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The velocity anisotropy parameter, beta, is a measure of the kinematic state of orbits in the stellar halo which holds promise for constraining the merger history of the Milky Way (MW). We determine global trends for beta as a function of…

By comparing with the most recent experimental results, we point out the model dependence of the present bounds on the anisotropy of the speed of light. In fact, by replacing the CMB with a class of preferred frames that can better account…

广义相对论与量子宇宙学 · 物理学 2007-05-23 C. M. L. de Aragao , M. Consoli , A. Grillo

We derive upper and lower limits for the basic physical parameters (mass-radius ratio, anisotropy, redshift and total energy) for arbitrary anisotropic general relativistic matter distributions in the presence of a cosmological constant.…

广义相对论与量子宇宙学 · 物理学 2007-05-23 C. G. Boehmer , T. Harko

We present a novel approach to disentangle two key contributions to the largest-scale anisotropy of the galaxy distribution: (i) the intrinsic dipole due to clustering and anisotropic geometry, and (ii) the kinematic dipole due to our…

宇宙学与河外天体物理 · 物理学 2021-11-09 Tobias Nadolny , Ruth Durrer , Martin Kunz , Hamsa Padmanabhan

Recently, an anisotropic cosmological model was proposed. An arbitrary 1-form, which picks out a privileged axis in the universe, was added to the Friedmann-Robertson-Walker line element. The distance-redshift relation was modified such…

宇宙学与河外天体物理 · 物理学 2014-05-14 Zhe Chang , Xin Li , Hai-Nan Lin , Sai Wang

A recent study of the rotation of the plane of polarization of light from 160 cosmological sources claims to find significant evidence for cosmological anisotropy. We point out methodological weaknesses of that study, and reanalyze the same…

天体物理学 · 物理学 2009-12-30 Thomas J. Loredo , Eanna E. Flanagan , Ira M. Wasserman

The CMB data recently released by BOOMERANG and MAXIMA suggest that the anisotropy spectrum has a third peak in the range 800<l_3<900. A combination of this result with constraints from large-scale structure permit us to differentiate…

天体物理学 · 物理学 2009-11-06 Michael Doran , Matthew Lilley , Christof Wetterich

We present new analytical distribution functions for anisotropic spherical galaxies. They have the density profiles of the gamma-models, which allow a wide range of central density slopes, and are widely used to fit elliptical galaxies and…

天体物理学 · 物理学 2008-11-26 Pieter Buyle , Chris Hunter , Herwig Dejonghe

In general relativity gravitational waves propagate at the speed of light, however in alternative theories of gravity that might not be the case. We study the effects of a modified speed of gravity, $c_T^2$, on the B-modes of the Cosmic…

宇宙学与河外天体物理 · 物理学 2015-03-11 Marco Raveri , Carlo Baccigalupi , Alessandra Silvestri , Shuang-Yong Zhou

We provide the first direct lifting of the mass/anisotropy degeneracy for a cluster of galaxies, by jointly fitting the line of sight velocity dispersion and kurtosis profiles of the Coma cluster, assuming an NFW tracer density profile, a…

天体物理学 · 物理学 2007-05-23 Gary A. Mamon , Ewa L. Lokas , Teresa Sanchis

This paper derives central limit and bootstrap theorems for probabilities that sums of centered high-dimensional random vectors hit hyperrectangles and sparsely convex sets. Specifically, we derive Gaussian and bootstrap approximations for…

统计理论 · 数学 2016-03-09 Victor Chernozhukov , Denis Chetverikov , Kengo Kato

We consider structure formation and CMB anisotropies in a closed universe, both with and without a cosmological constant. The CMB angular power spectrum and the matter transfer function are presented, along with a discussion of their…

天体物理学 · 物理学 2009-08-18 Martin White , Douglas Scott

We test claims of large-scale anisotropy in the local expansion rate using cluster scaling relations as distance indicators. Using a Bayesian forward model, we jointly fit the X-ray luminosity--temperature (LT) and thermal…

宇宙学与河外天体物理 · 物理学 2026-02-06 Tariq Yasin , Richard Stiskalek , Harry Desmond , Sebastian von Hausegger , Pedro G. Ferreira

In this manuscript, we investigate the patterns satisfied by the cosmological anisotropy under the hypothesis of the observers being co-moving with a perfect fluid whose induced space sections are homogeneous with vanishing scalar…

广义相对论与量子宇宙学 · 物理学 2021-03-31 Leandro G. Gomes

If the augmented density of a spherical anisotropic system is assumed to be multiplicatively separable to functions of the potential and the radius, the radial function, which can be completely specified by the behavior of the anisotropy…

宇宙学与河外天体物理 · 物理学 2011-07-21 J. An

The nature of dark matter is increasingly constrained by cosmological data. In this paper, we examine the implications of the Cosmic Microwave Background anisotropy limits on the density of cold dark matter under different theoretical…

天体物理学 · 物理学 2009-11-07 A. Melchiorri , J. Silk

We present density profiles, that are solutions of the spherical Jeans equation, derived under the following two assumptions: (i) the coarse grained phase-density follows a power-law of radius, rho/(sigma^3) proportional to r^{-alpha}, and…

天体物理学 · 物理学 2009-11-07 Nicolaos Hiotelis

Spatially referenced data often have autocovariance functions with elliptical isolevel contours, a property known as geometric anisotropy. The anisotropy parameters include the tilt of the ellipse (orientation angle) with respect to a…

统计理论 · 数学 2021-10-04 Manolis P. Petrakis , Dionissios T. Hristopulos

The large-scale structure in the distribution of galaxies is thought to arise from the gravitational instability of small fluctuations in the initial density field of the universe. A key test of this hypothesis is that superclusters of…

The Cosmological Principle states that the universe is statistically isotropic and homogeneous on large length scales, typically $\gtrsim 70$Mpc. A detection of significant deviation would help us falsify the simplest models of inflation.…

宇宙学与河外天体物理 · 物理学 2025-08-26 Bhuwan Joshi , Rahul Kothari