2025/01/20 by Abhijnan Kar, Kar, Abhijnan, Pulkit Ojha +3 · 1 citation
Earth and Planetary Sciences · Engineering · Physics and Astronomy · #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Geophysics and Gravity Measurements #Geophysics and Sensor Technology #High Energy Astrophysical Phenomena (astro-ph.HE) #Pulsars and Gravitational Waves Research #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2501.11475
openalex publication_date 2025/01/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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 (∼7×106 yr) LMXB and constrain the current NS mass to ∼ 1.4-1.6~\rm M_\odot. Our computations reveal a rapid B decay, with the maximum current value of ∼ 1.8×108 G, which can be useful to constrain the decay models. Note that the maximum current ν value is ∼ 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 ∼ 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 ∼ (2-3)×1037 g cm2, corresponding to a CW strain of ∼ 10-26. Our estimation of current ν values can improve the CW search sensitivity.