7 research outputs found
Problems of Clustering of Radiogalaxies
We present the preliminary analysis of clustering of a sample of 1157
radio-identified galaxies from Machalski & Condon (1999). We found that for
separations Mpc their redshift space autocorrelation function
can be approximated by the power law with the correlation length Mpc and slope . The correlation length for
radiogalaxies is found to be lower and the slope steeper than the corresponding
parameters of the control sample of optically observed galaxies. Analysis the
projected correlation function displays possible differences in the
clustering properties between active galactic nuclei (AGN) and starburst (SB)
galaxies.Comment: Submitted: Proceedings of IAUS 290 "Feeding Compact Objects:
Accretion on All Scales", C. M. Zhang, T. Belloni, M. Mendez & S. N. Zhang
(eds.
Can the initial singularity be detected by cosmological tests?
In the present paper we raise the question whether initial cosmological
singularity can be proved from the cosmological tests. The classical general
relativity predict the existence of singularity in the past if only some energy
conditions are satisfied. On the other hand the latest quantum gravity
applications to cosmology suggest of possibility of avoiding the singularity
and replace it with the bounce. The distant type Ia supernovae data are used to
constraints on bouncing evolutional scenario where square of the Hubble
function is given by formulae
, where are density parameters and . We show that the on the
base of the SNIa data standard bouncing models can be ruled out on the
confidence level. If we add the cosmological constant to the standard
bouncing model then we obtain as the best-fit that the parameter
is equal zero which means that the SNIa data do not support the bouncing term
in the model. The bounce term is statistically insignificant the present epoch.
We also demonstrate that BBN offer the possibility of obtaining stringent
constraints of the extra term . The other observational test
methods like CMB and the age of oldest objects in the Universe are used. We
also use the Akaike informative criterion to select a model according to the
goodness of fit and we conclude that this term should be ruled out by Occam's
razor, which makes that the big bang is favored rather then bouncing scenario.Comment: 30 pages, 7 figures improved versio
Philosophical Choice between Indifference Principle and Fine-Tuning Principle
We formulate a cosmogonic indifference principle in cosmology in terms of a dynamical system theory. While the choice between generic and fine tuned initial condition for our Universe has a rather philosophical character, there is a very generic set of initial conditions which give rise to the concordance inflectional ΛCDM model which becomes in good agreement with astronomical observations
The Problems Of Classical Cosmology Motivation For The Quantum Gravity Theory
In this paper it is investigated the standard problems of relativistic cosmology like: singularity problem, flatness problem, horizon problem, acceleration problem and problem of structure origin. We discuss nature of these difficulties and we suggest existence of some analogies to the problems of Newtonian cosmology. We argue that the existence of serious problems of relativistic cosmology is strictly related with our understanding of space-time. The overcome of these problems means the exit beyond the standard model. We pointed out that the loop quantum gravity seems to be correct step toward to overcome problems of relativistic cosmology
SOME OF TOPOLOGICAL AND METHODOLOGICAL ASPECTS OF QUANTUM COSMOLOGY MODELS
In this paper we address some critical remarks to two leading models quantum cosmology – Hawking-Hartle model and Vilenkin model. Both models appeal to different mathematical frame- works to reconstract of first moments of Universe ewolution. The first one presents wave function of the Universe using Feynman’s formalism of quantum mechanics — path integrals. The other one shows the beginnig of the Universe as quantum tunneling process. The authors of above mentioned approaches to quantum cosmology claims, that these mechanisms describe creation of the Universe ex nihilo. The main aim of tis paper is to show a weakness of such interpretations. Firstly, Gordon McCabe’s criticism is presented. His analyses are based on topological concept of cobordism. In the second step, we show that the concept of ex nihilo should be rather understood as “zero-point- geometry” with a material field.Artykuł prezentuje uwagi krytyczne pod adresem dwóch wiodących modeli kosmogenezy kwantowej – modelu Hawkinga – Hartle’a oraz modelu Vilenkina. Obydwa modele wykorzystują różne formalizmy w rekonstrukcji początkowych etapów ewolucji Wszechświata. Pierwszy konstruuje funkcję falową Wszechświata za pomocą feynmanowskiego całkowania po trajektoriach, natomiast drugi ukazuje pierwotną dynamikę Wszechświata jako efekt tunelowy. Twórcy obydwu koncepcji kosmologii kwantowej uważają, że prezentowane przez nich mechanizmy opisują kreację Wszechświata ex nihilo. Celem artykułu jest wskazanie na nieprawomocność takich wniosków. Najpierw zaprezentowana jest krytyka autorstwa Gordona McCabe’a, który swoje analizy opiera na topologicznym pojęciu kobordyzmu. Następnie wskazujemy na to, że stosowane w obu projektach pojęcie ex nihilo lepiej oddaje punkt geometryczny z zadanym polem materialnym