On the possible observational signatures of white dwarf dynamical interactions

TL;DR

This paper analyzes the potential observational signals from white dwarf interactions, including gravitational waves, light curves, neutrino emissions, and X-ray signatures, to aid future detection efforts.

Contribution

It provides the first detailed predictions of gravitational wave, electromagnetic, and neutrino signals from various white dwarf interaction scenarios.

Findings

Eccentric binary formations are detectable by planned gravitational wave detectors.

Lateral collisions produce detectable signals with more sensitive instruments.

Interaction events result in diverse light curves and neutrino emissions, indicating powerful outbursts and low luminosity events.

Abstract

We compute the possible observational signatures of white dwarf dynamical interactions in dense stellar environments. Specifically, we compute the emission of gravitational waves, and we compare it with the sensitivity curves of planned space-borne gravitational wave detectors. We also compute the light curves for those interactions in which a detonation occurs, and one of the stars is destroyed, as well as the corresponding neutrino luminosities. We find that for the three possible outcomes of these interactions - which are the formation of an eccentric binary system, a lateral collision in which several mass transfer episodes occur, and a direct one in which just a single mass transfer episode takes place - only those in which an eccentric binary are formed are likely to be detected by the planned gravitational wave mission eLISA, while more sensitive detectors would be able to detect the signals emitted in lateral collisions. On the other hand, the light curves (and the thermal neutrino emission) of these interactions are considerably different, producing both very powerful outbursts and low luminosity events. Finally, we also calculate the X-ray signature produced in the aftermath of those interactions for which a merger occurs. We find that the temporal evolution follows a power law with the same exponent found in the case of the mergers of two neutron stars, although the total energy released is smaller.