Impact on orbital period of X-ray Binary system attached to a cosmic string
Ishan Swamy, Deobrat Singh
TL;DR
The paper addresses unexplained orbital-period changes in X-ray binaries by proposing that a cosmic string attached to a spinning black hole extracts rotational energy, inducing mass loss and orbital-parameter evolution. By combining Keplerian dynamics with a mass-loss model $\\dot{m} \approx -(10^4\,M_{\odot}/\text{s})\\mu$, it derives a direct relation $\\dot{P} \approx 2P\left(\\frac{10^4\,M_{\odot}/\text{s}}{m}\\right)\\mu$, and shows consistency with observed $\\dot{P}$ values across several LMXBs that imply tensions in the range $\\mu \sim 10^{-17}$ to $10^{-18}$. The study argues that low-mass X-ray binaries offer a feasible indirect channel to detect cosmic strings and to explain rapid period changes, while noting limitations such as neglected star–string interactions and the need for future three-body modeling in higher-mass systems. Overall, the work provides a concrete, testable mechanism linking cosmic-string energy extraction to observable binary dynamics and highlights a promising observational path for cosmic string searches.
Abstract
Cosmic strings attached to rotating black holes extract its rotational energy, resulting in a mass loss and reduced spin. In this paper we discuss the proposed methods to detect these phenomena and present a novel methodology based on existing literature, by considering a Low Mass X-ray binary system. We investigate the impact of a cosmic string interacting with a black hole in an X-ray binary system and attempt to explain the observations of unexpected orbital period changes in such systems by proposing mass loss by cosmic strings to be a potential cause. For a period change of order $10^{-10}$, the string tension is $\sim 10^{-17}$, lying in the predicted range for cosmic string tension. An analysis of multiple low mass X-ray binary systems is carried out and it is shown that a significant and observable change occurs for a string tension $\sim 10^{-11}$.