The origins of Calcium-rich supernovae from disruptions of CO white-dwarfs by hybrid He-CO white-dwarfs

Abstract

Calcium-rich (SN 2005E-like) explosions are very faint (typical -15.5, type I supernovae (SNe) showing strong Ca-lines, mostly observed in old stellar environments. Several models for such SNe had been explored and debated, but non were able to consistently reproduce the observed properties of Ca-rich SNe, nor their rates and host-galaxy distributions. Here we show that the disruptions of low-mass carbon-oxygen (CO) white dwarfs (WDs) by hybrid Helium-CO (HeCO) WDs during their merger could explain the origin and properties of such SNe. We make use of detailed multi-dimensional hydrodynamical-thermonuclear (FLASH) simulations models of HeCO-CO WD-WD mergers to characterize such explosions. We find that the accretion of CO material onto a HeCO-WD heats its He-shell and eventually leads to its "weak" detonation and ejection and the production of a sub-energetic $\sim 10^{49}$erg Ca-rich SN, while leaving the CO core of the HeCO-WD intact as a hot remnant white dwarf, possibly giving rise to X-ray emission as it cools down. We model the detailed light-curve and spectra of such explosions to find an excellent agreement with observations of Ia/c Ca-rich SNe. In these models most of the He is burned, producing Ia/c Ca-rich SNe but higher He-enrichment levels might potentially also explain the Ib Ca-rich SNe. We thereby provide a viable, consistent model for the origins of Ca-rich. These findings can shed new light on the role of Ca-rich in the chemical evolution of galaxies and the intra-cluster medium, and their contribution to the observed 511 kev signal in the Galaxy originating from positrons produced from ${}^{44}\text{Ti}$ decay. Finally, the origins of such SNe points to the key-role of HeCO WDs as SN progenitors, and their potential role as progenitors of other thermonuclear SNe including normal type Ia SNe.

Submitted to ApJ, comments are welcome

References in corpus (24)

• Array Programming with NumPy
• Modules for Experiments in Stellar Astrophysics (MESA)
• Faint Thermonuclear Supernovae from AM Canum Venaticorum Binaries
• A binary model for the UV-upturn of elliptical galaxies (MNRAS version)
• The Zwicky Transient Facility Census of the Local Universe I: Systematic search for Calcium rich gap transients reveal three related spectroscopic sub-classes
• Mass transfer in white dwarf-neutron star binaries
• The Viscous Evolution of White Dwarf Merger Remnants
• Illuminating Massive Black Holes With White Dwarfs: Orbital Dynamics and High Energy Transients from Tidal Interactions
• A systematic study of carbon-oxygen white dwarf mergers: mass combinations for Type Ia supernovae
• Two New Calcium-Rich Gap Transients in Group and Cluster Environments
• SN 2019ehk: A Double-Peaked Ca-rich Transient with Luminous X-ray Emission and Shock-Ionized Spectral Features
• Thermonuclear explosion of a massive hybrid HeCO white-dwarf triggered by a He-detonation on a companion
• Transients from ONe White-Dwarf - Neutron-Star/Black-Hole Mergers
• One-dimensional non-LTE time-dependent radiative transfer of an He-detonation model and the connection to faint and fast-decaying supernovae
• Spiral Disk Instability Can Drive Thermonuclear Explosions in Binary White Dwarf Mergers
• Nuclear Burning in Collapsar Accretion Disks
• The Circumstellar Environments of Double-Peaked, Calcium-strong Supernovae 2021gno and 2021inl
• The peculiar Ca-rich SN 2019ehk: Evidence for a Type IIb core-collapse supernova from a low mass stripped progenitor
• No velocity-kicks are required to explain large-distance offsets of Ca-rich supernovae and short-GRBs
• A pair of CO + He white dwarfs as the progenitor of 2005E-like supernovae?
• Late-time Observations of Calcium-Rich Transient SN 2019ehk Reveal a Pure Radioactive Decay Power Source
• Calcium-rich Transient SN 2019ehk in A Star-Forming Environment: Yet Another Candidate for An Ultra-Stripped Envelope Supernova
• Transients from the Cataclysmic Deaths of Cataclysmic Variables
• Intermediate Luminosity Type Iax SN 2019muj With Narrow Absorption Lines: Long-Lasting Radiation Associated With a Possible Bound Remnant Predicted by the Weak Deflagration Model

Cited by in corpus (9)

• Panning for gold, but finding helium: discovery of the ultra-stripped supernova SN2019wxt from gravitational-wave follow-up observations
• Exploring the dependence of chemical traits on metallicity: chemical trends for red giant stars with asteroseismic ages
• The origin of hypervelocity white dwarfs in the merger-disruption of He-CO white dwarfs
• Detection of [C I] Emission in Nebular Spectra of a Peculiar Type Ia Supernova 2022pul
• Gravitational Collapse of White Dwarfs to Neutron Stars. I. From Initial Conditions to Explosions with Neutrino-radiation Hydrodynamics Simulations
• Characterizing the host galaxies and delay times of Ca-rich gap transients vs 91bg-like SNe and normal Type Ia SNe
• Normal or transitional? The evolution and properties of two type Ia supernovae in the Virgo cluster
• Helium Accumulation and Thermonuclear Instabilities on Accreting White Dwarfs: From Recurring Helium Novae to Type Ia Supernovae
• A multiwavelength view of the nearby Calcium-Strong Transient SN 2025coe in the X-Ray, Near-Infrared, and Radio Wavebands