Jan M. Kratochvil

Testing the cosmological constant as a candidate for dark energy

It may be difficult to single out the best model of dark energy on the basis of the existing and planned cosmological observations, because many different models can lead to similar observational consequences. However, each particular model can be studied and either found consistent with observations or ruled out. In this paper, we concentrate on the possibility to test and rule out the simplest and by far the most popular of the models of dark energy, the theory described by general relativity with positive vacuum energy (the cosmological constant). We evaluate the conditions under which this model could be ruled out by the future observations made by the Supernova/Acceleration Probe SNAP (both for supernovae and weak lensing) and by the Planck Surveyor cosmic microwave background satellite.

Probing cosmology with weak lensing peak counts

We propose counting peaks in weak lensing (WL) maps, as a function of their height, to probe models of dark energy and to constrain cosmological parameters. Because peaks can be identified in two-dimensional WL maps directly, they can provide constraints that are free from potential selection effects and biases involved in identifying and determining the masses of galaxy clusters. As a pilot study, we have run cosmological N-body simulations to produce WL convergence maps in three models with different constant values of the dark energy equation-of-state parameter,

Current observational constraints on cosmic doomsday

w=\ensuremath{-}0.8

Cosmological information in weak lensing peaks

,

Preheating in new inflation

\ensuremath{-}1

EFFECT OF MEASUREMENT ERRORS ON PREDICTED COSMOLOGICAL CONSTRAINTS FROM SHEAR PEAK STATISTICS WITH LARGE SYNOPTIC SURVEY TELESCOPE

, and

Emulating the CFHTLenS weak lensing data: Cosmological constraints from moments and Minkowski functionals

\ensuremath{-}1.2

Impact of magnification and size bias on the weak lensing power spectrum and peak statistics

, with a fixed normalization of the primordial power spectrum (corresponding to present-day normalizations of

Masked areas in shear peak statistics. A forward modeling approach

{\ensuremath{\sigma}}_{8}=0.742

Observational bounds on cosmic doomsday

, 0.798, and 0.839, respectively). By comparing the number of WL peaks in eight convergence bins in the range of