13,122 research outputs found

    The dependence of cosmological parameters estimated from the microwave background on non-gaussianity

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    The estimation of cosmological parameters from cosmic microwave experiments has almost always been performed assuming gaussian data. In this paper the sensitivity of the parameter estimation to different assumptions on the probability distribution of the fluctuations is tested. Specifically, adopting the Edgeworth expansion, I show how the cosmological parameters depend on the skewness of the C_l spectrum. In the particular case of skewness independent of the multipole number I find that the primordial slope, the baryon density and the cosmological constant increase with the skewness.Comment: 4 pages, 4 figure

    A "double coincidence" search model of money

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    According to Engineer and Shi (1998, 2001) and Berentsen and Rocheteau (2003), the double coincidence of wants problem seems to be not essential to rationalize the use of money in a search theoretic framework. This paper analyzes an endogenous price search model of money where there is universal double coincidence of wants. The existence of a monetary equilibrium depends, essentially, on the asymmetry in the role played by economic agents in the exchange and production processes. In particular, entrepreneurs are assumed to produce a fixed amount of a divisible consumption good by means of labour services provided by workers. Entrepreneurs can offer a co-operative (barter) contract or a monetary contract to workers. Under the co-operative contract real wages are determined in the labour exchange sector, while in the monetary regime real wages are determined in the commodity exchange sector. The monetary contract is proved to be an equilibrium strategy provided that: (i) the workers' labour disutility is sufficiently high and/or (ii) the entrepreneurs' bargaining power in the commodity market is sufficiently large relative to their bargaining power in the labour market. The rationale for money comes from the fact that entrepreneurs use it as an instrument to maximize their output share.

    Non-Gaussian statistics of pencil beam surveys

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    We study the effect of the non-Gaussian clustering of galaxies on the statistics of pencil beam surveys. We find that the higher order moments of the galaxy distribution play an important role in the probability distribution for the power spectrum peaks. Taking into account the observed values for the kurtosis of galaxy distribution we derive the general probability distribution for the power spectrum modes in non-Gaussian models and show that the probability to obtain the 128\hm periodicity found in pencil beam surveys is raised by roughly one order of magnitude. The non-Gaussianity of the galaxy distribution is however still insufficient to explain the reported peak-to-noise ratio of the periodicity, so that extra power on large scales seems required.Comment: 9 pages,2 figs available on request,Latex, revised version with significant changes, preprint Fermilab-Pub-94-043-

    Orientable closed 3-manifolds with surface-complexity one

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    After a short summary of known results on surface-complexity of closed 3-manifolds, we will classify all closed orientable 3-manifolds with surface-complexity one.Comment: 9 pages, 3 figures, 1 table; minor changes: appendix on a theorem stated in arXiv:0804.0695 adde

    Chaplygin gas in light of recent Integrated Sachs--Wolfe effect data

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    We investigate the possibility of constraining Chaplygin dark energy models with current Integrated Sachs Wolfe effect data. In the case of a flat universe we found that generalized Chaplygin gas models must have an energy density such that Ωc>0.55\Omega_c >0.55 and an equation of state w<−0.6w <-0.6 at 95% c.l.. We also investigate the recently proposed Silent Chaplygin models, constraining Ωc>0.55\Omega_c >0.55 and w<−0.65w <-0.65 at 95% c.l.. Better measurements of the CMB-LSS correlation will be possible with the next generation of deep redshift surveys. This will provide independent and complementary constraints on unified dark energy models such as the Chaplygin gas.Comment: 5 pages, 4 figure
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