Populations of accreting white dwarfs

TL;DR

This study models populations of accreting white dwarfs to compare their predicted emissions and nova characteristics with observations, revealing inconsistencies in supernova delay times and differences between galaxy types.

Contribution

Introduces a hybrid binary population synthesis model for accreting white dwarfs, analyzing their evolution across different star formation histories and comparing predictions with observations.

Findings

Delay time distribution of SNe Ia is inconsistent with observations.

Predicted X-ray and UV emissions match observations of early-type galaxies.

Novae in elliptical galaxies tend to have low-mass WDs and longer recurrence periods.

Abstract

Using a hybrid binary population synthesis approach, we modelled the formation and evolution of populations of accreting WDs for differing star formation histories. We found that the delay time distribution of SNe Ia in the single degenerate scenario is inconsistent with observations. Additionally, we found that our predicted X-ray and UV emission of populations of accreting WDs are consistent with the X-ray luminosities of early-type galaxies observed by Chandra and the HeII 4686\AA/H\beta line ratio measured in stacked SDSS spectra of passively evolving galaxies. Moreover, we found that the majority of current novae in elliptical-like galaxies have low-mass WDs, long decay times, long recurrence periods and are relatively faint. In contrast, the majority of current novae in spiral-like galaxies have massive WDs, short decay times, short recurrence periods and are relatively bright. Our predicted distribution of mass-loss timescales in an M31-like galaxy is consistent with observations for Andromeda.