Transient Optical Emission from a Nonstationary Accretion Disk: A Model for Optical Afterglow of Gamma Ray Bursts

Publications of the Astronomical Society of Japan

Cheng, Kwong-Sang¹  Lu, Ye²  Zhao, Gang³ 

[1] Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong, China;Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong, ChinaBeijing Astronomical Observatory, Chinese Academy of Sciences, Beijing 100012, China;Beijing Astronomical Observatory, Chinese Academy of Sciences, Beijing 100012, China

关键词: "accretion disk: instability";    "black holes";    galaxies;    "gamma-ray bursts";    "radiation mechanism";   

DOI  :  10.1093/pasj/52.4.711

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

Weconsiderthetime-dependentbehaviorofnonstationaryaccretiondiskwhichisformedbythecaptureanddisruptionofamain-sequencestararoundamassiveblackhole.Ifaninstabilityisdevelopedintheinneredgeofthenonstationarydiskandproducesastrongmagneticfield,alargeamountoftheblackholerotationalenergycanbeextractedviatheBlandford-Znajekprocess,whichresultsinaGamma-RayBurst(GRB)withatypicalduration∼10–102s.OtherparametersrelatedtoatypicalGRBincludingburstenergy,risetimeoftheburst,numberofsub-burstetcarealsoestimated.Theverticalstructureandthermalstabilitypropertiesofthediskareinvestigatedindetail.Intheearlystageofformingtransientaccretiondisk,thematerialsuppliedbythetidallydisruptedstarisclumpedintherelativelycooldisk.Thiseventuallyleadstoathermalinstability,whichresultsinanincreaseoftheviscosityofthedisk.Astheinstabilitypropagatesacrossthedisk,thestabilityofatime-dependentdiskandvariabilityofthemass-depositionrateprovideapossibleexplanationfortransientopticalemission.WespeculatethatthistransientopticalemissionfromanonstationaryaccretiondiskmayrelatetothebehaviorofGRBopticalafterglow,andthetransientopticalafterglowcanbereproducedifonetakesintoaccounttheeffectofanevolvingviscousparameter,α.

【 授权许可】

Unknown