# Constraining the mass and moment of inertia of neutron stars from quasi-periodic oscillations in X-ray binaries - Astrophysics > High Energy Astrophysical Phenomena

Constraining the mass and moment of inertia of neutron stars from quasi-periodic oscillations in X-ray binaries - Astrophysics > High Energy Astrophysical Phenomena - Download this document for free, or read online. Document in PDF available to download.

Abstract: Neutron stars are the densest objects known in the Universe. Being the finalproduct of stellar evolution, their internal composition and structure israther poorly constrained by measurements.It is the purpose of this paper to put some constrains on the mass and momentof inertia of neutron stars based on the interpretation of kHz quasi-periodicoscillations observed in low mass X-ray binaries.We use observations of high-frequency quasi-periodic observations HF-QPOsin low mass X-ray binaries LMXBs to look for the average mass and moment ofinertia of neutron stars. This is done by applying our parametric resonancemodel to discriminate between slow and fast rotators.We fit our model to data from ten LMXBs for which HF-QPOs have been seen andthe spin of the enclosed accreting neutron star is known. For a simplifiedanalysis we assume that all neutron stars possess the same properties samemass $M *$ and same moment of inertia $I *$. We find an average mass $M *\approx 2.0-2.2\, M {\odot}$. The corresponding average moment of inertia isthen $I * \approx 1-3 \times 10^{38}\;{ m kg\,m^2} \approx 0.5-1.5 \,10\;\textrm{ km}^2 \, M \odot$ which equals to dimensionless spin parameter$\tilde{a} \approx 0.05-0.15$ for slow rotators neutron stars with a spinfrequency roughly about 300~Hz respectively $\tilde{a} \approx 0.1-0.3$ forfast rotators neutron stars with the spin frequency roughly about 600~Hz.

Author: ** J. Petri**

Source: https://arxiv.org/