Smooth Light Curves from a Bumpy Ride [electronic resource] : Relativistic Blast Wave Encounters a Density Jump.
Astrophysics,astro.
Saved in:
| Online Access: |
Online Access |
|---|---|
| Corporate Author: | |
| Format: | Government Document Electronic eBook |
| Language: | English |
| Published: |
Washington, D.C : Oak Ridge, Tenn. :
United States. Dept. of Energy ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy,
2006.
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| Subjects: |
MARC
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| 245 | 0 | 0 | |a Smooth Light Curves from a Bumpy Ride |h [electronic resource] : |b Relativistic Blast Wave Encounters a Density Jump. |
| 260 | |a Washington, D.C : |b United States. Dept. of Energy ; |a Oak Ridge, Tenn. : |b distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, |c 2006. | ||
| 300 | |a 16 pages : |b digital, PDF file. | ||
| 336 | |a text |b txt |2 rdacontent. | ||
| 337 | |a computer |b c |2 rdamedia. | ||
| 338 | |a online resource |b cr |2 rdacarrier. | ||
| 500 | |a Published through the Information Bridge: DOE Scientific and Technical Information. | ||
| 500 | |a 06/06/2006. | ||
| 500 | |a "slac-pub-11889" | ||
| 500 | |a "astro-ph/0606011" | ||
| 500 | |a FT. | ||
| 500 | |a Granot, Jonathan; Nakar, Ehud. | ||
| 520 | 3 | |a Some gamma-ray burst (GRB) afterglow light curves show significant variability, which often includes episodes of rebrightening. Such temporal variability had been attributed in several cases to large fluctuations in the external density, or density ''bumps''. Here we carefully examine the effect of a sharp increase in the external density on the afterglow light curve by considering, for the first time, a full treatment of both the hydrodynamic evolution and the radiation in this scenario. To this end we develop a semi-analytic model for the light curve and carry out several elaborate numerical simulations using a one dimensional hydrodynamic code together with a synchrotron radiation code. Two spherically symmetric cases are explored in detail--a density jump in a uniform external medium, and a wind termination shock. The effect of density clumps is also constrained. Contrary to previous works, we find that even a very sharp (modeled as a step function) and large (by a factor of a >> 1) increase in the external density does not produce sharp features in the light curve, and cannot account for significant temporal variability in GRB afterglows. For a wind termination shock, the light curve smoothly transitions between the asymptotic power laws over about one decade in time, and there is no rebrightening in the optical or X-rays that could serve as a clear observational signature. For a sharp jump in a uniform density profile we find that the maximal deviation Δα{sub max} of the temporal decay index α from its asymptotic value (at early and late times), is bounded (e.g, Δα{sub max} < 0.4 for α = 10); Δα{sub max} slowly increases with α, converging to Δα{sub max} ≈ 1 at very large α values. Therefore, no optical rebrightening is expected in this case as well. In the X-rays, while the asymptotic flux is unaffected by the density jump, the fluctuations in α are found to be comparable to those in the optical. Finally, we discuss the implications of our results for the origin of the observed fluctuations in several GRB afterglows. | |
| 520 | 0 | |a Astrophysics,astro. | |
| 536 | |b AC02-76SF00515. | ||
| 650 | 7 | |a Fluctuations. |2 local. | |
| 650 | 7 | |a Radiations. |2 local. | |
| 650 | 7 | |a Afterglow. |2 local. | |
| 650 | 7 | |a Synchrotron Radiation. |2 local. | |
| 650 | 7 | |a Hydrodynamics. |2 local. | |
| 650 | 7 | |a Decay. |2 local. | |
| 650 | 7 | |a Origin. |2 local. | |
| 650 | 7 | |a Particle Accelerators. |2 edbsc. | |
| 710 | 2 | |a Stanford Linear Accelerator Center. |4 res. | |
| 710 | 1 | |a United States. |b Department of Energy. |4 spn. | |
| 710 | 1 | |a United States. |b Department of Energy. |b Office of Scientific and Technical Information. |4 dst. | |
| 856 | 4 | 0 | |u http://www.osti.gov/servlets/purl/883272-AKVwu9/ |z Online Access |
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| 952 | f | f | |p Can circulate |a University of Colorado Boulder |b Online |c Online |d Online |e E 1.99:slac-pub-11889 |h Superintendent of Documents classification |i web |n 1 |