The evolution of relative frequencies of ONe and CO SNe Ia

TL;DR

This study investigates how the changing ratio of ONe and CO white dwarf mergers influences Type Ia supernovae frequencies and brightness, potentially affecting cosmological interpretations of universe expansion.

Contribution

It provides a population synthesis analysis of ONe and CO white dwarf merger frequencies and their impact on SNe Ia properties over cosmic time.

Findings

The ratio of ONe to CO WD mergers varies with time.

Mass scatter in progenitors affects SNe Ia brightness.

Evolution of WD merger ratios may explain supernova dimming at high redshift.

Abstract

In this population synthesis work we study a variety of possible origin channels of supernovae type Ia (SNe Ia) Among them mergers of carbon-oxygen (CO) and oxygen-neon (ONe) white dwarfs (WDs) under the influence of gravitational waves are considered as the primary channel of SNe Ia formation. We estimated frequencies of mergers of WDs with different chemical compositions and distributions of masses of merging WDs. We computed the dependence of the ratio of merger frequencies of ONe and CO WDs as primaries in corresponding binaries on time. The scatter of masses of considered sources (up to the factor $1.5-2$) of SNe Ia is important and should be carefully studied with other sophisticated methods from theoretical point of view. Our ``game of parameters'' potentially explains the increased dimming of SNe Ia in the redshift range $z\approx 0.5-1$ by the changes in the ratio of ONe and CO WDs, i.e., to describe the observed accelerated expansion of the Universe in terms of the evolution of properties of SNe Ia instead of cosmological explanations. This example shows the extreme importance of theoretical studies of problems concerning SNe Ia, because evolutionary scenario and parameter games in nature potentially lead to confusions in their empirical standardization and, therefore, they can influence on cosmological conclusions.