SN 2018agk: A Prototypical Type Ia Supernova with a Smooth Power-law Rise in Kepler (K2)

Qinan Wang, Armin Rest, Yossef Zenati*, Ryan Ridden-Harper, Georgios Dimitriadis, Gautham Narayan, V. Ashley Villar, Mark R. Magee, Ryan J. Foley, Edward J. Shaya, Peter Garnavich, Lifan Wang, Lei Hu, Attila Bódi, Patrick Armstrong, Katie Auchettl, Thomas Barclay, Geert Barentsen, Zsófia Bognár, Joseph BrimacombeJoanna Bulger, Jamison Burke, Peter Challis, Kenneth Chambers, David A. Coulter, Géza Csörnyei, Borbála Cseh, Maxime Deckers, Jessie L. Dotson, Lluís Galbany, Santiago González-Gaitán, Mariusz Gromadzki, Michael Gully-Santiago, Ottó Hanyecz, Christina Hedges, Daichi Hiramatsu, Griffin Hosseinzadeh, D. Andrew Howell, Steve B. Howell, Mark E. Huber, Saurabh W. Jha, David O. Jones*, Réka Könyves-Tóth, Csilla Kalup, Charles D. Kilpatrick, Levente Kriskovics, Wenxiong Li, Thomas B. Lowe, Steven Margheim, Curtis McCully, Ayan Mitra, Jose A. Muñoz, Matt Nicholl, Jakob Nordin, András Pál, Yen Chen Pan, Anthony L. Piro, Sofia Rest, João Rino-Silvestre, César Rojas-Bravo, Krisztián Sárneczky, Matthew R. Siebert, Stephen J. Smartt, Ken Smith, Ádám Sódor, Maximilian D. Stritzinger, Róbert Szabó, Róbert Szakáts, Brad E. Tucker, József Vinkó, Xiaofeng Wang, J. Craig Wheeler, David R. Young, Alfredo Zenteno, Kai Cheng Zhang, Gabriella Zsidi

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    11 Citations (Scopus)


    We present the 30 minutes cadence Kepler/K2 light curve of the Type Ia supernova (SN Ia) SN 2018agk, covering approximately one week before explosion, the full rise phase, and the decline until 40 days after peak. We additionally present ground-based observations in multiple bands within the same time range, including the 1 day cadence DECam observations within the first ∼5 days after the first light. The Kepler early light curve is fully consistent with a single power-law rise, without evidence of any bump feature. We compare SN 2018agk with a sample of other SNe Ia without early excess flux from the literature. We find that SNe Ia without excess flux have slowly evolving early colors in a narrow range (g − i ≈ −0.20 ± 0.20 mag) within the first ∼10 days. On the other hand, among SNe Ia detected with excess, SN 2017cbv and SN 2018oh tend to be bluer, while iPTF16abc’s evolution is similar to normal SNe Ia without excess in g − i. We further compare the Kepler light curve of SN 2018agk with companion-interaction models, and rule out the existence of a typical nondegenerate companion undergoing Roche lobe overflow at viewing angles smaller than 45°.

    Original languageEnglish
    Article number167
    JournalAstrophysical Journal
    Issue number2
    Publication statusPublished - 20 Dec 2021


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