Twins in the Shadow: Phase Transitions in Proto-Neutron Stars
Abstract
We study the impact of a first-order phase transition from hadronic to deconfined quark matter on the evolution of proto-neutron stars. To maximize the applicability of our results, we construct an equation of state that is highly parameterizable, where we use a relativistic mean field approach to model hadronic matter and a constant speed of sound approach to model quark matter. We approximate the cooling behavior of proto-neutron stars as a sequence of decreasing entropy at constant baryonic mass. Some parameterizations lead to so-called "twin-stars", where two neutron stars have the same (gravitational) mass but different radii. Detecting them is regarded as a smoking gun signal for phase transition. We find, however, that proto-neutron star evolution suggests that gravitational twin stars are only possible if the hybrid star does not have, in addition, a baryonic twin. This rules out most twin star pairs, especially if the phase transition occurs at large densities. In a mass-radius diagram the unpopulated hybrid branch appears to be "in the shadow" of the hadronic branch.
Related
- Multi-messenger and multi-band signal from first-order phase transitions in proto-neutron stars
- The presence and order of QCD phase transitions from gravitational-wave observations of neutron star mergers
- General-purpose equations of state for hadron-quark matter: first application to accretion-induced phase transitions in neutron stars
- Effect of quark-hadron phase transitions on the neutron star mass distribution
- An updated model of neutrino emission from proto-neutron stars
BibTeX
@misc{milthaler2026twins,
title = {{Twins in the Shadow: Phase Transitions in Proto-Neutron Stars}},
author = {Jannik Milthaler and Jan-Erik Christian and Pia Jakobus and Stephan Rosswog},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.03148},
eprint = {2610.03148},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.03148},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Twins in the Shadow: Phase Transitions in Proto-Neutron Stars
AU - Jannik Milthaler
AU - Jan-Erik Christian
AU - Pia Jakobus
AU - Stephan Rosswog
PY - 2026
DA - 2026/10/02
PB - arXiv
DO - 10.48550/arxiv.2610.03148
UR - https://arxiv.org/abs/2610.03148
AB - We study the impact of a first-order phase transition from hadronic to deconfined quark matter on the evolution of proto-neutron stars. To maximize the applicability of our results, we construct an equation of state that is highly parameterizable, where we use a relativistic mean field approach to model hadronic matter and a constant speed of sound approach to model quark matter. We approximate the cooling behavior of proto-neutron stars as a sequence of decreasing entropy at constant baryonic mass. Some parameterizations lead to so-called "twin-stars", where two neutron stars have the same (gravitational) mass but different radii. Detecting them is regarded as a smoking gun signal for phase transition. We find, however, that proto-neutron star evolution suggests that gravitational twin stars are only possible if the hybrid star does not have, in addition, a baryonic twin. This rules out most twin star pairs, especially if the phase transition occurs at large densities. In a mass-radius diagram the unpopulated hybrid branch appears to be "in the shadow" of the hadronic branch.
ER -