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Research in Astronomy and Astrophysics 2024年第6期24卷 227-235页

作者： Xue-Feng Lu Li-Ming Song Ming-Yu Ge Shuang-Nan Zhang Jin-Lu Qu Ce Cai Cong-Zhan Liu Cheng-Kui Li Yu-Cong Fu Ying-Chen Xu Key Laboratory of Particle Astrophysics Institute of High Energy Physics University of Chinese Academy of Sciences Chinese Academy of Sciences College of Physics and Hebei Key Laboratory of Photophysics Research and Application Hebei Normal University Department of Astronomy Beijing Normal University

In October 2022, the magnetar SGR J1935+2154 entered the active outburst state. During the episode, the InsightHXMT satellite carried out a long observation that lasted for 20 days. More than 300 bursts were detected, and a certain amount of persistent radiation signals were also accumulated. This paper mainly introduces the results of persistent radiation profile folding and period search based on Insight-HXMT data. At the same time, the burst phase distribution characteristics, spectral lag results of burst, the spectral characteristics of zero-lag bursts and the time-resolved spectral evolution characteristics of high-flux bursts are reported. We found that there is no significant delay feature during different energy bands for the bursts of SGR J1935+2154. The observed zero-lag burst does not have a unique spectrum. The time-resolved spectrum of the individual burst has consistent spectral types and spectral parameters at different time periods of the burst. We also find that the burst number phase distribution and the burst photon phase distribution have the same tendency to concentrate in specific regions of the persistent emission profile.

关键词： dense matter magnetic fields radiation mechanisms: general

Estimation of transport coefficients of dense hadronic and quark matter

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Chinese Physics C 2023年第4期47卷 212-223页

作者： Debashree Sen Naosad Alam Sabyasachi Ghosh Physics Group Variable Energy Cyclotron Centre1/AF Bidhan NagarKolkata 700064India Department of Nuclear and Atomic Physics Tata Institute of Fundamental ResearchHomi Bhabha RoadMumbai 400005India Indian Institute of Technology Bhilai GEC CampusSejbaharRaipur 492015ChhattisgarhIndia

In this study,we calculated transport coefficients including the shear viscosity and electrical conductivity relative to the density of dense hadronic and quark matter.By considering the simple massless limit for the quark matter and two different effective models for the hadronic matter,we estimated the transport coefficients of the two phases separately.Accordingly,density profiles of the transport coefficients were depicted in two parts:the phasespace part and the relaxation time part.From calculating the shear viscosity to density ratio,we also explored the nearly perfect fluid domain of the quark and hadronic matter.

关键词： transport coefficients shear viscosity electrical conductivity dense matter

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What Can the Redshift Observed in EXO 0748-676 Tell Us?

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Chinese Journal of Astronomy and Astrophysics 2003年第1期3卷 33-37页

作者： Ren-Xin XuDepartment of Astronomy, School of Physics, Peking University, Beijing 100871 rxxu@*** Department of Astronomy School of Physics Peking University Beijing 100871 China

The mass-radius relations for bare and crusted strange stars are calculated with the bag model. Comparing these relations with the observed one derived from the redshift of EXO 0748–676, we come to the conclusion that it is incorrect to say that EXO 0748–676 cannot be a strange star. Various strange star models can show that EXO 0748–676 could have a mass of (1.3 ~ 1.7)M☉ and a radius of (8.4 ~ 11.4) km. It is proposed that a proportion of nascent strange stars could be bare and have masses ~ 0.1M☉, and their masses increased over a long period of accretion.

关键词： stars: fundamental parameters dense matter stars: neutron

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Merging strangeon stars Ⅱ:the ejecta and light curves

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Research in Astronomy and Astrophysics 2021年第10期21卷 86-96页

作者：来小禹夏铖君俞云伟徐仁新 Department of Physics and Astronomy Hubei University of EducationWuhan 430205China Research Center for Astronomy Hubei University of EducationWuhan 430205China School of Information Science and Engineering NingboTech UniversityNingbo 315100China Institute of Astrophysics Central China Normal UniversityWuhan 430079China School of Physics Peking UniversityBeijing 100871China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China

The state of supranuclear matter in compact stars remains puzzling,and it is argued that pulsars could be strangeon stars.The consequences of merging double strangeon stars are worth exploring,especially in the new era of multi-messenger astronomy.To develop the"strangeon kilonova"scenario proposed in Paper I,we make a qualitative description about the evolution of ejecta and light curves for merging double strangeon stars.In the hot environment of the merger,the strangeon nuggets ejected by tidal disruption and hydrodynamical squeezing would suffer from evaporation,in which process particles,such as strangeons,neutrons and protons,are emitted.Taking into account both the evaporation of strangeon nuggets and the decay of strangeons,most of the strangeon nuggets would turn into neutrons and protons,within dozens of milliseconds after being ejected.The evaporation rates of different particles depend on temperature,and we find that the ejecta could end up with two components,with high and low opacity respectively.The high opacity component would be in the directions around the equatorial plane,and the low opacity component would be in a broad range of angular directions.The bolometric light curves show that the spin-down power of the long-lived remnant would account for the whole emission of kilonova AT2017gfo associated with GW170817,if the total ejected mass 10^(-3)M⊙.The detailed picture of merging double strangeon stars is expected to be tested by future numerical simulations.

关键词： dense matter equation of state pulsars:general

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