Empirical consequential angular momentum loss can solve long standing problems of CV evolution

TL;DR

This paper proposes that empirical consequential angular momentum loss (CAML) driven by a common envelope-like process can resolve longstanding discrepancies between observations and theoretical models of cataclysmic variable evolution, including period distribution and white dwarf masses.

Contribution

It introduces an empirical CAML model that depends on white dwarf mass, explaining observed CV properties and suggesting a physical mechanism involving nova-induced common envelope evolution.

Findings

CAML increases as white dwarf mass decreases.

The model aligns binary population predictions with observations.

Proposes a nova-driven common envelope process as the physical basis.

Abstract

The observed orbital period distribution of cataclysmic variables (CVs), the space density derived from observations, and the observed orbital period minimum are known to disagree with theoretical predictions since decades. More recently, the white dwarf (WD) masses in CVs have been found to significantly exceed those of single WDs, which is in contrast to theoretical expectations as well. We here claim that all these problems are related and can be solved if CVs with low-mass white dwarfs are driven into dynamically unstable mass transfer due to consequential angular momentum loss (CAML). Indeed, assuming CAML increases as a function of decreasing white dwarf mass can bring into agreement the predictions of binary population models and the observed properties of the CV population. We speculate that a common envelope like evolution of CVs with low-mass WDs following a nova eruption might be the physical process behind our empirical prescription of CAML.