LATEST NEWS

Comparison of gravitational waves from central engines of gamma-ray bursts: neutrino-dominated accretion flows, Blandford-Znajek mechanisms, and millisecond magnetars

Tong Liu, Chao-Yang Lin, Cui-Ying Song, and Ang Li

Neutrino-dominated accretion flow (NDAF) around a rotating stellar-mass black hole (BH) is one of the plausible candidates for the central engines of gamma-ray bursts (GRBs). Because the time-variant and anisotropic emission of neutrinos from NDAFs leads to GRB variability, NDAFs can be regarded as the sources of the strong gravitational waves (GWs). We calculate the dependences of the GW strains on both the BH spin and the accretion rate. We demonstrate that for typical GRBs with either single pulse or multiple pulses, the GWs from NDAFs might be detected at a distance of ~ 100 kpc / ~ 1 Mpc by advanced LIGO/Einstein Telescope with a typical frequency of ~ 10-100 Hz...

Neutrino-dominated accretion flows as the central engine of gamma-ray bursts (accepted for publication in New Astronomy Reviews)

Neutrino-dominated accretion flows (NDAFs) around rotating stellar-mass black holes (BHs) are plausible candidates for the central engines of gamma-ray bursts (GRBs). NDAFs are hyperaccretion disks with accretion rates in the range of around 0.001-10 M s−1, which have high density and temperature and therefore are extremely optically thick and geometrically slim or even thick. We review the theoretical progresses in studying the properties of NDAFs as well as their applications to the GRB phenomenology ...

New equation of states for postmerger supramassive quark stars

Author: Ang Li* (XMU), Zhen-Yu Zhu (XMU), and Xia Zhou (XAO-CAS)
arXiv:1706.04720, ApJ (2017) accepted

Binary neutron star (NS) mergers with their subsequent fast-rotating supramassive magnetars are one attractive interpretation for at least some short gamma-ray bursts (SGRBs), based on the internal plateau commonly observed in the early X-ray afterglow. The rapid decay phase in this scenario signifies the epoch when the star collapses to a black hole after it spins down, and could effectively shed light on the underlying unclear equation of state (EoS) of dense matter . In the present work, we confront the protomagnetar masses of the internal plateau sample from representative EoS models, with the one independently from the observed galactic NS-NS binary, aiming to contribute new compact star EoSs from SGRB observations ...

Vertical Structure of Radiation-pressure-dominated Thin Disks: Link between Vertical Advection and Convective Stability

Author: Hong-Yu Gong and Wei-Min Gu

Abstract: In the classic picture of standard thin accretion disks, viscous heating is balanced by radiative cooling through the diffusion process, and the radiation-pressure-dominated inner disk suffers convective instability. However, recent simulations have shown that, owing to the magnetic buoyancy, the vertical advection process can significantly contribute to energy transport...

Nanqiang seminar: In Search of Our Cosmic Origins

Title: In Search of Our Cosmic Origins

Speaker: Asso. Prof. Jonathan C. Tan
Institute: University of Florida
Time: 2017.4.17(Monday) 14:30
Place: Teaching Building 302, Haiyun Campus, Xiamen University

Vertical Advection Effects on Hyper-accretion Disks and Potential Link between Gamma-Ray Bursts and Kilonovae

Authors: Tuan Yi, Wei-Min Gu, Feng Yuan, Tong Liu, and Hui-Jun Mu

Recent simulations on super-Eddington accretion flows have shown that, apart from the diffusion process, the vertical advection based on magnetic buoyancy can be a more efficient process to release the trapped photons in the optically thick disk. As a consequence, the radiative luminosity from the accretion disk can be far beyond the Eddington value. Following this spirit, we revisit the structure and radiation of hyper-accretion disks with mass accretion rates in the range of 10-3〜10 Ms-1...

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