Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of p and Structure of the Circumburst Medium
We constrain blast wave parameters and the circumburst media of a subsample of 10 BeppoSAX gamma-ray bursts(GRBs). For this sample we derive the values of the injected electron energy distribution index, p, and the densitystructure index of the circumburst medium, k, from simultaneous spectral fits...
| Main Authors: | , , , , , , , |
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| Format: | Journal Article |
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Institute of Physics Publishing, Inc.
2008
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| Online Access: | http://iopscience.iop.org/0004-637X/672/1/433/pdf/71979.web.pdf http://hdl.handle.net/20.500.11937/23089 |
| _version_ | 1848751052756615168 |
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| author | Starling, R. van der Horst, A. Rol, E. Wijers, R. Kouveliotou, C. Wiersema, K. Curran, Peter Weltevrede, P. |
| author_facet | Starling, R. van der Horst, A. Rol, E. Wijers, R. Kouveliotou, C. Wiersema, K. Curran, Peter Weltevrede, P. |
| author_sort | Starling, R. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We constrain blast wave parameters and the circumburst media of a subsample of 10 BeppoSAX gamma-ray bursts(GRBs). For this sample we derive the values of the injected electron energy distribution index, p, and the densitystructure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical, and NIR afterglowdata. The spectral fits have been done in count space and include the effects of metallicity, and are comparedwith the previously reported optical and X-ray temporal behavior. Using the blast wave model and some assumptionswhich include on-axis viewing and standard jet structure, constant blast wave energy, and no evolution of themicrophysical parameters, we find a mean value of p for the sample as a whole of 2:04þ0:020:03. A statistical analysis ofthe distribution demonstrates that the p-values in this sample are inconsistent with a single universal value for p at the3 level or greater, which has significant implications for particle acceleration models. This approach provides uswith a measured distribution of circumburst density structures rather than considering only the cases of k ¼ 0 (homogeneous)and k ¼ 2 (windlike).We find five GRBs for which k can be well constrained, and in four of these cases thecircumburst medium is clearly windlike. The fifth source has a value of 0 k 1, consistent with a homogeneouscircumburst medium. |
| first_indexed | 2025-11-14T07:46:36Z |
| format | Journal Article |
| id | curtin-20.500.11937-23089 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T07:46:36Z |
| publishDate | 2008 |
| publisher | Institute of Physics Publishing, Inc. |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-230892017-02-28T01:37:24Z Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of p and Structure of the Circumburst Medium Starling, R. van der Horst, A. Rol, E. Wijers, R. Kouveliotou, C. Wiersema, K. Curran, Peter Weltevrede, P. gamma rays: bursts We constrain blast wave parameters and the circumburst media of a subsample of 10 BeppoSAX gamma-ray bursts(GRBs). For this sample we derive the values of the injected electron energy distribution index, p, and the densitystructure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical, and NIR afterglowdata. The spectral fits have been done in count space and include the effects of metallicity, and are comparedwith the previously reported optical and X-ray temporal behavior. Using the blast wave model and some assumptionswhich include on-axis viewing and standard jet structure, constant blast wave energy, and no evolution of themicrophysical parameters, we find a mean value of p for the sample as a whole of 2:04þ0:020:03. A statistical analysis ofthe distribution demonstrates that the p-values in this sample are inconsistent with a single universal value for p at the3 level or greater, which has significant implications for particle acceleration models. This approach provides uswith a measured distribution of circumburst density structures rather than considering only the cases of k ¼ 0 (homogeneous)and k ¼ 2 (windlike).We find five GRBs for which k can be well constrained, and in four of these cases thecircumburst medium is clearly windlike. The fifth source has a value of 0 k 1, consistent with a homogeneouscircumburst medium. 2008 Journal Article http://hdl.handle.net/20.500.11937/23089 http://iopscience.iop.org/0004-637X/672/1/433/pdf/71979.web.pdf Institute of Physics Publishing, Inc. restricted |
| spellingShingle | gamma rays: bursts Starling, R. van der Horst, A. Rol, E. Wijers, R. Kouveliotou, C. Wiersema, K. Curran, Peter Weltevrede, P. Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of p and Structure of the Circumburst Medium |
| title | Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of p and Structure of the Circumburst Medium |
| title_full | Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of p and Structure of the Circumburst Medium |
| title_fullStr | Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of p and Structure of the Circumburst Medium |
| title_full_unstemmed | Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of p and Structure of the Circumburst Medium |
| title_short | Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of p and Structure of the Circumburst Medium |
| title_sort | gamma-ray burst afterglows as probes of environment and blast wave physics. ii. the distribution of p and structure of the circumburst medium |
| topic | gamma rays: bursts |
| url | http://iopscience.iop.org/0004-637X/672/1/433/pdf/71979.web.pdf http://hdl.handle.net/20.500.11937/23089 |