arXiv subjects

Xiao-Yu Lai

Publications and source records attributed to Xiao-Yu Lai.

3 recordsLinked to original sources

arXiv2024

Rotating massive strangeon stars and X-ray plateau of short GRBs

Strangeon stars, which are proposed to describe the nature of pulsar-like compact stars, have passed various observational tests. The maximum mass of a non-rotating strangeon star could be high, which implies that the remnants of binary strangeon star mergers could even be long-lived massive strangeon stars. We study rigidly rotating strangeon stars in the slowly rotating approximation, using the Lennard-Jones model for the equation of state. Rotation can significantly increase the maximum mass of strangeon stars with unchanged baryon numbers, enlarging the mass-range of long-lived strangeon stars. During spin-down after merger, the decrease of radius of the remnant will lead to the release of gravitational energy. Taking into account the efficiency of converting the gravitational energy luminosity to the observed X-ray luminosity, we find that the gravitational energy could provide an alternative energy source for the plateau emission of X-ray afterglow. The fitting results of X-ray plateau emission of some short gamma-ray bursts suggest that the magnetic dipole field strength of the remnants can be much smaller than that of expected when the plateau emission is powered only by spin-down luminosity of magnetars.

astro-ph.HE↗

arXiv2022

A bag model of matter condensed by the strong interaction

Inspired by various astrophysical phenomenons, it is suggested that pulsar-like compact stars are comprised entirely of strangeons (quark-clusters with three-light-flavor symmetry) and a small amount of electrons. In order to better constrain the properties of strangeon stars, we propose a linked bag model to describe the condensed matter by the strong interaction (i.e., strong condensed matter) in both 2-flavoured (nucleons) and 3-flavoured (hyperons, strangeons, etc.) scenarios. The model parameters are calibrated to reproduce the saturation properties of nuclear matter, which are later applied to hyperon matter and strangeon matter. Compared with baryon matter, the derived energy per baryon of strangeon matter is reduced if the strangeon carries a large number of valence quarks, which stiffens the equation of state and consequently increases the maximum mass of strangeon stars. In a large parameter space, the maximum mass and tidal deformability of strangeon stars predicted by the linked bag model are consistent with the current astrophysical constraints. It is found that the maximum mass of strangeon stars can be as large as $\sim 2.5M_\odot$, while the tidal deformability of a $1.4M_\odot$ strangeon star lies in the range of $180\lesssim Λ_{1.4} \lesssim 340$.

nucl-th↗

arXiv2021

Rotation and deformation of strangeon stars in the Lennard-Jones model

The strong interactions at low energy scales determine the state of the supranuclear matter in the pulsar-like compact objects. It is proposed that the bulk strong matter could be composed of strangeons, which are quark clusters with a nearly equal number of three light-flavor quarks. In this work, to characterize the strong-repulsive interactions at short distances and the non-relativistic nature of the strangeons, the Lennard-Jones model is used to describe the equation of state (EoS) of strangeon stars (SSs). We investigate the static, the slowly rotating, and the tidally deformed SSs in detail. The corrections resulted from the finite surface densities are considered crucially in the perturbative approaches. We also study the universal relations between the moments of inertia, the tidal deformabilities, and the quadrupole moments. Those results are ready to be used for various purposes in astrophysics, and possible constraints from contemporary observations on the parameter space of the Lennard-Jones model are discussed. Future observations of the pulsars' radio signals, the X-ray emissions from the hot spots on the surface of the stars, and the gravitational waves (GWs) from binary mergers can give tighter constraints or even verify or falsify the existence of SSs.

gr-qc↗