Early GeV afterglows from gamma-ray bursts in pulsar wind bubbles

Abstract

Gamma-ray bursts may occur within pulsar wind bubbles (PWBs) under a number of scenarios, such as the supranova-like models in which the progenitor pulsar drives a powerful wind shocking against the ambient medium before it comes to death and produces a fireball. We here study the early afterglow emission from GRBs expanding into such a PWB environment. Different from the usual cold GRB external medium, the PWBs consist of a hot electron-positron medium with typical 'thermal' Lorentz factor of the order of gamma_w, the Lorentz factor of the pulsar particle wind. After GRB blast waves shock these hot electron-positron pairs, they will emit synchrotron radiation peaking at GeV bands. It is shown that GeV photons suffer negligible absorption by the soft photons radiation field in PWBs. Thus, strong GeV emissions in the early afterglow phases are expected, providing a plausible explanation for the long-duration GeV emission from GRB940217 detected by EGRET. Future GLAST may have the potential to test this GRB-PWB interaction model.

12 pages, two missing references added, MNRAS, in press

References in corpus (5)

• High Energy Spectral Components in Gamma-Ray Burst Afterglows
• Discovery of a Transient Absorption Edge in the X-ray Spectrum of GRB 990705
• Gamma-Ray Burst Afterglows in Pulsar-Wind Bubbles
• Chandra observations of the pulsar wind nebula in SNR G0.9+0.1
• Transient Absorption Features in GRBs and Their Implications for GRB Progenitors

Cited by in corpus (4)

• Gamma-Ray Bursts: Progress, Problems & Prospects
• Constraining the origin of TeV photons from gamma-ray bursts with delayed MeV-GeV emission formed by interaction with cosmic infrared/microwave background photons
• Observational Implications of a Plerionic Environment for GRBs
• Testing the Possible Intrinsic Origin of the Excess of Very Strong MgII Absorbers Along GRB Lines-of-Sight