07 - Large scale structures
- Vincent Desjacques ()
07 - Large scale structures
- Vincent Desjacques ()
David Wands (University of Portsmouth)
12/14/15, 2:00 PM
As high-redshift galaxy surveys probe ever larger volumes with increasing accuracy there is renewed interest, and some concern, about how the standard results derived within the standard Newtonian approach to large-scale structure should be understood within a relativistic framework. How and when do Newtonian results need to modified? Relativistic corrections arise in several ways. For...
Jaiyul Yoo (University of Zurich)
12/14/15, 2:21 PM
We present the third-order analytic solution of the matter density fluctuation in the proper-time hypersurface of nonrelativistic matter flows by solving the nonlinear general relativistic equations. The proper-time hypersurface provides a coordinate system that a local observer can set up without knowledge beyond its neighborhood, along with physical connections to the local Newtonian...
Enea Di Dio (OATs-INAF)
12/14/15, 2:42 PM
I will discuss the galaxy clustering in a relativistic framework in terms of observable quantities, i.e angles and redshifts. A relativistic description includes terms beyond the Kaiser approximation (doppler effects and galaxy evolution), gravitational potentials and integrated terms (cosmic magnification, integrated Sachs-Wolfe and Shapiro time-delay). These terms are currently neglected,...
275. Probing violations of slow-roll inflation at the largest observable scales with future galaxy surveys
Mario Ballardini (University of Bologna)
12/14/15, 3:03 PM
The predictions of the simplest inflationary models, such as a flat Universe and Gaussian adiabatic perturbations with a red tilt, provide a remarkable good fit to the most recent measurements of CMB temperature and polarization anisotropies. Nevertheless, deviations from a simple power-law spectrum provide a better fit to Planck temperature anisotropies data, in particular on the...
Francesco Montanari (Universite de Geneve (CH))
12/14/15, 3:24 PM
We investigate how well the lensing potential can be measured tomographically with future galaxy surveys using their number counts. Such a measurement is a consistency test of the standard ΛCDM framework. Based on galaxy angular-redshift power spectra, our analysis suggests that the survey can measure the amplitude of the lensing potential at the same level of precision as other standard ΛCDM...
Prof. Jai-chan Hwang (Kyunpook National Univ.)
12/14/15, 4:15 PM
We present the leading order nonlinear density and velocity power spectra including the vector- and tensor-type perturbation simultaneously excited by the scalar-type perturbation in nonlinear order. Concerning density and velocity perturbations of the pressureless matter in perturbation regime well inside of matter-dominated epoch, we show that pure Einstein’s gravity contributions...
Julian Adamek (Université de Genève)
12/14/15, 4:35 PM
The Newtonian approximation which is usually invoked in N-body simulations of cosmic large scale structure relies on the assumptions that gravitational fields are weak and that they are only sourced by nonrelativistic matter. The latter constitutes an implicit assumption about the nature of the "dark" components of the Universe (dark matter and dark energy), thereby precluding a serious...
248. Large Scale Structure with interacting Vacuum: the non-linear regime in the post-Friedman approximation
Marco Bruni (University of Portsmouth)
12/14/15, 4:55 PM
General-relativistic cosmological models where vacuum interacts with cold dark matter (iV-CDM models) maybe a good alternative to the standard LCDM scenario. The post-Friedmann approximation generalises to cosmology post-Newtonian methods and we have used it to extract frame-dragging, a pure GR effect, from standard N-body simulations in LCDM and in f(R) models. After briefly summarising the...
Vitalii Sliusar (Astronomical Observatory of Taras Shevchenko National University of Kyiv, Ukraine)
12/14/15, 5:15 PM
We propose a numerical approach to study the inhomogeneity growth in the Universe filled with a pressureless matter. The hydrodynamical equations for perturbations of the isotropic uniform cosmological background (non-relativistic stage) in the comoving frame are treated taking into account all nonlinear terms. The periodic boundary conditions are imposed. The problem is reduced to ordinary...
Sergey Sibiryakov (CERN & EPFL & INR RAS)
12/14/15, 5:35 PM
I will present a new perturbative approach to the description of cosmological structures in the mildly non-linear regime relevant at the distance scales from 10 to 100 Mpc. In this framework equal-time correlation functions of cosmological perturbations are calculated using an ensemble with time-dependent statistical weight. The scheme is free from unphysical infrared divergencies plaguing the...
Titouan Lazeyras (MPA)
12/14/15, 5:55 PM
The large-scale local bias parameters of dark matter halos are essential to describe the statistics of halos and galaxies on large scales, as well as for the halo model of the matter distribution. We recently obtained precise measurements of the three leading bias parameters from simulations using a novel technique : the separate universe simulations. For b_2 and b_3, these are the most...
Mr Junsup Shim (Seoul National University)
12/14/15, 6:15 PM
We present how an anisotropic pattern of the cosmic web, which is vividly reflected in the filamentary structure of supercluster, changes if 1)the nature of dark energy differs from the cosmological constant or 2)the gravitational law deviates from the general theory of relativity with/without massive neutrinos. 1)The coupled dark energy (cDE) model where the coupling between dark energy and...