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 Plus annual

Presents the access of premium content as premium feature

Premium Content

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 annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The physical origin of the >0.1 GeV emission detected from Gamma-Ray Bursts(GRBs) by the Fermi satellite has not yet been completely understood. In thiswork we consider the GeV light curves of ten GRBs with measured redshiftdetected by the Fermi-LAT. These light curves are characterised by a long-lived($\gtrsim10^2$ seconds) emission, whose luminosity decays in time as apower-law. While the decay rate is similar for all GRBs (i.e. $L_{LAT}\proptot^{-1.2}$), the normalisation spans about two orders of magnitude inluminosity. However, after re-normalising the luminosities to the promptenergetics $E_{iso}$ the light curves overlap. We consider the scenario inwhich the temporally extended LAT emission is dominated by synchrotronradiation from electrons accelerated at the forward external shock. Accordingto this model, at high-energies (i.e. above the typical synchrotronfrequencies) a small dispersion of the $E_{iso}$-normalised light curves isexpected. The fact that the LAT temporally extended emission follows thisbehaviour reinforces its interpretation in terms of afterglow radiation fromexternal shocks. Assuming this scenario, we argue that the parameters$\epsilon_e$ and $\eta_\gamma$ (i.e., the fraction of shock-dissipated energygained by the electrons, and the efficiency of the mechanism producing theprompt radiation, respectively) must be narrowly distributed.

Clustering of LAT light curves: a clue to the origin of high-energy emission in Gamma-Ray Bursts