ON THE IMPLICATIONS OF LATE INTERNAL DISSIPATION FOR SHALLOW-DECAY AFTERGLOW EMISSION AND ASSOCIATED HIGH-ENERGY GAMMA-RAY SIGNALS
- Center for Cosmology and AstroParticle Physics, Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210 (United States)
- Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)
- Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara 252-5258 (Japan)
The origin of the shallow-decay emission during early X-ray afterglows has been an open issue since the launch of the Swift satellite. One of the appealing models is the late internal dissipation model, where X-ray emission during the shallow-decay phase is attributed to internal dissipation, analogous to the prompt gamma-ray emission. We discuss possible scenarios of the late prompt emission, such as late internal shocks, magnetic reconnection, and photospheric dissipation. We also consider the consequences of late dissipation and a two-component (early and late) jet model for the high-energy (GeV-TeV) emission. We study not only synchrotron self-Compton (SSC) emission from the early and late jets but also external inverse-Compton (EIC) emission, which is naturally predicted in the late dissipation model. For the latter, we perform numerical calculations taking into account the equal-arrival-time surface of EIC photons and show that the EIC component typically has a peak at {approx}1-100 GeV which may dominate over the SSC components. We demonstrate that very high energy gamma rays from both these components are detectable for nearby and/or energetic gamma-ray bursts, with current and future Cherenkov detectors such as MAGIC, VERITAS, CTA, and HAWC, and possibly Fermi. Although the expected event rate would not be large, detections should be useful as a test of the model. Multi-wavelength observations using both the ground-based telescopes and the Swift and/or Fermi satellites are also important to constrain the models.
- OSTI ID:
- 21576883
- Journal Information:
- Astrophysical Journal, Vol. 732, Issue 2; Other Information: DOI: 10.1088/0004-637X/732/2/77; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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