Radial and Non-Radial Oscillations of Protoneutron Stars with Hyperonic Composition
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arXiv
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| Autori principali: | , , , , |
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| Natura: | Preprint |
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2025
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| _version_ | 1866918216436023296 |
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| author | Thakur, Prashant Issifu, Adamu Rather, Ishfaq Ahmad Lim, Y. Frederico, Tobias |
| author_facet | Thakur, Prashant Issifu, Adamu Rather, Ishfaq Ahmad Lim, Y. Frederico, Tobias |
| contents | This paper explores radial and non-radial oscillations of protoneutron stars (PNSs) as they evolve from hot, neutrino-rich configurations through deleptonization to cold, catalyzed states. The equation of state (EoS) is modeled using a density-dependent relativistic mean-field framework, with stellar evolution characterized by changes in entropy and lepton fraction. Both nucleonic and hyperonic compositions are considered. Non-radial $f$- and $p_1$-mode oscillations are computed using both the Cowling approximation and the full General Relativistic framework. Trapped neutrinos initially increase the error in the Cowling approximation for $f$-modes, which decreases during deleptonization and rises again in the cold phase. In contrast, $p_1$-mode errors peak during intermediate stages due to evolving pressure and density gradients. The emergence of hyperons modestly raises oscillation frequencies in both modes. Existing universal relations for $f$-mode frequency and damping time lack model independence for PNSs, motivating a more robust relation. In particular, our proposed universal relation involving the moment of inertia and $\tildeη$ shows strong agreement across all evolutionary phases, offering a temperature-sensitive, model-independent scaling for asteroseismology. Radial oscillations of a $1.4\,M_\odot$ PNS are also studied for different EoSs. Our results show that displacement ($ξ$) and pressure perturbation ($η$) profiles are highly sensitive to thermal state, composition, and compactness. Hyperonic stars show higher frequencies, altered node structures, and stronger pressure perturbations due to EoS softening. Differences in frequency separation $Δν_n$ and fundamental frequency $ν_0$ between nucleonic and hyperonic models provide clear observational diagnostics for probing the interiors of PNSs and constraining the EoS of dense matter. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_24104 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Radial and Non-Radial Oscillations of Protoneutron Stars with Hyperonic Composition Thakur, Prashant Issifu, Adamu Rather, Ishfaq Ahmad Lim, Y. Frederico, Tobias Nuclear Theory High Energy Astrophysical Phenomena This paper explores radial and non-radial oscillations of protoneutron stars (PNSs) as they evolve from hot, neutrino-rich configurations through deleptonization to cold, catalyzed states. The equation of state (EoS) is modeled using a density-dependent relativistic mean-field framework, with stellar evolution characterized by changes in entropy and lepton fraction. Both nucleonic and hyperonic compositions are considered. Non-radial $f$- and $p_1$-mode oscillations are computed using both the Cowling approximation and the full General Relativistic framework. Trapped neutrinos initially increase the error in the Cowling approximation for $f$-modes, which decreases during deleptonization and rises again in the cold phase. In contrast, $p_1$-mode errors peak during intermediate stages due to evolving pressure and density gradients. The emergence of hyperons modestly raises oscillation frequencies in both modes. Existing universal relations for $f$-mode frequency and damping time lack model independence for PNSs, motivating a more robust relation. In particular, our proposed universal relation involving the moment of inertia and $\tildeη$ shows strong agreement across all evolutionary phases, offering a temperature-sensitive, model-independent scaling for asteroseismology. Radial oscillations of a $1.4\,M_\odot$ PNS are also studied for different EoSs. Our results show that displacement ($ξ$) and pressure perturbation ($η$) profiles are highly sensitive to thermal state, composition, and compactness. Hyperonic stars show higher frequencies, altered node structures, and stronger pressure perturbations due to EoS softening. Differences in frequency separation $Δν_n$ and fundamental frequency $ν_0$ between nucleonic and hyperonic models provide clear observational diagnostics for probing the interiors of PNSs and constraining the EoS of dense matter. |
| title | Radial and Non-Radial Oscillations of Protoneutron Stars with Hyperonic Composition |
| topic | Nuclear Theory High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2505.24104 |