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

Measuring neutrino mass imprinted on the anisotropic galaxy clustering

The anisotropic galaxy clustering of large scale structure observed by the Baryon Oscillation Spectroscopic Survey Data Release 11 is analyzed to probe the sum of neutrino mass in the small $m_\nu < 1eV$ limit in which the early broadband shape determined before the last scattering surface is immune from the variation of $m_\nu$. The signature of $m_\nu$ is imprinted on the altered shape of the power spectrum at later epoch, which provides an opportunity to access the non--trivial $m_\nu$ through the measured anisotropic correlation function in redshift space (hereafter RSD instead of Redshift Space Distortion). The non--linear RSD corrections with massive neutrinos in the quasi linear regime are approximately estimated using one-loop order terms computed by tomographic linear solutions. We suggest a new approach to probe $m_\nu$ simultaneously with all other distance measures and coherent growth functions, exploiting this deformation of the early broadband shape of the spectrum at later epoch. If the origin of cosmic acceleration is unknown, $m_\nu$ is poorly determined after marginalising over all other observables. However, we find that the measured distances and coherent growth functions are minimally affected by the presence of mild neutrino mass. Although the standard model of cosmic acceleration is assumed to be the cosmological constant, the constraint on $m_\nu$ is little improved. Interestingly, the measured CMB distance to the last scattering surface sharply slices the degeneracy between the matter content and $m_\nu$, and the hidden $m_\nu$ is excavated to be $m_\nu=0.19^{+0.28}_{-0.17} eV$ which is different from massless neutrino more than 68% confidence.Comment: 11 pages, 4 figures, 2 table

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

Study on the mapping of dark matter clustering from real space to redshift space

The mapping of dark matter clustering from real space to redshift space introduces the anisotropic property to the measured density power spectrum in redshift space, known as the redshift space distortion effect. The mapping formula is intrinsically non-linear, which is complicated by the higher order polynomials due to indefinite cross correlations between the density and velocity fields, and the Finger-of-God effect due to the randomness of the peculiar velocity field. Whilst the full higher order polynomials remain unknown, the other systematics can be controlled consistently within the same order truncation in the expansion of the mapping formula, as shown in this paper. The systematic due to the unknown non-linear density and velocity fields is removed by separately measuring all terms in the expansion directly using simulations. The uncertainty caused by the velocity randomness is controlled by splitting the FoG term into two pieces, 1) the "one-point" FoG term being independent of the separation vector between two different points, and 2) the "correlated" FoG term appearing as an indefinite polynomials which is expanded in the same order as all other perturbative polynomials. Using 100 realizations of simulations, we find that the Gaussian FoG function with only one scale-independent free parameter works quite well, and that our new mapping formulation accurately reproduces the observed 2-dimensional density power spectrum in redshift space at the smallest scales by far, up to $k\sim 0.2h$Mpc, considering the resolution of future experiments.Comment: 17 pages, 14 figures. Accepted by JCAP. The computation of T term is corrected after JCAP revision, and new T term is tested in detail in Appendi

The Large Scale Structure of f(R) Gravity

We study the evolution of linear cosmological perturbations in f(R) models of accelerated expansion in the physical frame where the gravitational dynamics are fourth order and the matter is minimally coupled. These models predict a rich and testable set of linear phenomena. For each expansion history, fixed empirically by cosmological distance measures, there exists two branches of f(R) solutions that are parameterized by B propto d^2 f/dR^2. For B<0, which include most of the models previously considered, there is a short-timescale instability at high curvature that spoils agreement with high redshift cosmological observables. For the stable B>0 branch, f(R) models can reduce the large-angle CMB anisotropy, alter the shape of the linear matter power spectrum, and qualitatively change the correlations between the CMB and galaxy surveys. All of these phenomena are accessible with current and future data and provide stringent tests of general relativity on cosmological scales.Comment: 10 pages, 6 figures, minor typo fixes reflects version accepted by PR

Chasing Unbiased Spectra of the Universe

The cosmological power spectrum of the coherent matter flow is measured exploiting an improved prescription for the apparent anisotropic clustering pattern in redshift space. New statistical analysis is presented to provide an optimal observational platform to link the improved redshift distortion theoretical model to future real datasets. The statistical power as well as robustness of our method are tested against 60 realizations of 8 Gpc/h^3 dark matter simulation maps mocking the precision level of upcoming wide--deep surveys. We showed that we can accurately extract the velocity power spectrum up to quasi linear scales of k~0.1 h/Mpc at z = 0.35 and up to k~0.15 h/Mpc at higher redshifts within a couple of percentage precision level. Our understanding of redshift space distortion is proved to be appropriate for precision cosmology, and our statistical method will guide us to righteous path to meet the real world.Comment: 9 pages, 7 figure