主要内容:
结论是upcoming Cherenkov Telescope Array (CTA)可能在二三十个月里看到一个事例。
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- · arXiv e-print (arXiv:1201.0010)
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| Title: |
| IACT observations of gamma-ray bursts: prospects for the Cherenkov Telescope Array |
| Authors: |
| Gilmore, Rudy C.; Bouvier, Aurelien; Connaughton, Valerie; Goldstein, Adam; Otte, Nepomuk; Primack, Joel R.; Williams, David A. |
| Publication: |
| eprint arXiv:1201.0010 |
| Publication Date: |
| 12/2011 |
| Origin: |
| ARXIV |
| Keywords: |
| Astrophysics - High Energy Astrophysical Phenomena |
| Comment: |
| 28 pages, 27 figures, 5 tables, submitted to MNRAS on 12/26/11 |
| Bibliographic Code: |
| 2012arXiv1201.0010G |
Abstract
Gamma rays at rest frame energies as high as 90 GeV have been reported from gamma-ray bursts (GRBs) by the Fermi Large Area Telescope (LAT). There is considerable hope that a confirmed GRB detection will be possible with the upcoming Cherenkov Telescope Array (CTA), which will have a larger effective area and better low-energy sensitivity than current imaging atmospheric Cherenkov telescopes (IACTs) such at VERITAS, MAGIC, and H.E.S.S. To estimate the likelihood of such a detection, we develop a phenomenological model for GRB emission between 1 GeV and 1 TeV. Motivated by the GRBs detected with Fermi-LAT, we consider two possible ways to extrapolate the statistics of GRBs seen by lower energy instruments. The performance characteristics of CTA are not firmly determined at this time, but we have considered two approximations for the effective area functions of the large- and medium-sized telescope arrays: first a conservative best estimate of the telescope properties, and the other intended to represent the largest effective area and lowest energy threshold that could reasonably be expected. We show a number of statistics for detected GRBs, and describe how our results could vary based on a number of parameters, such as the typical observation delay between the burst onset and the start of ground observations. We also consider the possibility of using GBM on Fermi as a finder of GRBs for rapid ground follow-up, and discuss strategies for dealing with the problematic uncertainty in GBM localization. Overall, our results indicate that CTA should be able to detect one GRB every 20 to 30 months with our baseline instrument model, assuming consistently rapid pursuit of GRB alerts, and provided that spectral breaks below about 100 GeV are not a common feature of the bright GRB population. With the more optimistic instrument model, the detection rate can be 1 to 2 GRBs per year.
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