Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 0803.2313

Constraints on the Number Density of Evaporating Primordial Black Holes for the Chromospheric Evaporation Models

V. B. Petkov·E. V. Bugaev·P. A. Klimai·D. V. Smirnov
View original source ↗Read source document ↗Export metadata ↓

Abstract

Cosmic gamma-ray bursts with primary-photon energies > 10 GeV are sought in the data from the Andyrchy array obtained in the mode of detection of a single cosmic-ray component during a net observation period of 2005.4 d. The distribution of fluctuations of the detector counting rate agrees with the expected cosmic-ray background, the only exception being an event with a deviation of 7.9 sigma. Constraints on the number density of evaporating primordial black holes in a local region of the Galaxy are obtained for the chromospheric evaporation models.

Explore related subjects

astro-ph

Keep this discovery

BibTeXRIS

V. B. Petkov, E. V. Bugaev, P. A. Klimai, D. V. Smirnov. 2008-03-15. Constraints on the Number Density of Evaporating Primordial Black Holes for the Chromospheric Evaporation Models. https://doi.org/10.1007/s11448-008-1001-0

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2009

Synthesis of Taylor Phase Screens with Karhunen-Loeve Basis Functions

Phase screens above a telescope pupil represent the variation of the phase of the electromagnetic field induced by atmospheric turbulence. Instances drawn from such statistics are represented by a vector of random phase amplitudes which are coefficients of a linear superposition of two-dimensional basis functions across the pupil. This work shortly reviews Fried's analysis of this modal decomposition for the case of Kolmogorov statistics of the phase covariance as a function of separation in the pupil plane. We focus on the numerical synthesis of phase screens. The statistically independent modes are transformed into the eigen-modes of a gradient matrix as time-dependence is introduced such that on short time scales the instances of the phase screens are rigidly shifted into a direction imposed by some wind velocity - known as the Taylor frozen screen approximation. This simple technique factorizes spatial and temporal variables and aims at binding the time dependence of the phase screens to the few expansion coefficients of the basis functions that obey a stochastic time-dependent differential equation.

astro-ph↗
arXiv2009

Towards the First Galaxies

The formation of the first galaxies at redshifts z~10-15 signaled the transition from the simple initial state of the universe to one of ever increasing complexity. We here review recent progress in understanding their assembly process with numerical simulations, starting with cosmological initial conditions and modelling the detailed physics of star formation. In particular, we study the role of HD cooling in ionized primordial gas, the impact of UV radiation produced by the first stars, and the propagation of the supernova blast waves triggered at the end of their brief lives. We conclude by discussing promising observational diagnostics that will allow us to probe the properties of the first galaxies, such as their contribution to reionization and the chemical abundance pattern observed in extremely low-metallicity stars.

astro-ph↗
arXiv2009

Cosmological Systematics Beyond Nuisance Parameters : Form Filling Functions

In the absence of any compelling physical model, cosmological systematics are often misrepresented as statistical effects and the approach of marginalising over extra nuisance systematic parameters is used to gauge the effect of the systematic. In this article we argue that such an approach is risky at best since the key choice of function can have a large effect on the resultant cosmological errors. As an alternative we present a functional form filling technique in which an unknown, residual, systematic is treated as such. Since the underlying function is unknown we evaluate the effect of every functional form allowed by the information available (either a hard boundary or some data). Using a simple toy model we introduce the formalism of functional form filling. We show that parameter errors can be dramatically affected by the choice of function in the case of marginalising over a systematic, but that in contrast the functional form filling approach is independent of the choice of basis set. We then apply the technique to cosmic shear shape measurement systematics and show that a shear calibration bias of |m(z)|< 0.001(1+z)^0.7 is required for a future all-sky photometric survey to yield unbiased cosmological parameter constraints to percent accuracy. A module associated with the work in this paper is available through the open source iCosmo code available at http://www.icosmo.org .

astro-ph↗