# Thermal evolution of neo-neutron stars. I: envelopes, Eddington luminosity phase and implications for GW170817

## TL;DR

This paper investigates the early thermal evolution of neo-neutron stars, focusing on their luminosity, contraction, and observational signatures following supernovae, mergers, or white dwarf collapses.

## Contribution

It provides the first spherically symmetric model of neo-neutron stars, analyzing their luminosity limits, energy sources, and potential observability post-merger or collapse.

## Key findings

- Neo-neutron stars can sustain near-Eddington luminosities for a significant time.
- Positrons and contraction energy play crucial roles in the star's early evolution.
- Potential observability of neo-neutron stars in merger events and white dwarf collapses.

## Abstract

A neo-neutron star is a hot neutron star that has just become transparent to neutrinos. In a core collapse supernova or accretion induced collapse of a white dwarf the neo-neutron star phase directly follows the proto-neutron star phase, about 30 to 60 seconds after the initial collapse. It will also be present in a binary neutron star merger in the case the "born-again" hot massive compact star does not immediately collapse into a black hole. Eddington or even super-Eddington luminosities are present for some time. A neo-neutron star produced in a core collapse supernova is not directly observable but the one produced by a binary merger, likely associated with an off-axis short gamma-ray burst, may be observable for some time as well as when produced in the accretion induced collapse of a white dwarf. We present a first step in the study of this neo-neutron star phase in a spherically symmetric configuration, thus neglecting fast rotation, and also neglecting the effect of strong magnetic fields. We put particular emphasis on determining how long the star can sustain a near-Eddington luminosity and also show the importance of positrons and contraction energy during neo-neutron star phase. We finally discuss the observational prospects for neutron star mergers triggered by LIGO and for accretion-induced collapse transients.