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| Autores principales: | , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| Acceso en línea: | https://arxiv.org/abs/2501.11475 |
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| _version_ | 1866916577033584640 |
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| author | Kar, Abhijnan Ojha, Pulkit Bhattacharyya, Sudip |
| author_facet | Kar, Abhijnan Ojha, Pulkit Bhattacharyya, Sudip |
| contents | Sco X-1 is the brightest observed extra-solar X-ray source, which is a neutron star (NS) low-mass X-ray binary (LMXB), and is thought to have a strong potential for continuous gravitational waves (CW) detection due to its high accretion rate and relative proximity. Here, we compute the long-term evolution of its parameters, particularly the NS spin frequency ($ν$) and the surface magnetic field ($B$), to probe its nature and its potential for CW detection. We find that Sco X-1 is an unusually young ($\sim7\times10^6$ yr) LMXB and constrain the current NS mass to $\sim 1.4-1.6~{\rm M}_\odot$. Our computations reveal a rapid $B$ decay, with the maximum current value of $\sim 1.8\times10^8$ G, which can be useful to constrain the decay models. Note that the maximum current $ν$ value is $\sim 550$ Hz, implying that, unlike what is generally believed, a CW emission is not required to explain the current source properties. However, $ν$ will exceed an observed cut-off frequency of $\sim 730$ Hz, and perhaps even the NS break-up frequency, in the future, without a CW emission. The minimum NS mass quadrupole moment ($Q$) to avoid this is $\sim (2-3)\times10^{37}$ g cm$^2$, corresponding to a CW strain of $\sim 10^{-26}$. Our estimation of current $ν$ values can improve the CW search sensitivity. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_11475 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Long-term evolution of Sco X-1: implications for the current spin frequency and ellipticity of the neutron star Kar, Abhijnan Ojha, Pulkit Bhattacharyya, Sudip High Energy Astrophysical Phenomena Solar and Stellar Astrophysics General Relativity and Quantum Cosmology Sco X-1 is the brightest observed extra-solar X-ray source, which is a neutron star (NS) low-mass X-ray binary (LMXB), and is thought to have a strong potential for continuous gravitational waves (CW) detection due to its high accretion rate and relative proximity. Here, we compute the long-term evolution of its parameters, particularly the NS spin frequency ($ν$) and the surface magnetic field ($B$), to probe its nature and its potential for CW detection. We find that Sco X-1 is an unusually young ($\sim7\times10^6$ yr) LMXB and constrain the current NS mass to $\sim 1.4-1.6~{\rm M}_\odot$. Our computations reveal a rapid $B$ decay, with the maximum current value of $\sim 1.8\times10^8$ G, which can be useful to constrain the decay models. Note that the maximum current $ν$ value is $\sim 550$ Hz, implying that, unlike what is generally believed, a CW emission is not required to explain the current source properties. However, $ν$ will exceed an observed cut-off frequency of $\sim 730$ Hz, and perhaps even the NS break-up frequency, in the future, without a CW emission. The minimum NS mass quadrupole moment ($Q$) to avoid this is $\sim (2-3)\times10^{37}$ g cm$^2$, corresponding to a CW strain of $\sim 10^{-26}$. Our estimation of current $ν$ values can improve the CW search sensitivity. |
| title | Long-term evolution of Sco X-1: implications for the current spin frequency and ellipticity of the neutron star |
| topic | High Energy Astrophysical Phenomena Solar and Stellar Astrophysics General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2501.11475 |