ZTF SN Ia DR2: The spectral diversity of Type Ia supernovae in a volume-limited sample

Abstract

More than 3000 spectroscopically confirmed Type Ia supernovae (SNe Ia) are presented in the Zwicky Transient Facility SN Ia Data Release 2 (ZTF DR2). In this paper, we detail the spectral properties of 482 SNe Ia near maximum light, up to a redshift limit of $z$ $\le$ 0.06. We measure the velocities and pseudo-equivalent widths (pEW) of key spectral features (Si II $\lambda$5972 and Si II $\lambda$6355) and investigate the relation between the properties of the spectral features and the photometric properties from the SALT2 light-curve parameters as a function of spectroscopic sub-class. We discuss the non-negligible impact of host galaxy contamination on SN Ia spectral classifications, as well as investigate the accuracy of spectral template matching of the ZTF DR2 sample. We define a new subclass of underluminous SNe Ia (`04gs-like') that lie spectroscopically between normal SNe Ia and transitional 86G-like SNe Ia (stronger Si II $\lambda$5972 than normal SNe Ia but significantly weaker Ti II features than `86G-like' SNe). We model these `04gs-like' SN Ia spectra using the radiative-transfer spectral synthesis code tardis and show that cooler temperatures alone are unable to explain their spectra; some changes in elemental abundances are also required. However, the broad continuity in spectral properties seen from bright (`91T-like') to faint normal SN Ia, including the transitional and 91bg-like SNe Ia, suggests that variations within a single explosion model may be able to explain their behaviour.

References in corpus (33)

• The Zwicky Transient Facility: Data Processing, Products, and Archive
• The Zwicky Transient Facility: Science Objectives
• Rates and properties of type Ia supernovae as a function of mass and star-formation in their host galaxies
• The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star
• Determining the Type, Redshift, and Age of a Supernova Spectrum
• The Zwicky Transient Facility: Surveys and Scheduler
• The Zwicky Transient Facility: Observing System
• Improved Distances to Type Ia Supernovae with Two Spectroscopic Subclasses
• The Spectroscopic Diversity of Type Ia Supernovae
• Optical and Near-Infrared Observations of the Highly Reddened, Rapidly Expanding Type Ia Supernova 2006X in M100
• Evidence for Two Distinct Populations of Type Ia Supernovae
• The GROWTH Marshal: A Dynamic Science Portal for Time-Domain Astronomy
• A Fully Automated Integral Field Spectrograph Pipeline for the SEDMachine: pysedm
• Exploring the spectral diversity of low-redshift Type Ia supernovae using the Palomar Transient Factory
• Comparative Direct Analysis of Type Ia Supernova Spectra. V. Insights from A Larger Sample and Quantitative Subclassification
• Optical and IR observations of SN 2002dj: some possible common properties of fast expanding SNe Ia
• Supernova 2002ic: the collapse of a stripped-envelope, massive star in a dense medium ?
• A data science platform to enable time-domain astronomy
• Progenitors of type Ia supernovae
• New Modules for the SEDMachine to Remove Contaminations from Cosmic Rays and Non-target Light: BYECR and CONTSEP
• Abundance stratification in Type Ia supernovae - V. SN 1986G bridging the gap between normal and subluminous SNe Ia
• The lowest of the low: discovery of SN 2019gsc and the nature of faint Iax supernovae
• Carnegie Supernova Project: Classification of Type Ia Supernovae
• The Absolute Magnitudes of 1991T-like Supernovae
• The Foundation Supernova Survey: Photospheric Velocity Correlations in Type Ia Supernovae
• Using 1991T/1999aa-like Type Ia Supernovae as Standardizable Candles
• Probabilistic Reconstruction of Type Ia Supernova SN 2002bo
• ZTF SN Ia DR2: Study of Type Ia Supernova lightcurve fits
• Type Ia Supernova Progenitor Properties and Their Host Galaxies
• Repeated pattern of $\gamma$-ray flares in the blazar PKS 1502+106 coincident with the IC190730A neutrino event
• A study of Si II and S II features in spectra of Type Ia supernova
• Light curve properties of SN 2017fgc and HV SNe Ia
• Early-time spectroscopic modelling of the transitional Type Ia Supernova 2021rhu with TARDIS

Cited by in corpus (7)

• Searching for late-time interaction signatures in Type Ia supernovae from the Zwicky Transient Facility
• ZTF SN Ia DR2: High-velocity components in the Si II $\lambda$6355
• ZTF SN Ia DR2: Properties of the low-mass host galaxies of Type Ia supernovae in a volume-limited sample
• ZTF SN Ia DR2: The secondary maximum in Type Ia supernovae
• ZTF SN Ia DR2 follow-up: Exploring the origin of the Type Ia supernova host galaxy step through Si II velocities
• A real-time search for Type Ia Supernovae with late-time CSM interaction in ZTF
• Calcium versus silicon ejecta velocities and decline rates in supernovae Ia: The role of high-velocity features