Related papers: Cosmic Shear from Galaxy Spins
We search for evidence of primordial chirality violation in the galaxy data from the Sloan Digital Sky Survey by comparing how strongly directions of galaxy angular momenta correlate with left and right helical components of a spin vector…
As the volume and quality of modern galaxy surveys increase, so does the difficulty of measuring the cosmological signal imprinted in galaxy shapes. Weak gravitational lensing sourced by the most massive structures in the Universe generates…
Large scale correlations in the orientations of galaxies can result from alignments in their angular momentum vectors. These alignments arise from the tidal torques exerted on neighboring proto-galaxies by the smoothly varying shear field.…
The tidal gravitational field of galaxy clusters causes a coherent distortion of the images of background sources. Since the distribution of image distortions, namely the shear field, traces the local gravitational potential of a deflector,…
Cosmic shear leads to a correlation of the observed ellipticities of galaxies, an effect which is used to place constraints on cosmological parameters, and to explore the evolution of dark matter and dark energy in the universe. However, a…
I review the theory of angular momentum acquisition of galaxies by tidal torquing, the resulting angular momentum distribution, the angular momentum correlation function and discuss the implications of angular momentum alignments on weak…
Point estimators for the shearing of galaxy images induced by gravitational lensing involve a complex inverse problem in the presence of noise, pixelization, and model uncertainties. We present a probabilistic forward modeling approach to…
We investigate the problem of noise bias in maximum likelihood and maximum a posteriori estimators for cosmic shear. We derive the leading and next-to-leading order biases and compute them in the context of galaxy ellipticity measurements,…
Galaxy spins are believed to retain the initially acquired tendency of being aligned with the intermediate principal axes of the linear tidal field, which disseminates a prospect of using them as a probe of early universe physics. This…
Statistics of the weak lensing of galaxies can be used to constrain cosmology if the galaxy shear can be estimated accurately. In general this requires accurate modelling of unlensed galaxy shapes and the point spread function (PSF). I…
An explicit full nulling scheme for cosmic shear observations is presented. It makes possible the construction of shear maps from extended source distributions for which the lens distance distribution is restricted to a definite interval.…
We report a direct observational evidence for the existence of the galaxy spin alignments with the real space tidal field. We calculate the real space tidal field from the real space density field reconstructed recently from the Two Mass…
In this paper, we revisit the aquisition of angular momentum of galaxies by tidal shearing and compute the angular momentum variance sigma_L^2 as well as the angular momentum correlation function C_L(r) from a peak-restricted Gaussian…
Using data from the Sloan Digital Sky Survey we study correlations between directions of galaxy angular momenta determined from images of spiral galaxies and various observables derived from the reconstructed initial conditions. We find an…
Galaxy shapes are not randomly oriented, rather they are statistically aligned in a way that can depend on formation environment, history and galaxy type. Studying the alignment of galaxies can therefore deliver important information about…
Cosmic shear probes the distribution of dark matter via gravitational lensing of distant, background galaxies. We describe our cosmic shear survey consisting of deep blank fields observed with the Keck II telescope. We have found biases in…
We infer gravitational lensing shear and convergence fields from galaxy ellipticity catalogs under a spatial process prior for the lensing potential. We demonstrate the performance of our algorithm with simulated Gaussian-distributed…
The first detections of cosmic shear signal reported recently by 4 independent groups cover angular scales between one and 10 arcmin. On those scales, the cosmic shear is a signature of non-linear perturbations, like groups and clusters of…
We discuss the present status and future prospects for cosmic shear observations and their cosmological constraints. We review the evidences supporting the cosmological origin of the measured signal, and discuss the possible problems coming…
The angular momentum of galaxies is routinely ascribed to a process of tidal torques acting during the early stages of gravitational collapse, and is predicted from the initial mass distribution using second-order perturbation theory and…