Please use this identifier to cite or link to this item: http://hdl.handle.net/2445/150262
 Title: MAGIC observation of the GRB 080430 afterglow Author: Bosch i Ramon, ValentíParedes i Poy, Josep MariaRibó Gomis, Marc Keywords: Raigs gammaEsclat de raigs gammaGamma raysGamma ray bursts Issue Date: 2010 Publisher: EDP Sciences Abstract: Context: Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of gamma-ray bursts during the prompt phase, i.e. the initial burst of high-energy radiation, and during the long-lasting afterglows. In spite of many successes in interpreting these phenomena, there are still several open key questions about the fundamental emission processes, their energetics and the environment. Aim: Independently of specific gamma-ray burst theoretical recipes, spectra in the GeV/TeV range are predicted to be remarkably simple, being satisfactorily modeled with power-laws, and therefore offer a very valuable tool to probe the extragalactic background light distribution. Furthermore, the simple detection of a component at very-high energies, i.e. at $\sim 100$\,GeV, would solve the ambiguity about the importance of various possible emission processes, which provide barely distinguishable scenarios at lower energies. Methods: We used the results of the MAGIC telescope observation of the moderate resdhift ($z\sim0.76$) \object{GRB\,080430} at energies above about 80\,GeV, to evaluate the perspective for late-afterglow observations with ground based GeV/TeV telescopes. Results: We obtained an upper limit of $F_{\rm 95%\,CL} = 5.5 \times 10^{-11}$\,erg\,cm$^{-2}$\,s$^{-1}$ for the very-high energy emission of \object{GRB\,080430}, which cannot set further constraints on the theoretical scenarios proposed for this object also due to the difficulties in modeling the low-energy afterglow. Nonetheless, our observations show that Cherenkov telescopes have already reached the required sensitivity to detect the GeV/TeV emission of GRBs at moderate redshift ($z \lesssim 0.8$), provided the observations are carried out at early times, close to the onset of their afterglow phase. Note: Reproducció del document publicat a: https://doi.org/10.1051/0004-6361/200913461 It is part of: Astronomy & Astrophysics, 2010, vol. 517, p. A5 URI: http://hdl.handle.net/2445/150262 Related resource: https://doi.org/10.1051/0004-6361/200913461 ISSN: 0004-6361 Appears in Collections: Articles publicats en revistes (Física Quàntica i Astrofísica)

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