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Z. G. Dai

Publications and source records attributed to Z. G. Dai.

238 records · Page 14Linked to original sources
arXiv1998

Is GRO J1744-28 a Strange Star?

The unusal hard x-ray burster GRO J1744-28 recently discovered by the Compton Gamma-ray Observatory (GRO) can be modeled as a strange star with a dipolar magnetic field $\le 10^{11} $Gauss. When the accreted mass of the star exceeds some critical mass, its crust may break, resulting in conversion of the accreted matter into strange matter and release of energy. Subsequently, a fireball may form and expand relativistically outward. The expanding fireball may interact with the surrounding interstellar medium, causing its kinetic energy to be radiated in shock waves, producing a burst of x-ray radiation. The burst energy, duration, interval and spectrum derived from such a model are consistent with the observations of GRO J1744-28.

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arXiv1997

Gravitational Waves from Phase Transition of Accreting Neutron Stars

We propose that when neutron stars in low-mass X-ray binaries accrete sufficient mass and become millisecond pulsars, the interiors of these stars may undergo phase transitions, which excite stellar radial oscillations. We show that the radial oscillations will be mainly damped by gravitational-wave radiation instead of internal viscosity. The gravitational waves can be detected by the advanced Laser Interferometer Gravitational-Wave Observatory at a rate of about three events per year.

astro-ph↗
arXiv1997

A New Model for Soft Gamma-Ray Repeaters

We consider a model in which the soft gamma-ray repeaters (SGRs) result from young, magnetized strange stars with superconducting cores. As such a strange star spins down, the quantized vortex lines move outward and drag the magnetic field tubes because of the strong coupling between them. Since the terminations of the tubes interact with the stellar crust, the dragged tubes can produce sufficient tension to crack the crust. Part of the broken platelet will be dragged into the quark core, which is only $10^4$ cm from the surface, leading to the deconfinement of crustal matter into strange quark matter and thus the release of energy. We will show that the burst energy, duration, time interval and spectrum for our model are in agreement with the observational results. The persistent X-ray emission from the SGRs can be well explained by our model.

astro-ph↗