Speaker
Prof.
Zhen Cao
Description
LHAASO observed GRB221009A, as the brightest GRB, with it nearly in the middle of the FoV. The onset of the afterglow in TeV band was first time observed by measuring the flux from the GRB since T0 set by a precursor. This enables 1) Determining the start time of the afterglow T* $\sim 226$ s after T0; 2) Setting the most strict limit on the prompt emission in TeV band $\sim10^{-5}$; 3) Estimating the initial bulk Lorentz factor $\Gamma_0$ of the ejecta $\sim 440$; 4) Measuring the jet break shortly after the onset indicating a narrow jet structure observed ever; 5) Furher investigations for more GRB features, including the most energetic photons.
Primary author
Prof.
Zhen Cao
Co-author
LHAASO team
