Mass transfer stability for AM CVn binaries with white dwarf donors

Fuente: arXiv
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Main Authors: McNeill, Lucy O., Hirai, Ryosuke
Format: Preprint
Published: 2025
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author McNeill, Lucy O.
Hirai, Ryosuke
author_facet McNeill, Lucy O.
Hirai, Ryosuke
contents Double white dwarf binaries (DWDBs) with Helium components are progenitors to AM CVn binary systems. Their Galactic production rate may be given by the number of stably mass transferring DWDBs in the Milky Way. The theoretical criteria for stable mass transfer in DWDBs is calculated assuming that component white dwarfs are completely cold and degenerate. Respective fractions of surviving AM CVn and DWDB which merge are then calculated by applying this criteria to population synthesis estimates for Galactic DWDB. However, emerging observations of the local DWDB population suggest that Helium white dwarf (He WD) components are typically hot, and only partially degenerate when they begin mass transferring. Using recent numerical simulations of He WD donors in DWDBs, we qualitatively describe a temperature dependent stable mass transfer criteria for Galactic DWDBs. Mass transfer is even more stable than previously thought, or equivalently, DWDB mergers are even rarer. Realistic finite temperature treatments will deepen the dearth in observed AM CVn binaries compared to DWDB merger products.
format Preprint
id arxiv_https___arxiv_org_abs_2512_01377
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Mass transfer stability for AM CVn binaries with white dwarf donors
McNeill, Lucy O.
Hirai, Ryosuke
Solar and Stellar Astrophysics
High Energy Astrophysical Phenomena
Double white dwarf binaries (DWDBs) with Helium components are progenitors to AM CVn binary systems. Their Galactic production rate may be given by the number of stably mass transferring DWDBs in the Milky Way. The theoretical criteria for stable mass transfer in DWDBs is calculated assuming that component white dwarfs are completely cold and degenerate. Respective fractions of surviving AM CVn and DWDB which merge are then calculated by applying this criteria to population synthesis estimates for Galactic DWDB. However, emerging observations of the local DWDB population suggest that Helium white dwarf (He WD) components are typically hot, and only partially degenerate when they begin mass transferring. Using recent numerical simulations of He WD donors in DWDBs, we qualitatively describe a temperature dependent stable mass transfer criteria for Galactic DWDBs. Mass transfer is even more stable than previously thought, or equivalently, DWDB mergers are even rarer. Realistic finite temperature treatments will deepen the dearth in observed AM CVn binaries compared to DWDB merger products.
title Mass transfer stability for AM CVn binaries with white dwarf donors
topic Solar and Stellar Astrophysics
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2512.01377