Thermal evolution of neo-neutron stars. II. Temperature-dependent crusts
Abstract
The neo-neutron star phase is an intermediate stage in the evolution from a hot, lepton-rich compact object, which is formed in the aftermath of a core-collapse supernova or an accretion-induced collapse of a white dwarf, to a cold deleptonized neutron star (NS). Alternatively, this phase can occur after a binary NS merger if the final compact object does not collapse immediately into a black hole. Radial temperature profiles provided by numerical simulations of proto-NS evolution suggest that the composition and mechanical structure of the star's core at the beginning of the neo-NS phase are approximately identical to those of a cold NS. In contrast, the composition and mechanical structure of the outer layers (i.e., the crust) are expected to change as the star cools. The thermal evolution of neo-NSs with temperature-dependent (inner) envelopes was considered by Beznogov et al. (2020). Here, we investigated what happens if the equation of state (EoS) of the entire crust, including its composition, depends on temperature. We analyzed the thermal, mechanical, and chemical evolution of neo-NSs by further developing and employing neo-NSCool, our NS thermal evolution code. First, we show that thermally dripped neutrons slightly slow down the cooling during the early thermal relaxation stage. Then, we demonstrate that the EoSs featuring exotic light species in the deepest layers of the crust result in significantly slower cooling in the photon-cooling era compared to the EoSs that favor massive nuclei. The crust's composition also impacts the crystallization process as well as the contraction of the crust during cooling. The EoSs with light nuclei cause the innermost layers to remain liquid for a longer time than the EoSs with heavy nuclei.
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BibTeX
@misc{chatterjee2026thermal,
title = {{Thermal evolution of neo-neutron stars. II. Temperature-dependent crusts}},
author = {Sagnik Chatterjee and Mikhail V. Beznogov and Dany Page and Adriana R. Raduta},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.03732},
eprint = {2608.03732},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.03732},
}
RIS
TY - UNPB
TI - Thermal evolution of neo-neutron stars. II. Temperature-dependent crusts
AU - Sagnik Chatterjee
AU - Mikhail V. Beznogov
AU - Dany Page
AU - Adriana R. Raduta
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2608.03732
UR - https://arxiv.org/abs/2608.03732
AB - The neo-neutron star phase is an intermediate stage in the evolution from a hot, lepton-rich compact object, which is formed in the aftermath of a core-collapse supernova or an accretion-induced collapse of a white dwarf, to a cold deleptonized neutron star (NS). Alternatively, this phase can occur after a binary NS merger if the final compact object does not collapse immediately into a black hole. Radial temperature profiles provided by numerical simulations of proto-NS evolution suggest that the composition and mechanical structure of the star's core at the beginning of the neo-NS phase are approximately identical to those of a cold NS. In contrast, the composition and mechanical structure of the outer layers (i.e., the crust) are expected to change as the star cools. The thermal evolution of neo-NSs with temperature-dependent (inner) envelopes was considered by Beznogov et al. (2020). Here, we investigated what happens if the equation of state (EoS) of the entire crust, including its composition, depends on temperature. We analyzed the thermal, mechanical, and chemical evolution of neo-NSs by further developing and employing neo-NSCool, our NS thermal evolution code. First, we show that thermally dripped neutrons slightly slow down the cooling during the early thermal relaxation stage. Then, we demonstrate that the EoSs featuring exotic light species in the deepest layers of the crust result in significantly slower cooling in the photon-cooling era compared to the EoSs that favor massive nuclei. The crust's composition also impacts the crystallization process as well as the contraction of the crust during cooling. The EoSs with light nuclei cause the innermost layers to remain liquid for a longer time than the EoSs with heavy nuclei.
ER -