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NICER constraints on low density matching and high density continuation in neutron star equations of state
Abstract
We investigate whether current astrophysical data constrain not only the high-density continuation of the neutron star equation of state, but also the low density matching procedure itself. To this end, we compare two low density branches propagated through a common high density extension and confront them with direct NICER mass-radius posteriors, a lower bound on the maximum mass and an effective constraint on Λ1.4. We find that the observable predictions of the two branches remain strongly overlapping, while the NICER-informed posterior still induces a nontrivial constraint on the matching parameters. Current data therefore constrain primarily the shared continuation above n1, but also indirectly restrict the low density matching sector.
Versions
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BibTeX
@misc{nola2026nicer,
title = {{NICER constraints on low density matching and high density continuation in neutron star equations of state}},
author = {Federico Nola},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.07731},
eprint = {2606.07731},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.07731},
}
RIS
TY - UNPB
TI - NICER constraints on low density matching and high density continuation in neutron star equations of state
AU - Federico Nola
PY - 2026
DA - 2026/09/28
PB - arXiv
DO - 10.48550/arxiv.2606.07731
UR - https://arxiv.org/abs/2606.07731
AB - We investigate whether current astrophysical data constrain not only the high-density continuation of the neutron star equation of state, but also the low density matching procedure itself. To this end, we compare two low density branches propagated through a common high density extension and confront them with direct NICER mass-radius posteriors, a lower bound on the maximum mass and an effective constraint on Λ_1.4. We find that the observable predictions of the two branches remain strongly overlapping, while the NICER-informed posterior still induces a nontrivial constraint on the matching parameters. Current data therefore constrain primarily the shared continuation above n_1, but also indirectly restrict the low density matching sector.
ER -