ZTF Early Observations of Type Ia Supernovae III: Early-Time Colors as a Test for Explosion Models and Multiple Populations

Abstract

Colors of Type Ia supernovae in the first few days after explosion provide a potential discriminant between different models. In this paper, we present $g-r$ colors of 65 Type Ia supernovae 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 (${\sigma }_{\mathrm{noise}}\sim {\sigma }_{\mathrm{int}}\sim$ 0.18 mag). Colors are nearly constant starting from 6 days after first light ($g-r\sim -0.15$ 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 $\sim -0.25$ 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 ${}^{56}$Ni mixed in the outermost regions of the ejecta and with "double-detonation" models having thin helium layers ($M_{\mathrm{He}}=0.01M_{\odot }$) 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.

arXiv comment17 pages, 9 figures, 1 table; accepted for publication in ApJ; fixed error in time of first light + selection criterion changed; sample increased from 38 to 65 events; conclusions unchanged

References in corpus (50)

• The Zwicky Transient Facility: System Overview, Performance, and First Results
• The Zwicky Transient Facility: Data Processing, Products, and Archive
• The Zwicky Transient Facility: Science Objectives
• Supernova 2011fe from an Exploding Carbon-Oxygen White Dwarf Star
• Explosion Models for Type Ia Supernovae: A Comparison with Observed Light Curves, distances, H_o and q_o
• How many cosmological parameters?
• Double-detonation sub-Chandrasekhar supernovae: can minimum helium shell masses detonate the core?
• Seeing the Collision of a Supernova with its Companion Star
• K-corrections and spectral templates of Type Ia supernovae
• Comparative Direct Analysis of Type Ia Supernova Spectra. II. Maximum Light
• The Risetime of Nearby Type Ia Supernovae
• The Carnegie Supernova Project: Intrinsic Colors of Type Ia Supernovae
• The Progenitors of Type Ia Supernovae
• On the Progenitors of Type Ia Supernovae
• The Carnegie Supernova Project: Absolute Calibration and the Hubble Constant
• Observational Predictions for Sub-Chandrasekhar Mass Explosions: Further Evidence for Multiple Progenitor Systems for Type Ia Supernovae
• First-Year Sloan Digital Sky Survey-II (SDSS-II) Supernova Results: Constraints on Non-Standard Cosmological Models
• The GROWTH Marshal: A Dynamic Science Portal for Time-Domain Astronomy
• Very Early Ultraviolet and Optical Observations of the Type Ia Supernova 2009ig
• Early Blue Excess from the Type Ia Supernova 2017cbv and Implications for Its Progenitor
• A hybrid type Ia supernova with an early flash triggered by helium-shell detonation
• Exploring the Potential Diversity of Early Type Ia Supernova Light Curves
• Constraints on the explosion mechanism and progenitors of type Ia supernovae
• ZTF Early Observations of Type Ia Supernovae I: Properties of the 2018 Sample
• K2 Observations of SN 2018oh Reveal a Two-Component Rising Light Curve for a Type Ia Supernova
• Early light curves for Type Ia supernova explosion models
• Strong near-infrared carbon in the Type Ia supernova iPTF13ebh
• Seeing Double: ASASSN-18bt Exhibits a Two-Component Rise in the Early-Time K2 Light Curve
• Multi-Dimensional Double Detonation of Sub-Chandrasekhar Mass White Dwarfs
• Photometric and Spectroscopic Properties of Type Ia Supernova 2018oh with Early Excess Emission from the $Kepler$ 2 Observations
• The Very Young Type Ia Supernova 2012cg: Discovery and Early-Time Follow-Up Observations
• The Young and Bright Type Ia Supernova ASASSN-14lp: Discovery, Early-Time Observations, First-Light Time, Distance to NGC 4666, and Progenitor Constraints
• Linear spectropolarimetry of 35 Type Ia Supernovae with VLT/FORS: An analysis of the Si II line polarization
• ZTF Early Observations of Type Ia Supernovae II: First Light, the Initial Rise, and Time to Reach Maximum Brightness
• Nebular-Phase Spectra of Nearby Type Ia Supernovae
• ZTF 18aaqeasu (SN 2018byg): A Massive Helium-shell Double Detonation on a Sub-Chandrasekhar Mass White Dwarf
• Surface Radioactivity or Interactions? Multiple Origins of Early-excess Type Ia Supernovae and Associated Subclasses
• Type Ia Supernovae in the First Few Days: Signatures of Helium Detonation versus Interaction
• Early Observations of the Type Ia Supernova iPTF 16abc: A Case of Interaction with Nearby, Unbound Material and/or Strong Ejecta Mixing
• ASASSN-18tb: A Most Unusual Type Ia Supernova Observed by TESS and SALT
• Red vs Blue: Early observations of thermonuclear supernovae reveal two distinct populations?
• Determining the ${}^{56}$Ni distribution of type Ia supernovae from observations within days of explosion
• Nebular Models of Sub-Chandrasekhar Mass Type Ia Supernovae: Clues to the Origin of Ca-rich Transients
• Twins for life? A comparative analysis of the Type Ia supernovae 2011fe and 2011by
• Modelling the early time behaviour of type Ia supernovae: effects of the ${}^{56}$Ni distribution
• Ca hnk: Calcium-rich Transient SN 2016hnk from the Helium Shell Detonation of a Sub-Chandrasekhar White Dwarf
• R-band light-curve properties of Type Ia supernovae from the (intermediate) Palomar Transient Factory
• Absolute Distances to Nearby Type Ia Supernovae via Light Curve Fitting Methods
• SN 2017cfd: A Normal Type Ia Supernova Discovered Very Young
• Understanding Type Ia supernovae through their U-band spectra

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