Subclasses of Type Ia Supernovae as the origin of [\alpha/Fe] ratios in dwarf spheroidal galaxies

TL;DR

This paper explores diverse subclasses of Type Ia Supernovae, including SNe Iax and sub-Chandrasekhar mass explosions, and their roles in shaping the chemical evolution and [α/Fe] ratios in dwarf spheroidal galaxies.

Contribution

It introduces new progenitor channels for SNe Ia, emphasizing their impact on chemical evolution in metal-poor systems and providing a model consistent with observed abundance patterns.

Findings

SNe Iax produce high [Mn/Fe] ratios.

Sub-Ch-mass SNe Ia yield low [Mn/Fe].

A mixed model explains observed [α/Fe] ratios in dwarf galaxies.

Abstract

Recent extensive observations of Type Ia Supernovae (SNe Ia) have revealed the existence of a diversity of SNe Ia, including SNe Iax. We introduce two possible channels in the single degenerate scenario: 1) double detonations in sub-Chandrasekhar (Ch) mass CO white dwarfs (WDs), where a thin He envelope is developed with relatively low accretion rates after He novae even at low metallicities, and 2) carbon deflagrations in Ch-mass possibly hybrid C+O+Ne WDs, where WD winds occur at [Fe/H] ~ -2.5 at high accretion rates. These subclasses of SNe Ia are rarer than `normal' SNe Ia and do not affect the chemical evolution in the solar neighborhood, but can be very important in metal-poor systems with stochastic star formation. In dwarf spheroidal galaxies in the Local Group, the decrease of [\alpha/Fe] ratios at [Fe/H] ~ -2 to -1.5 can be produced depending on the star formation history. SNe Iax give high [Mn/Fe], while sub-Ch-mass SNe Ia give low [Mn/Fe], and thus a model including a mix of the two is favoured by the available observations.