Related papers: Two Windows on Acceleration and Gravitation: Dark …
Gravlenses are efficiently explored for detecting the most distant galaxies (up to z=10 redshifts). As an example of the role played by gravlenses we refer to the observation of the galaxy merger at z=3 (Borys, et al; Berciano Alba, et al).…
The cosmological redshifts z in the frequencies of spectral lines from distant galaxies as compared with their values observed in terrestrial laboratories, which are due to the scale factor a(t), frequently are interpret as a…
The light we observe from distant astrophysical objects including supernovae and quasars allows us to determine large distances in terms of a cosmological model. Despite the success of the standard cosmological model in fitting the data,…
One of the great endeavors of the past decade has been the evaluation of different observational techniques for measuring dark energy properties and of theoretical techniques for constraining models of cosmic acceleration given cosmological…
With the developments of large galaxy surveys or cosmic shear surveys it is now possible to map the dark matter distribution at truly cosmological scales. Detailed examinations of the statistical properties of the dark matter distribution…
We consider the impact of key astrophysical and measurement systematics on constraints on dark energy and modifications to gravity on cosmic scales. We focus on upcoming photometric "Stage III" and "Stage IV" large scale structure surveys…
The Lenses Structure and Dynamics (LSD) Survey aims at measuring the luminous and dark matter distribution of high redshift early-type galaxies by combining gravitational lens analysis with newly determined velocity dispersion profiles.…
The phenomenon of cosmic shear, or distortion of images of distant sources unaccompanied by magnification, is an effective way of probing the content and state of the foreground Universe, because light rays do not have to pass through mass…
Weak lensing can be observed through a number of effects on the images of distant galaxies; their shapes are sheared, their sizes and fluxes (magnitudes) are magnified and their positions on the sky are modified by the lensing field. Galaxy…
It has recently been shown that the observed Hubble function for cosmological expansion can be fitted accurately back to redshift unity (7.33 Gyr ago) with only one free constant, while neglecting cosmic curvature and mass, using the…
Flexion is the significant third-order weak gravitational lensing effect responsible for the weakly skewed and arc-like appearance of lensed galaxies. Here we demonstrate how flexion measurements can be used to measure galaxy halo density…
We show that gravitational lensing can provide a direct method to probe the nature of dark energy at astrophysical scales. For lensing system as an isolated astrophysical object, we derive the dark energy contribution to gravitational…
In the timescape scenario cosmic acceleration is understand as an apparent effect, due to gravitational energy gradients that grow when spatial curvature gradients become significant with the nonlinear growth of cosmic structure. This…
We outline how redshift-space distortions (RSD) can be measured from the angular correlation function w({\theta}), of galaxies selected from photometric surveys. The natural degeneracy between RSD and galaxy bias can be minimized by…
Rich and massive clusters of galaxies at intermediate redshift are capable of magnifying and distorting the images of background galaxies. A comparison of different mass estimators among these clusters can provide useful information about…
We use data from observational cosmology to put constraints on higher-dimensional extensions of general relativity in which the effective four-dimensional dark-energy density (or cosmological "constant") decays with time. In particular we…
The observed acceleration of the Universe can be explained by modifying general relativity. One such attempt is the nonlocal model of Deser and Woodard. Here we fix the background cosmology using results from the Planck satellite and…
Concepts like peculiar velocity, gravitational force, and power spectrum and their interrelationships are of utmost importance in the theories of structure formation. The observational implementation of these concepts is usually based on…
In this letter, we discuss a new method to probe the redshift evolution of the gas depletion factor, i.e. the ratio by which the gas mass fraction of galaxy clusters is depleted with respect to the universal mean of baryon fraction. The…
A moderate investment of observing time with the International X-ray Observatory to study high-redshift galaxy clusters detected in future large-scale surveys, will provide cosmological measurements of fundamental importance. IXO…