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 derive light curves of the afterglow emission from highly collimated jetsif the power-law index ($p$) of the electron energy distribution is above 1 butbelow 2. We find (1) below the characteristic synchrotron frequency, the lightcurve index depends generally on $p$. (2) As long as the jet expansion isspherical, the light curve index above the characteristic frequency increasesslowly as the spectral index of the emission increases. (3) Once the jet entersthe spreading phase, the high-frequency emission flux decays as $\proptot^{-(p+6)/4}$ rather than $\propto t^{-p}$. All these results differ from thosein the case of $p>2$. We compare our analytical results with the observationson the GRB 010222 afterglow, and conclude that the jet model may be unable toexplain the observed data. Thus, a more promising explanation for thisafterglow seems to be the expansion of a relativistic fireball or a mildlycollimated jet in a dense medium.Comment: shortened version accepted for publication in ApJ Letter

Afterglow Emission from Highly Collimated Jets with Flat Electron Spectra: Application to the GRB 010222 Case?