伽马暴GRB 221009A的观测角限制OA北大核心CSTPCD

Long gamma-ray burst(GRB)GRB 221009A,known as the"rightest-of-all-time"(BOAT),triggered all satellites equipped for transient detection in all wavelengths.Relative to other GRBs ever detected by the humanity in the past half century,the fluence and peak flux of GRB 221009A are the highest.At a redshift of z=0.151,GRB 221009A holds the record of the highest ever measured isotropic energy Eiso.Prompt gamma-ray emission is thought to be the result of a highly relativistic and collimated jet with a small inclination angle with respect to the Earth.Thus,the measured isotropic energy may depends on the intrinsic energy of the jet,the opening angle of the jet,and the viewing angle of the relative jet.Here we use the relations Ep,i-Eiso and Γ-Eiso of the long burst to determine the viewing angle θ′obs and the Lorentz factor Γ of long GRB 221009.Our results show Γ=(4.23±2.81)×103 and θ′obs=0.03°±0.01°for long GRB 221009A.The result indicates that for GRB 221009A,the viewing angle between the line of sight and the jet edge of GRB 221009A is very small.That is,GRB 221009A may be a positive axis observation,which may be one of the reasons that GRB 221009A has the highest Eiso.