The first-order phase transition in the neutron star from the deep neural network

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Hauptverfasser: Zhou, Wenjie, Shen, Hong, Hu, Jinniu, Zhang, Ying
Format: Preprint
Veröffentlicht: 2024
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author Zhou, Wenjie
Shen, Hong
Hu, Jinniu
Zhang, Ying
author_facet Zhou, Wenjie
Shen, Hong
Hu, Jinniu
Zhang, Ying
contents This study investigates the first-order phase transition within neutron stars, leveraging the deep neural network (DNN) framework alongside contemporary astronomical measurements. The equation of state (EOS) for neutron stars is delineated in a piecewise polytropic form, with the speed of sound ($c_s$) serving as a pivotal determinant. In the phase transition region, $c_s$ is presumed to be zero, while in other intervals, it is optimized utilizing the DNN. Various onset energy densities of phase transition ($\varepsilon_{pt}$), spanning from $2\varepsilon_0$ to $3\varepsilon_0$ (where $\varepsilon_0$ denotes the energy density at nuclear saturation density), as well as phase transition widths ($Δ\varepsilon$) ranging from $0.5\varepsilon_0$ to $\varepsilon_0$, are examined. Our findings underscore that smaller values of $\varepsilon_{pt}$ lead to a more substantial impact of $Δ\varepsilon$ on neutron star properties, encompassing maximum mass, corresponding radius, tidal deformability, phase transition mass, and trace anomaly. Conversely, when $\varepsilon_{pt}$ exceeds $2.5\varepsilon_0$, the influence of $Δ\varepsilon$ diminishes, resulting in a stiffer EOS compared to scenarios lacking a phase transition. Furthermore, the trace anomaly at high density shifts to negative values upon the commencement of the phase transition. It is noteworthy that the correlations between the average speed of sound at different energy density segments demonstrate a notably weak connection. The discernment of whether a phase transition has occurred with the present observables of neutron stars poses a challenging task.
format Preprint
id arxiv_https___arxiv_org_abs_2407_11447
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The first-order phase transition in the neutron star from the deep neural network
Zhou, Wenjie
Shen, Hong
Hu, Jinniu
Zhang, Ying
Nuclear Theory
High Energy Astrophysical Phenomena
This study investigates the first-order phase transition within neutron stars, leveraging the deep neural network (DNN) framework alongside contemporary astronomical measurements. The equation of state (EOS) for neutron stars is delineated in a piecewise polytropic form, with the speed of sound ($c_s$) serving as a pivotal determinant. In the phase transition region, $c_s$ is presumed to be zero, while in other intervals, it is optimized utilizing the DNN. Various onset energy densities of phase transition ($\varepsilon_{pt}$), spanning from $2\varepsilon_0$ to $3\varepsilon_0$ (where $\varepsilon_0$ denotes the energy density at nuclear saturation density), as well as phase transition widths ($Δ\varepsilon$) ranging from $0.5\varepsilon_0$ to $\varepsilon_0$, are examined. Our findings underscore that smaller values of $\varepsilon_{pt}$ lead to a more substantial impact of $Δ\varepsilon$ on neutron star properties, encompassing maximum mass, corresponding radius, tidal deformability, phase transition mass, and trace anomaly. Conversely, when $\varepsilon_{pt}$ exceeds $2.5\varepsilon_0$, the influence of $Δ\varepsilon$ diminishes, resulting in a stiffer EOS compared to scenarios lacking a phase transition. Furthermore, the trace anomaly at high density shifts to negative values upon the commencement of the phase transition. It is noteworthy that the correlations between the average speed of sound at different energy density segments demonstrate a notably weak connection. The discernment of whether a phase transition has occurred with the present observables of neutron stars poses a challenging task.
title The first-order phase transition in the neutron star from the deep neural network
topic Nuclear Theory
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2407.11447