Ruling out nucleonic direct Urca cooling in low-mass neutron stars using nuclear data
Abstract
Connecting nuclear experiments to neutron star composition requires controlling the extrapolation of experimental information beyond the densities probed in the laboratory. We combine a broad set of nuclear structure observables and INDRA-FAZIA isospin-transport data within a Bayesian inference of the dense matter equation of state (EoS). To limit uncontrolled extrapolation to high density, we employ a flexible asymptotically causal metamodel whose neutron star posteriors are comparable to those obtained with agnostic EoS models. The nuclear structure information is propagated through its full multidimensional distribution of correlated nuclear matter parameters, while the density-dependent INDRA-FAZIA likelihood is evaluated directly along each sampled metamodel symmetry energy curve. These two sources of laboratory information give compatible constraints on the symmetry energy, and their combination preserves agreement with finite nuclear observables. When combined with ab initio chiral effective field theory calculations and astrophysical observations, all these constraints substantially improve the determination of central proton fractions in low-mass neutron stars, while leaving larger uncertainties for massive stars. Within the adopted nucleonic metamodel, the reduced probability of large proton fractions strongly disfavors electronic direct-Urca onset at or below 1.4 M⊙: its posterior probability falls from ∼20% with chiral and astrophysical constraints alone to below 1% when the laboratory information is included.
Related
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- Statistical Analysis of Neutron Star Cooling: Implications for the Nuclear Equation of State and Nucleon Pairing
- Extending multi-messenger constraints on neutron star matter through the inclusion of direct Urca cooling
- A re-examination of neutron star cooling in transient sources. No shallow heating required: The role of thermonuclear heating leakage
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BibTeX
@misc{montefusco2026ruling,
title = {{Ruling out nucleonic direct Urca cooling in low-mass neutron stars using nuclear data}},
author = {Gabriele Montefusco and Pietro Klausner and Marco Antonelli and Caterina Ciampi and Diego Gruyer and Francesca Gulminelli},
howpublished = {HAL},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.24940},
eprint = {2609.24940},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05782734v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Ruling out nucleonic direct Urca cooling in low-mass neutron stars using nuclear data
AU - Gabriele Montefusco
AU - Pietro Klausner
AU - Marco Antonelli
AU - Caterina Ciampi
AU - Diego Gruyer
AU - Francesca Gulminelli
PY - 2026
DA - 2026/09/21
PB - HAL
DO - 10.48550/arxiv.2609.24940
UR - https://hal.science/hal-05782734v1
AB - Connecting nuclear experiments to neutron star composition requires controlling the extrapolation of experimental information beyond the densities probed in the laboratory. We combine a broad set of nuclear structure observables and INDRA-FAZIA isospin-transport data within a Bayesian inference of the dense matter equation of state (EoS). To limit uncontrolled extrapolation to high density, we employ a flexible asymptotically causal metamodel whose neutron star posteriors are comparable to those obtained with agnostic EoS models. The nuclear structure information is propagated through its full multidimensional distribution of correlated nuclear matter parameters, while the density-dependent INDRA-FAZIA likelihood is evaluated directly along each sampled metamodel symmetry energy curve. These two sources of laboratory information give compatible constraints on the symmetry energy, and their combination preserves agreement with finite nuclear observables. When combined with ab initio chiral effective field theory calculations and astrophysical observations, all these constraints substantially improve the determination of central proton fractions in low-mass neutron stars, while leaving larger uncertainties for massive stars. Within the adopted nucleonic metamodel, the reduced probability of large proton fractions strongly disfavors electronic direct-Urca onset at or below 1.4 M_⊙: its posterior probability falls from ∼20% with chiral and astrophysical constraints alone to below 1% when the laboratory information is included.
ER -