Merging of Components in Close Binaries: Type Ia Supernovae, Massive White Dwarfs, and Ap stars

TL;DR

This paper uses a population synthesis code to study merging binary systems, revealing implications for Type Ia supernovae as standard candles, white dwarf origins, and the formation of magnetic stars.

Contribution

It provides new insights into the rates, energy variations, and evolutionary implications of merging binary systems, including supernovae and star formation processes.

Findings

Type Ia supernovae energy decreases by about 10% after 1 billion years.

Maximum and minimum energies of Type Ia supernovae differ by at least 1.5 times.

Magnetic white dwarfs and some Ap stars likely originate from mergers of lower-mass stars.

Abstract

The "Scenario Machine" (a computer code designed for studies of the evolution of close binaries) was used to carry out a population synthesis for a wide range of merging astrophysical objects: main-sequence stars with main-sequence stars; white dwarfs with white dwarfs, neutron stars, and black holes; neutron stars with neutron stars and black holes; and black holes with black holes.We calculate the rates of such events, and plot the mass distributions for merging white dwarfs and main-sequence stars. It is shown that Type Ia supernovae can be used as standard candles only after approximately one billion years of evolution of galaxies. In the course of this evolution, the average energy of Type Ia supernovae should decrease by roughly 10%; the maximum and minimum energies of Type Ia supernovae may differ by no less than by a factor of 1.5. This circumstance should be taken into account in estimations of parameters of acceleration of the Universe. According to theoretical estimates, the most massive - as a rule, magnetic - white dwarfs probably originate from mergers of white dwarfs of lower mass. At least some magnetic Ap and Bp stars may form in mergers of low-mass main sequence stars (<1.5 mass of the Sun) with convective envelopes.