17,837 research outputs found
Coherent Combination of Baryon Acoustic Oscillation Statistics and Peculiar Velocity Measurements from Redshift Survey
New statistical method is proposed to coherently combine Baryon Acoustic
Oscillation statistics (BAO) and peculiar velocity measurements exploiting
decomposed density-density and velocity-velocity spectra in real space from the
observed redshift distortions in redshift space, 1) to achieve stronger dark
energy constraints, \sigma(w)=0.06 and \sigma(w_a)=0.20, which are enhanced
from BAO or velocity measurements alone, and 2) to cross-check consistency of
dark energy constraints from two different approaches; BAO as geometrical
measurements and peculiar velocity as large scale structure formation
observables. In addition to those advantages, as power spectra decomposition
procedure is free from uncertainty of galaxy bias, this simultaneous fitting is
an optimal method to extract cosmological parameters without any pre-assumption
about galaxy bias.Comment: 6 pages, 4 figures, PRD submitte
Large Scale Structure Formation of Normal Branch in DGP Brane World Model
In this paper, we study the large scale structure formation of the normal
branch in DGP model (Dvail, Gabadadze and Porrati brane world model) by
applying the scaling method developed by Sawicki, Song and Hu for solving the
coupled perturbed equations of motion of on-brane and off-brane. There is
detectable departure of perturbed gravitational potential from LCDM even at the
minimal deviation of the effective equation of state w_eff below -1. The
modified perturbed gravitational potential weakens the integrated Sachs-Wolfe
effect which is strengthened in the self-accelerating branch DGP model.
Additionally, we discuss the validity of the scaling solution in the de Sitter
limit at late times.Comment: 6 pages, 2 figure
A covariant Lagrangian for stable nonsingular bounce
The nonsingular bounce models usually suffer from the ghost or gradient
instabilities, as has been proved recently. In this paper, we propose a
covariant effective theory for stable nonsingular bounce, which has the
quadratic order of the second order derivative of the field but the
background set only by . With it, we explicitly construct a fully
stable nonsingular bounce model for the ekpyrotic scenario.Comment: 12 pages, 6 figures; published in JHEP; an Appendix and references
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