Experimental search for gamma-ray bursts from evaporating primordial black holes
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ARTICLES, FIELDS, GRAVITATION, AND ASTROPHYSICS
Experimental Search for GammaRay Bursts from Evaporating Primordial Black Holes V. B. Petkova,b, E. V. Bugaeva, P. A. Klimaia*, M. V. Andreeva,b,c, V. I. Volchenkoa, G. V. Volchenkoa, I. M. Dzaparovaa,b, D. D. Dzhappueva, A. N. Gaponenkoa, Zh. Sh. Gulieva, N. F. Klimenkoa, A. U. Kudzhaeva, A. V. Sergeeva,b,c, N. S. Khaerdinova, A. B. Chernyaeva, and A. F. Yanina a
Institute for Nuclear Research, Russian Academy of Sciences, ul. 60letiya Oktyabrya 7a, Moscow, 117312 Russia bTerskol Branch of the Institute of Astronomy, Russian Academy of Sciences, Terskol, 361605 Russia c International Center for Astronomical and Medicoecological Research, National Academy of Sciences of Ukraine, Ukraine *email: [email protected] Received June 29, 2009
Abstract—The energy spectra and temporal characteristics of highenergy gammaray bursts from evaporat ing primordial black holes have been calculated using various evaporation models. The currently existing the oretical uncertainties in the shape of the evaporated photon spectrum are discussed. The data from the Andyrchy and Carpet2 arrays of the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) obtained in the mode of detection of a single cosmicray component are used to search for cosmic gammaray bursts with a primary photon energy of about 8 GeV. New upper limits have been obtained for the number density of evaporating black holes in a local region of space with a characteristic size of ~10–3 pc for various evaporation models. DOI: 10.1134/S1063776110030040
1. INTRODUCTION Primordial black holes (PBHs) could be formed in the early Universe through the gravitational collapse of primordial cosmological density fluctuations— those that gave rise to the observed structure of the Universe (galaxies and clusters of galaxies) during its subsequent evolution. For an appreciable number of PBHs to be formed, it is important that significant density fluctuations on small mass scales existed in the early Universe. The curvature fluctuations and the related density fluctuations are currently believed to result from an inflationary expansion of the Universe; significantly, the power spectrum of these fluctuations is entirely determined by the parameters of the theo retical inflation model used and primarily by the form of the inflation potential. There exist quite a few mod els (see, e.g., [1] and references therein) in which a fluctuation spectrum that ensures the formation of a considerable number of PBHs is predicted. Thus, whether PBHs exist or not is an experimental question. Their detection will provide valuable infor mation about the processes in the early Universe, pri marily about the patterns of inflationary expansion and formation of the now observed structure. The nondetection of PBHs at the current level of the experimental technique also carries useful informa
tion and allows further progress to be made in under standing the early Universe. Theoretical predictions of the PBH fo
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