SN 2022joj: A Peculiar Type Ia Supernova Possibly Driven by an Asymmetric Helium-shell Double Detonation

Abstract

We present observations of SN 2022joj, a peculiar Type Ia supernova (SN Ia) discovered by the Zwicky Transient Facility (ZTF). SN 2022joj exhibits an unusually red $g_{\mathrm{ZTF}}-r_{\mathrm{ZTF}}$ color at early times and a rapid blueward evolution afterward. Around maximum brightness, SN 2022joj shows a high luminosity ($M_{g_{\mathrm{ZTF}},\max }\simeq -19.7$ mag), a blue broadband color ($g_{\mathrm{ZTF}}-r_{\mathrm{ZTF}}\simeq -0.2$ mag), and shallow Si II absorption lines, consistent with those of overluminous, SN 1991T-like events. The maximum-light spectrum also shows prominent absorption around 4200 Å, which resembles the Ti II features in subluminous, SN 1991bg-like events. Despite the blue optical-band colors, SN 2022joj exhibits extremely red ultraviolet minus optical colors at maximum luminosity ($u-v\simeq 0.6$ mag and $uvw1-v\simeq 2.5$ mag), suggesting a suppression of flux at $\sim$2500--4000 Å. Strong C II lines are also detected at peak. We show that these unusual spectroscopic properties are broadly consistent with the helium-shell double detonation of a sub-Chandrasekhar mass ($M\simeq 1{\mathrm{M}}_{\odot }$) carbon/oxygen (C/O) white dwarf (WD) from a relatively massive helium shell ($M_s\simeq 0.04$--$0.1{\mathrm{M}}_{\odot }$), if observed along a line of sight roughly opposite to where the shell initially detonates. None of the existing models could quantitatively explain all the peculiarities observed in SN 2022joj. The low flux ratio of [Ni II] $\lambda$7378 to [Fe II] $\lambda$7155 emission in the late-time nebular spectra indicates a low yield of stable Ni isotopes, favoring a sub-Chandrasekhar mass progenitor. The significant blueshift measured in the [Fe II] $\lambda$7155 line is also consistent with an asymmetric chemical distribution in the ejecta, as is predicted in double-detonation models.

24 pages, 11 figures, 6 tables. Updated to accepted version (ApJ)

References in corpus (48)

• Array Programming with NumPy
• The Zwicky Transient Facility: System Overview, Performance, and First Results
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• The Zwicky Transient Facility: Data Processing, Products, and Archive
• The Zwicky Transient Facility: Science Objectives
• The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star
• Determining the Type, Redshift, and Age of a Supernova Spectrum
• Double-detonation sub-Chandrasekhar supernovae: can minimum helium shell masses detonate the core?
• Spectropolarimetry of Supernovae
• The Zwicky Transient Facility: Surveys and Scheduler
• Time Dependent Monte Carlo Radiative Transfer Calculations For 3-Dimensional Supernova Spectra, Lightcurves, and Polarization
• The Zwicky Transient Facility: Observing System
• Double-detonation sub-Chandrasekhar supernovae: synthetic observables for minimum helium shell mass models
• Cosmological parameters from the comparison of peculiar velocities with predictions from the 2M++ density field
• The Automated Palomar 60-Inch Telescope
• Type Ia Supernova Explosions in Binary Systems: A Review
• A Fully Automated Integral Field Spectrograph Pipeline for the SEDMachine: pysedm
• Optical Spectroscopy of Type Ia Supernovae
• The Zwicky Transient Facility Alert Distribution System
• Machine Learning for the Zwicky Transient Facility
• A hybrid type Ia supernova with an early flash triggered by helium-shell detonation
• Binospec: A Wide-field Imaging Spectrograph for the MMT
• ZTF Early Observations of Type Ia Supernovae I: Properties of the 2018 Sample
• Exploring the spectral diversity of low-redshift Type Ia supernovae using the Palomar Transient Factory
• Nebular spectra and abundance tomography of the type Ia supernova SN 2011fe: a normal SN Ia with a stable Fe core
• Double Detonations with Thin, Modestly Enriched Helium Layers Can Make Normal Type Ia Supernovae
• A data science platform to enable time-domain astronomy
• Early light curves for Type Ia supernova explosion models
• Supersolar Ni/Fe production in the Type IIP SN 2012ec
• Asymmetric Explosion of Type Ia Supernovae as Seen from Near Infrared Observations
• 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
• Double-Detonation Models for Type Ia Supernovae: Trigger of Detonation in Companion White Dwarfs and Signatures of Companions' Stripped-off Materials
• Sub-Chandrasekhar progenitors favoured for type Ia supernovae: Evidence from late-time spectroscopy
• Ultraviolet Observations of Super-Chandrasekhar Mass Type Ia Supernova Candidates with Swift UVOT
• Predicting polarization signatures for double-detonation and delayed-detonation models of Type Ia supernovae
• OGLE-2013-SN-079: a lonely supernova consistent with a helium shell detonation
• Evidence for sub-Chandrasekhar Type Ia supernovae from the last major merger
• Stable nickel production in Type Ia supernovae: A smoking gun for the progenitor mass?
• Infant-phase reddening by surface Fe-peak elements in a normal Type Ia Supernova
• The fastest stars in the Galaxy
• Exploring the diversity of double detonation explosions for type Ia supernovae: Effects of the post-explosion helium shell composition
• Can Helium-detonation Model Explain the Observed Diversity of Type Ia Supernovae?
• Observational constraints on the origin of the elements. V. Non-LTE abundance ratios of [Ni/Fe] in Galactic stars and enrichment by sub-Chandrasekhar mass SNe
• The origin and evolution of the normal Type Ia SN 2018aoz with infant-phase reddening and excess emission
• Modelling the ionisation state of Type Ia supernovae in the nebular-phase
• SN 2016dsg: A Thermonuclear Explosion Involving A Thick Helium Shell
• Peculiar Spectral Evolution of the Type I Supernova 2019eix: A Possible Double Detonation from a Helium Shell on a Sub-Chandrasekhar-mass White Dwarf

Cited by in corpus (3)

• Exploring the range of impacts of helium in the spectra of double detonation models for Type Ia supernovae
• $\texttt{HostSub_GP}$: Precise Galaxy Background Subtraction in Transient Long-slit Spectroscopy with Gaussian Processes
• Deciphering the explosion mechanism of Type Ia SNe using their remnants II: a deep dive into double detonations with SNR 0509-67.5