TY - JOUR
T1 - K2 Observations of SN 2018oh Reveal a Two-component Rising Light Curve for a Type Ia Supernova
AU - Konkoly
AU - Epessto
AU - University of Arizona
AU - K2 Mission Team
AU - Kegs
AU - Kepler Spacecraft Team
AU - Pan-Starrs
AU - Decam
AU - Asas-Sn
AU - Ptss/tnts
AU - Las Cumbres Observatory
AU - Atlas
AU - Dimitriadis, G.
AU - Foley, R. J.
AU - Rest, A.
AU - Kasen, D.
AU - Piro, A. L.
AU - Polin, A.
AU - Jones, D. O.
AU - Villar, A.
AU - Narayan, G.
AU - Coulter, D. A.
AU - Kilpatrick, C. D.
AU - Pan, Y. C.
AU - Rojas-Bravo, C.
AU - Fox, O. D.
AU - Jha, S. W.
AU - Nugent, P. E.
AU - Riess, A. G.
AU - Scolnic, D.
AU - Drout, M. R.
AU - Barentsen, G.
AU - Hanley, M.
AU - Moffatt, J.
AU - Flynn, S.
AU - Elsaesser, B.
AU - Chambers, K. C.
AU - Smartt, S. J.
AU - Smith, K. W.
AU - Shields, J.
AU - Li, W.
AU - Wang, X.
AU - Zhang, J.
AU - Lin, H.
AU - Zhao, X.
AU - Zhang, X.
AU - Zhang, K.
AU - Zhang, T.
AU - Wang, L.
AU - Zhang, J.
AU - Li, L.
AU - Chen, Z.
AU - Xiang, D.
AU - Wang, L.
AU - Huang, F.
AU - Li, X.
AU - Valenti, S.
AU - Denneau, L.
AU - Pál, A.
AU - Williams, S. C.
AU - Inserra, C.
AU - Smith, N.
PY - 2019/1/1
Y1 - 2019/1/1
N2 - We present an exquisite 30 minute 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 Panoramic Survey Telescope (Pan-STARRS1) and Rapid Response System 1 and Cerro Tololo Inter-American Observatory 4 m Dark Energy Camera (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 supernovae (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 ± 0.04 days after explosion, has a FWHM of 3.12 ± 0.04 days, a blackbody temperature of K, a peak luminosity of , and a total integrated energy of . 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 ∼ 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.
AB - We present an exquisite 30 minute 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 Panoramic Survey Telescope (Pan-STARRS1) and Rapid Response System 1 and Cerro Tololo Inter-American Observatory 4 m Dark Energy Camera (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 supernovae (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 ± 0.04 days after explosion, has a FWHM of 3.12 ± 0.04 days, a blackbody temperature of K, a peak luminosity of , and a total integrated energy of . 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 ∼ 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.
KW - supernovae: general
KW - supernovae: individual (SN 2018oh)
UR - http://www.scopus.com/inward/record.url?scp=85059854261&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/aaedb0
DO - 10.3847/2041-8213/aaedb0
M3 - Article
AN - SCOPUS:85059854261
VL - 870
JO - The Astrophysical Journal Letters
JF - The Astrophysical Journal Letters
SN - 2041-8213
IS - 1
M1 - L1
ER -