SIMBAD references

Sco X-1 is the brightest observed extrasolar 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 M_⊙. 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 cutoff frequency of ∼730 Hz, and perhaps even the NS breakup 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.