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We studied the distribution of star-forming galaxies in the classical Millenium Simulation Springer et al. [1] and the Horizon Runs Kim et al. [2] databases. DeLucia and Blaizot [3] used a semi-analytical model for the galaxy genesis in Millenium I. We found a relationship between the distribution of the star-forming galaxies and the dark matter (DM), which we used as a transformation factor from the Millenium I to Millenium XXL. We simulated a star-forming galaxy sample with Markov Chain Monte Carlo (MCMC) method, and checked the relation between structures and the distribution of star-forming groups on a various scales. We concluded that above the BAO-scale we need a much more numerous sample than that of the current 407 GRBs to reveal the DM distribution. We got similar results applying our method to the Horizon Runs data. [ABSTRACT FROM AUTHOR]

Gamma ray burst light curves have been analyzed using a special wavelet transformation. The applied wavelet base is based on a typical Fast Rise-Exponential Decay (FRED) pulse. The shape of the wavelet coefficients’ total distribution is determined on the observational frequency grid. Our analysis indicates that the pulses in the long bursts’ high energy channel lightcurves are more FRED-like than the lower ones, independently from the actual physical time-scale. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

It is -known that the soft tail of gamma-ray bursts' spectra show excesses from the exact power-law dependence. In this article we show that this departure can be detected in the peak flux ratios of different BATSE DISCSC energy channels. This effect allows us to estimate the redshifts of bright long gamma-ray bursts given in the BATSE Catalog. For the 8 gamma-ray bursts, which have both BATSE DISCSC data and measured optical spectroscopic redshifts, the correlation between the true and estimated redshifts is remarkable, and the average error is Δz ≈ 0.5. The method is similar to the photometric redshift estimation of galaxies in the optical range, hence we call it "gamma photometric redshift estimation". These redshifts for the remaining 857 long bright gamma-ray bursts are are up to z ... (4 - 7). For the the faint long bursts — which should be up to z ... 20 — the redshifts hardly can be determined unambiguously from this method. [ABSTRACT FROM AUTHOR]

Swift satellite measurements contributed substantially to the gamma-ray burst (GRB) redshift observations through fast slewing to the source of the GRBs. Still, a large number of bursts are without redshift. We study the celestial distribution of bursts with various methods and compare them to a random catalog using Monte-Carlo simulations. We find an anisotropy in the distribution of the intermediate class of bursts and find that the short and long population are distributed isotropically. [ABSTRACT FROM AUTHOR]