English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We explore the implications of the light curve of the early TeV gamma-rayafterglow of GRB221009A reported by the LHAASO collaboration. We show that thereported offset of the reference time, $T_*$, allows the determination of therelativistic jet activation time, which occurs approximately $200\,\mathrm{s}$after the GBM trigger time and closely precedes the moment at which GBM wassaturated. We find that while the LHAASO data do not exclude the homogeneouscircumburst medium scenario, the progenitor wind scenario looks preferable,finding excellent agreement with the expected size of the stellar bubble. Weconclude that the initial growth of the light curve is dominated by processesinternal to the jet or by gamma-gamma attenuation on the photons emitted duringthe prompt phase. Namely, either the activation of the acceleration process orthe decrease of internal gamma-gamma absorption can naturally explain theinitial rapid flux increase. The subsequent slow flux growth phase observed upto $T_*+18\,\mathrm{s}$ is explained by the build-up of the synchrotronradiation -- the target for inverse Compton scattering, which is also supportedby a softer TeV spectrum measured during this period. The duration of thisphase allows an almost parameter-independent determination of the jet's initialLorentz factor, $\Gamma_0\approx600$, and magnetic field strength,$B'\sim0.3\,\mathrm{G}$. These values appear to match well those previouslyrevealed through spectral modeling of the GRB emission.

Naked forward shock seen in the TeV afterglow data of GRB221009A