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Under the assumption that they are standard(isable) candles, the lightcurves of Type Ia supernovae have been analyzed in the framework of the standard Friedmann-Lema\^itre-Robertson-Walker cosmology to conclude that the expansion rate of…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-14 Mohamed Rameez

The cosmological principle asserts that the Universe is homogeneous and isotropic on large enough scales. However, alternative cosmological models can bring about anisotropies through local inhomogeneities, anisotropic evolution, or exotic…

We test the isotropy of the Hubble diagram. At small redshifts, this is possible without assumptions on the cosmic inventory and provides a fundamental test of the cosmological principle. At higher redshift we check for the self-consistency…

Astrophysics · Physics 2011-07-28 Dominik J. Schwarz , Bastian Weinhorst

We critically assess the impact of significant dipole and large-scale anisotropies on galaxy clustering signals, with a focus on radio continuum surveys. Our study reveals that these anisotropies -- resulting from intrinsic cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-15 Prabhakar Tiwari

The Universe's assumed homogeneity and isotropy is known as the cosmological principle. It is one of the assumptions that lead to the Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) metric and it is a cornerstone of modern cosmology,…

Context. Our Local Group of galaxies appears to be moving relative to the cosmic microwave background with the source of the peculiar motion still uncertain. While in the past this has been studied mostly using galaxies as distance…

Galaxy clusters have their unique advantages for cosmology. Here we collect a new sample of 10 lensing galaxy clusters with X-ray observations to constrain cosmological parameters.The redshifts of lensing clusters lie between 0.1 and 0.6,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Heng Yu , Zong-Hong Zhu

Observations of distant supernovae indicate that the Universe is now in a phase of accelerated expansion the physical cause of which is a mystery. Formally, this requires the inclusion of a term acting as a negative pressure in the…

We propose and implement a novel, robust, and non-parametric test of statistical isotropy of the expansion of the universe, and apply it to around one thousand type Ia supernovae from the Pantheon sample. We calculate the angular clustering…

Cosmology and Nongalactic Astrophysics · Physics 2019-05-24 John Soltis , Arya Farahi , Dragan Huterer , C. Michael Liberato

There currently exist many observations which are not consistent with the cosmological principle. We review these observations with a particular emphasis on those relevant for Square Kilometre Array (SKA). In particular, several different…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-03 Shamik Ghosh , Pankaj Jain , Gopal Kashyap , Rahul Kothari , Sharvari Nadkarni-Ghosh , Prabhakar Tiwari

Recent released Planck data and other astronomical observations show that the universe may be anisotropic on large scales. This hints a cosmological privileged axis in our anisotropic expanding universe. This paper proceeds a modified…

General Relativity and Quantum Cosmology · Physics 2017-11-29 Amin Salehi , Mohammad Reza Setare

Recent observations suggest that there are violations of the isotropy of the universe at large scales, an important part of the cosmological principle. In this paper, we use the Cosmic Microwave Background (CMB) data to search for spatial…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-20 Shek Yeung , Ming-Chung Chu

We present a novel test of the cosmological principle: the idea that, on sufficiently large scales, the universe should appear homogeneous and isotropic to observers comoving with the Hubble flow. This is a fundamental assumption in modern…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-19 Oliver T. Oayda , Geraint F. Lewis

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…

Astrophysics · Physics 2007-05-23 Gary A. Mamon , Ewa L. Lokas , Teresa Sanchis

We probe the statistical isotropy hypothesis of the large-scale structure with the second Planck Sunyaev-Zeldovich (PSZ2) galaxy clusters data set. Our analysis adopts a statistical-geometrical method which compares the 2-point angular…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-15 C. A. P. Bengaly , A. Bernui , I. S. Ferreira , J. S. Alcaniz

This is the third of a series of papers in which we derive simultaneous constraints on cosmological parameters and X-ray scaling relations using observations of the growth of massive, X-ray flux-selected galaxy clusters. Our data set…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 David Rapetti , Steven W. Allen , Adam Mantz , Harald Ebeling

A key test of the isotropy of the Universe on large scales consists in comparing the dipole in the Cosmic Microwave Background (CMB) temperature with the dipole in the distribution of sources at low redshift. Current analyses find a dipole…

Cosmology and Nongalactic Astrophysics · Physics 2024-08-27 N. Grimm , M. Pijnenburg , S. Mastrogiovanni , C. Bonvin , S. Foffa , G. Cusin

Analyses of recent cosmic microwave background (CMB) observations have provided increasing indications for the existence of large scale anisotropy in the universe. Given the far reaching consequences of such an anisotropy for our…

Astrophysics · Physics 2009-09-29 A. Bernui , B. Mota , M. J. Reboucas , R. Tavakol

The breakdown of statistical homogeneity and isotropy of cosmic perturbations is a generic feature of ultra large scale structure of the cosmos, in particular, of non trivial cosmic topology. The statistical isotropy (SI) of the Cosmic…

Astrophysics · Physics 2007-05-23 Amir Hajian , Tarun Souradeep

We investigate the impact of different observational effects affecting a precise and accurate measurement of the growth rate of fluctuations from the anisotropy of clustering in galaxy redshift surveys. We focus on redshift measurement…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-23 Federico Marulli , Davide Bianchi , Enzo Branchini , Luigi Guzzo , Lauro Moscardini , Raul E. Angulo
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