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 nature of the shallow decay phase in the X-ray afterglow of the gamma-rayburst (GRB) is not yet clarified. We analyze the data of early X-ray afterglowsof 26 GRBs triggered by Burst Alert Telescope onboard Neil Gehrels SwiftObservatory and subsequently detected by Fermi Large Area Telescope (LAT)and/or Imaging Atmospheric Cherenkov Telescopes. It is found that 9 events(including 2 out of 3 very-high-energy gamma-ray events) have no shallow decayphase and that their X-ray afterglow light curves are well described by singlepower-law model except for the jet break at later epoch. The rest are fitted bydouble power-law model and have a break in the early epoch (around ks),however, 8 events (including a very-high-energy gamma-ray event) have thepre-break decay index larger than 0.7. We also analyze the data of well-sampledX-ray afterglows of GRBs without LAT detection, and compare their decayproperties with those of high-energy and very-high-energy gamma-ray events. Itis found that for the GeV/TeV bursts, the fraction of events whose X-rayafterglows are described by single power-law is significantly larger than thosefor non GeV/TeV GRBs. Even if the GeV/TeV GRBs have shallow decay phase, theirdecay slope tends to be steeper than non GeV/TeV bursts, that is, they haveless noticeable shallow decay phase in the early X-ray afterglow. A possibleinterpretation along with the energy injection model is briefly discussed.

Less noticeable shallow decay phase in early X-ray afterglows of GeV/TeV-detected gamma-ray bursts