X-ray observations of classical novae. Theoretical implications

TL;DR

This paper reviews X-ray observations of classical novae, highlighting their significance in understanding explosion mechanisms, white dwarf behavior, and implications for supernova scenarios, with a focus on the duration of post-outburst H-burning.

Contribution

It provides a comprehensive review of X-ray data on classical novae and discusses their theoretical implications for nova evolution and supernova progenitors.

Findings

Soft X-rays indicate ongoing hydrogen burning on white dwarfs.

Hard X-rays provide insights into ejecta and accretion flows.

Recurrent novae may have short recurrence periods relevant for supernova models.

Abstract

Detection of X-rays from classical novae, both in outburst and post-outburst, provides unique and crucial information about the explosion mechanism. Soft X-rays reveal the hot white dwarf photosphere, whenever hydrogen (H) nuclear burning is still on and expanding envelope is transparent enough, whereas harder X-rays give information about the ejecta and/or the accretion flow in the reborn cataclysmic variable. The duration of the supersoft X-ray emission phase is related to the turn-off of the classical nova, i.e., of the H-burning on top of the white dwarf core. A review of X-ray observations is presented, with a special emphasis on the implications for the duration of post-outburst steady H-burning and its theoretical explanation. The particular case of recurrent novae (both the "standard" objects and the recently discovered ones) is also reviewed, in terms of theoretical feasibility of short recurrence periods, as well as regarding implications for scenarios of type Ia supernovae.