Exploring Type Iax supernovae observables and progenitors through one-dimensional radiation-hydrodynamics simulations of CO white dwarfs

Early-time radioactive signals from type Ia supernovae (SNeIa) can provide important constraints on the explosion mechanism and the progenitor system. We investigate whether shock ignition models of Chandresehkar-mass carbon oxygen white dwarf stars in the SD WD-He star scenario can account for observed population of the Type Iax supernovae (SN Iax) explosions. We compute 8 1D full-star radiation-hydrodynamic explosion models (using SNEC) from a WD model accreting pure helium from its helium star companion (using MESA), and compare their synthetic light curves as well as other profiles with that of well-observed real SNe Iax. In addition, we explore how the amount of nickel placed from the core of WD would shape these light curves. We find the ⁵⁶ Ni shows a directly proportional relationship to peak luminosity, as peak luminosities of some models match to corresponding SNe Iax with calculated nickel masses. We find that synthetic lightcurves of our models predict early time light curves of observed SNe Iax fairly well, while more discrepancies arise after ~40 days after explosion. Which suggests that real SNe Iax has a more efficient γ-ray deposition in later times than models. This is also shown through color light curves, where model with M _Ni =0.25M _⊙ has a decline rate of Δm ₁₅ (B)=2.57 mag. Models also predict low-energy SNe better, such as with SN 2023mnc, SN 2019gsc, and SN 2019muj. The photospheric velocity of models reaches a peak kick velocity of ~167000 kms ^-1 for an E _exp =1.63x10 ⁵² erg explosion and then quickly decelerates to stationary at ~15 days. We find that velocity profile of the models shows similar deceleration rate as real SNe Iax and the power law after its been scaled by a factor of 0.1 to match SNe Iax explosion energies.