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ZTF Early Observations of Type Ia Supernovae. III. Early-time Colors As a Test for Explosion Models and Multiple Populations

Bulla, Mattia and Miller, Adam A. and Yao, Yuhan and Dessart, Luc and Dhawan, Suhail and Papadogiannakis, Semeli and Biswas, Rahul and Goobar, Ariel and Kulkarni, S. R. and Nordin, Jakob and Nugent, Peter and Polin, Abigail and Sollerman, Jesper and Bellm, Eric C. and Coughlin, Michael W. and Dekany, Richard and Golkhou, V. Zach and Graham, Matthew J. and Kasliwal, Mansi M. and Kupfer, Thomas and Laher, Russ R. and Masci, Frank J. and Porter, Michael and Rusholme, Ben and Shupe, David L. (2020) ZTF Early Observations of Type Ia Supernovae. III. Early-time Colors As a Test for Explosion Models and Multiple Populations. Astrophysical Journal, 902 (1). Art. No. 48. ISSN 1538-4357. doi:10.3847/1538-4357/abb13c.

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Colors of Type Ia supernovae (SNe Ia) in the first few days after explosion provide a potential discriminant between different models. In this paper, we present g − r colors of 65 SNe Ia discovered within 5 days from first light by the Zwicky Transient Facility in 2018, a sample that is about three times larger than that in the literature. We find that g − r colors are intrinsically rather homogeneous at early phases, with about half of the dispersion attributable to photometric uncertainties (σ_(noise)∼σ_(int) ~ 0.18 mag). Colors are nearly constant starting from 6 days after first light (g − r ~ −0.15 mag), while the time evolution at earlier epochs is characterized by a continuous range of slopes, from events rapidly transitioning from redder to bluer colors (slope of ~−0.25 mag day⁻¹) to events with a flatter evolution. The continuum in the slope distribution is in good agreement both with models requiring some amount of ⁵⁶Ni mixed in the outermost regions of the ejecta and with "double-detonation" models having thin helium layers (M_(He) = 0.01 M_⊙) and varying carbon–oxygen core masses. At the same time, six events show evidence for a distinctive "red bump" signature predicted by double-detonation models with larger helium masses. We finally identify a significant correlation between the early-time g − r slopes and supernova brightness, with brighter events associated to flatter color evolution (p-value = 0.006). The distribution of slopes, however, is consistent with being drawn from a single population, with no evidence for two components as claimed in the literature based on B − V colors.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bulla, Mattia0000-0002-8255-5127
Miller, Adam A.0000-0001-9515-478X
Yao, Yuhan0000-0001-6747-8509
Dessart, Luc0000-0003-0599-8407
Dhawan, Suhail0000-0002-2376-6979
Papadogiannakis, Semeli0000-0003-0783-3323
Biswas, Rahul0000-0002-5741-7195
Goobar, Ariel0000-0002-4163-4996
Kulkarni, S. R.0000-0001-5390-8563
Nordin, Jakob0000-0001-8342-6274
Nugent, Peter0000-0002-3389-0586
Polin, Abigail0000-0002-1633-6495
Sollerman, Jesper0000-0003-1546-6615
Bellm, Eric C.0000-0001-8018-5348
Coughlin, Michael W.0000-0002-8262-2924
Dekany, Richard0000-0002-5884-7867
Golkhou, V. Zach0000-0001-8205-2506
Graham, Matthew J.0000-0002-3168-0139
Kasliwal, Mansi M.0000-0002-5619-4938
Kupfer, Thomas0000-0002-6540-1484
Laher, Russ R.0000-0003-2451-5482
Masci, Frank J.0000-0002-8532-9395
Porter, Michael0000-0003-3168-5586
Rusholme, Ben0000-0001-7648-4142
Shupe, David L.0000-0003-4401-0430
Additional Information:© 2020 The American Astronomical Society. Received 2020 January 8; revised 2020 April 14; accepted 2020 April 16; published 2020 October 9. The authors are thankful to Tony Piro for sharing his models, and to Chris Ashall, Joel Johansson, Mark Magee, Keiichi Maeda, and Stuart Sim for useful discussions. M.B. acknowledges support from the G.R.E.A.T research environment funded by the Swedish National Science Foundation. A.A.M. is funded by the Large Synoptic Survey Telescope Corporation, the Brinson Foundation, and the Moore Foundation in support of the LSSTC Data Science Fellowship Program; he also receives support as a CIERA Fellow by the CIERA Postdoctoral Fellowship Program (Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University). This research was supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at Northwestern University which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. This work was supported in part by the GROWTH project funded by the National Science Foundation under grant No. 1545949. SRK thanks the Heising-Simons Foundation for supporting his ZTF research. This work is based on observations obtained with the Samuel Oschin Telescope 48 inch and the 60 inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron, and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. This work was supported by the GROWTH project (Kasliwal et al. 2019) funded by the National Science Foundation under grant No. 1545949. Operations are conducted by COO, IPAC, and UW. This work made use of the Heidelberg Supernova Model Archive (HESMA),
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility
Funding AgencyGrant Number
Swedish National Science FoundationUNSPECIFIED
Large Synoptic Survey Telescope CorporationUNSPECIFIED
Brinson FoundationUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)UNSPECIFIED
Northwestern UniversityUNSPECIFIED
Heising-Simons FoundationUNSPECIFIED
ZTF partner institutionsUNSPECIFIED
Subject Keywords:Surveys ; Supernovae ; Type Ia supernovae
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Surveys (1671); Supernovae (1668); Type Ia supernovae (1728)
Record Number:CaltechAUTHORS:20200414-083356186
Persistent URL:
Official Citation:Mattia Bulla et al 2020 ApJ 902 48
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102523
Deposited By: Tony Diaz
Deposited On:14 Apr 2020 15:59
Last Modified:16 Nov 2021 18:12

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