Nebular-Phase Spectra of Nearby Type Ia Supernovae

Abstract

We present late-time spectra of eight Type Ia supernovae (SNe Ia) obtained at $>200$ days after peak brightness using the Gemini South and Keck telescopes. All of the SNe Ia in our sample were nearby, well separated from their host galaxy's light, and have early-time photometry and spectroscopy from the Las Cumbres Observatory (LCO). Parameters are derived from the light curves and spectra such as peak brightness, decline rate, photospheric velocity, and the widths and velocities of the forbidden nebular emission lines. We discuss the physical interpretations of these parameters for the individual SNe Ia and the sample in general, including comparisons to well-observed SNe Ia from the literature. There are possible correlations between early-time and late-time spectral features that may indicate an asymmetric explosion, so we discuss our sample of SNe within the context of models for an offset ignition and/or white dwarf collisions. A subset of our late-time spectra are uncontaminated by host emission, and we statistically evaluate our nondetections of H$\alpha$ emission to limit the amount of hydrogen in these systems. Finally, we consider the late-time evolution of the iron emission lines, finding that not all of our SNe follow the established trend of a redward migration at $>200$ days after maximum brightness.

20 pages, 8 figures, 9 tables; accepted to MNRAS

References in corpus (12)

• A Common Explosion Mechanism for Type Ia Supernovae
• The Spectroscopic Diversity of Type Ia Supernovae
• SOUSA: the Swift Optical/Ultraviolet Supernova Archive
• Kinematics of the Local Universe XIII. 21-cm line measurements of 452 galaxies with the Nançay radiotelescope, JHK Tully-Fisher relation and preliminary maps of the peculiar velocity field
• Constraining the Type Ia Supernova Progenitor: The Search for Hydrogen in Nebular Spectra
• Type Ia Supernovae as Stellar Endpoints and Cosmological Tools
• The Northern HIPASS catalogue - Data presentation, completeness and reliability measures
• SFI++ II: A New I-band Tully-Fisher Catalog, Derivation of Peculiar Velocities and Dataset Properties
• Nebular spectra and abundance tomography of the type Ia supernova SN 2011fe: a normal SN Ia with a stable Fe core
• Early observations of the nearby type Ia supernova SN 2015F
• Twins for life? A comparative analysis of the Type Ia supernovae 2011fe and 2011by
• The ANU WiFeS SuperNovA Program (AWSNAP)

Cited by in corpus (33)

• Type Ia Supernova Explosions in Binary Systems: A Review
• Multi-Dimensional Radiative Transfer Calculations of Double Detonations of Sub-Chandrasekhar-Mass White Dwarfs
• Sub-Chandrasekhar progenitors favoured for type Ia supernovae: Evidence from late-time spectroscopy
• Carnegie Supernova Project: The First Homogeneous Sample of "Super-Chandrasekhar Mass"/2003fg-like Type Ia Supernova
• Nebular Spectroscopy of Kepler's Brightest Supernova
• SN 2013aa and SN 2017cbv: Two Sibling Type Ia Supernovae in the spiral galaxy NGC 5643
• A Carbon/Oxygen-dominated Atmosphere Days After Explosion for the "Super-Chandrasekhar" Type Ia SN 2020esm
• JWST Low-Resolution MIRI Spectral Observations of SN~2021aefx: High-density Burning in a Type Ia Supernova
• Measuring an off-Center Detonation through Infrared Line Profiles: The peculiar Type Ia Supernova SN~2020qxp/ASASSN-20jq
• Spectral signatures of H-rich material stripped from a non-degenerate companion by a Type Ia supernova
• Spectroscopic Studies of Type Ia Supernovae Using LSTM Neural Networks
• Nebular H$\alpha$ Limits for Fast Declining Type Ia Supernovae
• A Rapid Ionization Change in the Nebular-Phase Spectra of the Type Ia SN 2011fe
• Optical and Near-Infrared Observations of the Nearby Type Ia Supernova 2017cbv
• The Whisper of a Whimper of a Bang: 2400 Days of the Type Ia SN 2011fe Reveals the Decay of ${}^{55}$Fe
• The Early Light Curve of SN 2023bee: Constraining Type Ia Supernova Progenitors the Apian Way
• Nebular-Phase Spectra of Type Ia Supernovae from the Las Cumbres Observatory Global Supernova Project
• Searching for a Hypervelocity White Dwarf Companion: A Proper Motion Survey of SN 1006
• Photometric and spectroscopic evolution of the peculiar Type IIn SN 2012ab
• Type Ia Supernova Progenitor Properties and Their Host Galaxies
• Near-infrared and Optical Nebular-phase Spectra of Type Ia Supernovae SN 2013aa and SN 2017cbv in NGC 5643
• SN 2019ein: A Type Ia Supernova Likely Originated from a Sub-Chandrasekhar-Mass Explosion
• SN 2022joj: A Peculiar Type Ia Supernova Possibly Driven by an Asymmetric Helium-shell Double Detonation
• Bright Type IIP Supernovae in Low-Metallicity Galaxies
• Galactic Positrons from Thermonuclear Supernovae
• The Search for Stable Nickel: Investigating the Origins of Type Ia Supernovae with Late-time NIR Spectroscopy from the Carnegie Supernova Project-II
• Detection of [C I] Emission in Nebular Spectra of a Peculiar Type Ia Supernova 2022pul
• Characterization of Supernovae Based on the Spectral-Temporal Energy Distribution: Possible two SN Ib Subtypes
• Including a Luminous Central Remnant in Radiative Transfer Simulations for Type Iax Supernovae
• Producing type Ia supernovae from hybrid CONe white dwarfs with main-sequence binary companions at low metallicity of Z = 0.0001
• $\texttt{HostSub_GP}$: Precise Galaxy Background Subtraction in Transient Long-slit Spectroscopy with Gaussian Processes
• Circumstellar Medium Constraints on the Environment of Two Nearby Type Ia Supernovae: SN 2017cbv and SN 2020nlb
• Normal or transitional? The evolution and properties of two type Ia supernovae in the Virgo cluster