Wang, QinanRest, A.Zenati, YRidden-Harper, RDimitriadis, G.Narayan, GVillar, Victoria AshleyMagee, Mark R.Foley, Ryan JShaya, E. J.Tucker, Brad2024-03-212024-03-211538-4357http://hdl.handle.net/1885/316213We 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 similar to 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 approximate to -0.20 +/- 0.20 mag) within the first similar to 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 degrees.J.V. and the Konkoly team have been supported by the project “Transient Astrophysical Objects” GINOP 2.3.2-15- 2016-00033 of the National Research, Development and Innovation Office (NKFIH), Hungary, funded by the European Union. The LCOGT team is supported by NASA grant 80NSSC19 K0119 and NSF grants AST-1911225 and AST-1911151. Pan-STARRS is a project of the Institute for Astronomy of the University of Hawai’i, and is supported by the NASA SSO Near Earth Observation Program under grants 80NSSC 18K0971, NNX14AM74G, NNX12AR65G, NNX13AQ47G, NNX08AR22G, and by the State of Hawai’i. This paper uses data obtained with ANDICAM mounted to the 1.3 m telescope at the Cerro Tololo Inter-American Observatory (CTIO) and operated by the SMARTS Consortium under program NOAO-18A-0047 (PI: Galbany). QUB acknowledges funding from STFC grants ST/S006109/1, ST/P000312/1 and ST/T000198/1. This project has been supported by the Lendület Program of the Hungarian Academy of Sciences, project No. LP2018-7/2020. Research infrastructure was provided by the Hungarian Academy of Sciences. This work was partially supported by the Center for Astrophysical Surveys (CAPS) at the National Center for Supercomputing Applications (NCSA), University of Illinois Urbana-Champaign. Parts of this research were supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project CE170100013. This research has made use of the SVO Filter Profile Service (http://svo2.cab.inta-csic.es/theory/fps/) supported from the Spanish MINECO through grant AYA2017-84089. Q.W. acknowledges financial support provided by the STScI Director’s Discretionary Fund. Y.Z. thanks Alexey Bobrick and Naveh Levanon for valuable discussions. M.R.M. is funded by the EU H2020 ERC grant no. 758638. D.A.C. acknowledges support from the National Science Foundation Graduate Research Fellowship under grant DGE1339067. L.G. acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2019 Ramón y Cajal program RYC2019-027683 and from the Spanish MICIU project PID2020-115253 GA-I00. D.O.J. acknowledges support provided by NASA Hubble Fellowship grant HST-HF2-51462.001, which is awarded by the Space Telescope Science Institute, operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. P.G. and P.C. acknowledge the support of NASA grant NAS5- 26555 from program HST GO-15274. We also thank R. Kirshner for his support with this work. L.W. is supported by NSF grant AST-1817099 and NASA grant and NASA grant 80NSSC20K0538. L.K. acknowledges the financial support of the Hungarian National Research, Development and Innovation Office grant NKFIH PD-134784. L.K. is a Bolyai János Research Fellow. M.G. is supported by the EU Horizon 2020 research and innovation program under grant agreement No 101004719. J.B. would like to thank Lisa Rush, Piper English, and Andre Van Zundert for their help in data collection. S.G.G. acknowledges support by FCT under Project CRISP PTDC/FIS-AST-31546/2017 and UIDB/00099/2020. J.R.S. is funded by FCT (PD/BD/150487/2019), via the IDPASC PhD program, and by the CRISP project (PTDC/FISAST/31546/2017). B.E.T. acknowledge parts of this research was carried out on the traditional lands of the Ngunnawal people. We pay our respects to their elders past, present, and emerging. B.E.T. and his group were supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. M.R.S. is supported by the NSF Graduate Research Fellowship Program under grant 1842400. S.W.J. acknowledges support from US National Science Foundation award AST-1615455. J.B. is supported by NSF grants AST-1313484 and AST1911225, as well as by NASA grant 80NSSC19kf1639. M.N. is supported by a Royal Astronomical Society Research Fellowship and by the European Research Council (ERC) under the European Unionʼs Horizon 2020 research and innovation program (grant agreement No. 948381). The work of X.W. has been provided by the National Science Foundation of China (NSFC grants 12033003 and 11633002), the Major State Basic Research Development Program (grant 2016YFA0400803), and the Scholar Program of Beijing Academy of Science and Technology (DZ: BS202002).application/pdfen-AU© 2021. The American Astronomical SocietyType Ia supernovaeSupernovaetime domain astronomy202110.3847/1538-4357/ac2c842022-11-13