The Evolution of Cataclysmic Variables

TL;DR

This paper reviews the current understanding of cataclysmic variable evolution, focusing on theoretical models, observational tests, and empirical reconstruction of their evolutionary paths, highlighting potential discrepancies with standard models.

Contribution

It synthesizes recent theoretical, observational, and empirical studies on CV evolution, emphasizing the need to revise angular momentum loss assumptions.

Findings

Observational tests challenge the standard disrupted magnetic braking model.

Empirical reconstructions suggest enhanced angular momentum loss below the period gap.

Recent studies indicate potential revisions to CV evolutionary theories.

Abstract

I review our current understanding of the evolution of cataclysmic variables (CVs). I first provide a brief introductory "CV primer", in which I describe the physical structure of CVs, as well as their astrophysical significance. The main part of the review is divided into three parts. The first part outlines the theoretical principles of CV evolution, focusing specifically on the standard "disrupted magnetic braking" model. The second part describes how some of the most fundamental predictions this model are at last being test observationally. Finally, the third part describes recent efforts to actually reconstruct the evolution path of CVs empirically. Some of these efforts suggest that angular momentum loss below the period gap must be enhanced relative to the purely gravitational-radiation-driven losses assumed in the standard model.