen
  • J. Dotson
  • M. Gully-Santiago
  • C. Hedges
  • A. M. Cody
  • T. Barclay
  • S. Howell
  • P. Garnavich
  • B. E. Tucker
  • E. Shaya
  • R. Mushotzky
  • R. P. Olling
  • S. Margheim
  • A. Zenteno
  • J. Coughlin
  • J. E. Van Cleve
  • J. Vinicius de Miranda Cardoso
  • K. A. Larson
  • K. M. McCalmont-Everton
  • C. A. Peterson
  • S. E. Ross
  • L. H. Reedy
  • D. Osborne
  • C. McGinn
  • L. Kohnert
  • L. Migliorini
  • A. Wheaton
  • B. Spencer
  • C. Labonde
  • G. Castillo
  • G. Beerman
  • K. Steward
  • M. Hanley
  • R. Larsen
  • R. Gangopadhyay
  • R. Kloetzel
  • T. Weschler
  • V. Nystrom
  • J. Moffatt
  • M. Redick
  • K. Griest
  • M. Packard
  • M. Muszynski
  • J. Kampmeier
  • R. Bjella
  • S. Flynn
  • B. Elsaesser
  • K. C. Chambers
  • H. A. Flewelling
  • M. E. Huber
  • E. A. Magnier
  • C. Z. Waters
  • A. S. B. Schultz
  • J. Bulger
  • T. B. Lowe
  • M. Willman
  • S. J. Smartt
  • K. W. Smith
  • S. Points
  • G. M. Strampelli
  • J. Brimacombe
  • P. Chen
  • J. A. Munoz
  • R. L. Mutel
  • J. Shields
  • P. J. Vallely
  • S., Jr Villanueva
  • W. Li
  • X. Wang
  • J. Zhang
  • H. Lin
  • J. Mo
  • X. Zhao
  • H. Sai
  • X. Zhang
  • K. Zhang
  • T. Zhang
  • L. Wang
  • J. Zhang
  • E. Baron
  • J. M. DerKacy
  • L. Li
  • Z. Chen
  • D. Xiang
  • L. Rui
  • L. Wang
  • F. Huang
  • X. Li
  • G. Hosseinzadeh
  • D. A. Howell
  • I. Arcavi
  • D. Hiramatsu
  • J. Burke
  • S. Valenti
  • J. L. Tonry
  • L. Denneau
  • A. N. Heinze
  • H. Weiland
  • B. Stalder
  • J. Vinko
  • K. Sarneczky
  • A. Pa
  • A. Bodi
  • Zs. Bognar
  • B. Csak
  • B. Cseh
  • G. Csornyei
  • O. Hanyecz
  • B. Ignacz
  • Cs. Kalup
  • R. Konyves-Toth
  • L. Kriskovics
  • A. Ordasi
  • I. Rajmon
  • A. Sodor
  • R. Szabo
  • R. Szakats
  • G. Zsidi
  • J. Nordin
  • R. Cartier
  • C. Frohmaier
  • L. Galbany
  • C. P. Gutierrez
  • C. Inserra
  • M. Smith
  • D. J. Sand
  • J. E. Andrews
  • N. Smith
  • C. Bilinski
Article numberL1
<mark>Journal publication date</mark>1/01/2019
<mark>Journal</mark>Astrophysical Journal Letters
Number of pages16
Publication StatusPublished
Early online date28/12/18
<mark>Original language</mark>English


We present an exquisite, 30-min cadence Kepler (K2) light curve of the Type Ia supernova (SN Ia) 2018oh (ASASSN-18bt), starting weeks before explosion, covering the moment of explosion and the subsequent rise, and continuing past peak brightness. These data are supplemented by multi-color Pan-STARRS1 and CTIO 4-m DECam observations obtained within hours of explosion. The K2 light curve has an unusual two-component shape, where the flux rises with a steep linear gradient for the first few days, followed by a quadratic rise as seen for typical SNe Ia. This "flux excess" relative to canonical SN Ia behavior is confirmed in our $i$-band light curve, and furthermore, SN 2018oh is especially blue during the early epochs. The flux excess peaks 2.14$\pm0.04$ days after explosion, has a FWHM of 3.12$\pm0.04$ days, a blackbody temperature of $T=17,500^{+11,500}_{-9,000}$ K, a peak luminosity of $4.3\pm0.2\times10^{37}\,{\rm erg\,s^{-1}}$, and a total integrated energy of $1.27\pm0.01\times10^{43}\,{\rm erg}$. We compare SN 2018oh to several models that may provide additional heating at early times, including collision with a companion and a shallow concentration of radioactive nickel. While all of these models generally reproduce the early K2 light curve shape, we slightly favor a companion interaction, at a distance of $\sim$$2\times10^{12}\,{\rm cm}$ based on our early color measurements, although the exact distance depends on the uncertain viewing angle. Additional confirmation of a companion interaction in future modeling and observations of SN 2018oh would provide strong support for a single-degenerate progenitor system.

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