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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2507.10025 |
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| _version_ | 1866916992297992192 |
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| author | Tang, Shao-Peng Huang, Yong-Jia Fan, Yi-Zhong |
| author_facet | Tang, Shao-Peng Huang, Yong-Jia Fan, Yi-Zhong |
| contents | The possible occurrence of a first-order hadron-quark phase transition (FOPT) in neutron-star interiors remains an open question. Whether such a transition can be directly tested with improved observations is a key challenge. Here, we incorporate the latest constraints, especially a new NICER radius measurement for PSR J0614--3329, into a nonparametric Gaussian Process (GP) EOS framework that explicitly includes a first-order transition. We find a Bayes factor of $B\approx2.3$ when comparing models with and without an explicit phase transition, marginally favoring its presence. At $68\%$ credibility, the transition onset density $n_{\rm PT}$ is either below $2\,n_s$ (corresponding to masses $\lesssim1\,M_\odot$, with density jump $Δn\sim0.5\,n_s$) or, more prominently, above $4\,n_s$ (near the central density of the heaviest NS, with $Δn\sim3\,n_s$), where $n_s$ represents the nuclear saturation density. In addition, by using symmetry-energy expansion at low densities ($<1.1\,n_s$), we infer a slope parameter $L=40.2^{+19.3}_{-14.3}$ MeV, in good agreement with nuclear-experiment values. Intriguingly, $L$ correlates positively with the radius difference between $1.4\,M_\odot$ and $2.0\,M_\odot$ stars. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_10025 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Phase transition and nuclear symmetry energy from neutron star observations: Constraints in light of PSR J0614--3329 Tang, Shao-Peng Huang, Yong-Jia Fan, Yi-Zhong High Energy Astrophysical Phenomena Nuclear Theory The possible occurrence of a first-order hadron-quark phase transition (FOPT) in neutron-star interiors remains an open question. Whether such a transition can be directly tested with improved observations is a key challenge. Here, we incorporate the latest constraints, especially a new NICER radius measurement for PSR J0614--3329, into a nonparametric Gaussian Process (GP) EOS framework that explicitly includes a first-order transition. We find a Bayes factor of $B\approx2.3$ when comparing models with and without an explicit phase transition, marginally favoring its presence. At $68\%$ credibility, the transition onset density $n_{\rm PT}$ is either below $2\,n_s$ (corresponding to masses $\lesssim1\,M_\odot$, with density jump $Δn\sim0.5\,n_s$) or, more prominently, above $4\,n_s$ (near the central density of the heaviest NS, with $Δn\sim3\,n_s$), where $n_s$ represents the nuclear saturation density. In addition, by using symmetry-energy expansion at low densities ($<1.1\,n_s$), we infer a slope parameter $L=40.2^{+19.3}_{-14.3}$ MeV, in good agreement with nuclear-experiment values. Intriguingly, $L$ correlates positively with the radius difference between $1.4\,M_\odot$ and $2.0\,M_\odot$ stars. |
| title | Phase transition and nuclear symmetry energy from neutron star observations: Constraints in light of PSR J0614--3329 |
| topic | High Energy Astrophysical Phenomena Nuclear Theory |
| url | https://arxiv.org/abs/2507.10025 |