XIème Ecole de Cosmologie
17 - 22 septembre 2012 IESC, Cargèse
 Lentilles gravitationnelles
leur impact dans l’étude des galaxie et la cosmologie

Cosmography with strong lensing systems - joint analysis

Beata MALEC
Copernicus Center for Interdisciplinary Studies

Poster

Résumé : A key issue of contemporary cosmology is the problem of currently accelerating expansion of the Universe. The nature of this phenomenon is one of the most outstanding problems of physics and astronomy today. Its origin may be attributed to either unknown exotic material component with negative pressure - so called Dark Energy (DE), to infra red modification of gravity at cosmological scale or requires to relax the assumption of homogeneity of the Universe. It should be pointed out that the strength of modern cosmology (which now enterd stage dubbed the era of precision cosmology) lies in consistency across independent pieces of evidence rather than in single, crucial
experiment. We approach to this subject from phenomenological point of view. In this spirit we perform a cosmographic analysis using several cosmological probes such as Type Ia Supernovae (Union2 compilation), data from Cosmic Microwave Background (WMAP7), Baryon Acoustic Oscillation (BAO) and strongly gravitationally lensed systems (combined data sets from SLACS and LSD surveys) and Gamma Ray Bursts. These tests falls into two distinct cathegories. The first one makes use of the angular diameter distance, and refers to the so called standard rulers. Here we have strong lensing systems, shift parameter R from CMB and BAO scales. The second uses the luminosity distance and then we deal with standard (or rather standarizable) candles. Here we deal with SN Ia and GRB. The two distance concepts, although theoretically related to each other, in practice have different systematic uncertainties and different parameter degeneracies.Hence their joint analysis is more restrictive in the parameter space. We considered several cosmological scenarios of dark energy, widely discussed in current literature. We also address the question which model is the best with information-theoretic criteria: the Akaike Criterion (AIC) and Bayesian Information Criterion (BIC).
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Programme