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The meaning of "linear expansion" is explained. Particularly accurate relative distances are compiled and homogenized a) for 246 SNe Ia and 35 clusters with v<30,000 km/s, and b) for relatively nearby galaxies with 176 TRGB and 30 Cepheid…

宇宙学与河外天体物理 · 物理学 2015-03-13 A. Sandage , B. Reindl , G. A. Tammann

Our motion through the Universe generates a dipole in the temperature anisotropies of the Cosmic Microwave Background (CMB) and also in the angular distribution of sources. If the cosmological principle is valid, these two dipoles are…

宇宙学与河外天体物理 · 物理学 2023-06-09 Charles Dalang , Camille Bonvin

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…

宇宙学与河外天体物理 · 物理学 2023-05-19 Oliver T. Oayda , Geraint F. Lewis

The acceleration of the cosmic expansion has been discovered as a consequence of redshift Supernovae data. In the usual way, this cosmic acceleration is explained by the presence of a positive cosmological constant or quantum vacuum energy,…

广义相对论与量子宇宙学 · 物理学 2007-05-23 J. -F. Pascual-Sánchez

We investigate dipole asymmetries in four large radio surveys, each spanning more than 80\% of the sky. Two of them, the Very Large Array Sky Survey (VLASS) and the Rapid ASKAP Continuum Survey (RACS), have recently yielded dipoles that…

宇宙学与河外天体物理 · 物理学 2024-10-10 Ashok K. Singal

We investigate the effects of the presence of relic classical superhorizon inhomogeneities during inflation. This superhorizon inhomogeneity appears as a gradient locally and picks out a preferred direction. Quantum fluctuations on this…

宇宙学与河外天体物理 · 物理学 2011-07-25 Xian Gao

We explore a model of the early universe in which the inflationary epoch is preceded by a cosmic bounce, and argue that this scenario provides a common origin to several of the anomalous features that have been observed at large angular…

宇宙学与河外天体物理 · 物理学 2021-02-17 Ivan Agullo , Dimitrios Kranas , V. Sreenath

The presence of a dipolar statistical anisotropy in the spectrum of cosmic microwave background (CMB) fluctuations was reported by the Wilkinson Microwave Anisotropy Probe (WMAP), and has recently been confirmed in the Planck 2013 analysis…

宇宙学与河外天体物理 · 物理学 2014-04-29 Sugumi Kanno , Misao Sasaki , Takahiro Tanaka

Cross-correlation between the CMB and large-scale structure is a powerful probe of dark-energy and gravity on the largest physical scales. We introduce a novel estimator, the CMB-velocity correlation, that has most of his power on large…

天体物理学 · 物理学 2008-11-26 Pablo Fosalba , Olivier Doré

A large bulk flow, which is in tension with the Lambda Cold Dark Matter ($\Lambda$CDM) cosmological model, has been observed. In this paper, we provide a physically plausible explanation of this bulk flow, based on the assumption that some…

宇宙学与河外天体物理 · 物理学 2011-05-19 Yin-Zhe Ma , Christopher Gordon , Hume A. Feldman

We propose that several of the anomalies that have been observed at large angular scales in the CMB have a common origin in a cosmic bounce that took place before the inflationary era. The bounce introduces a new physical scale in the…

宇宙学与河外天体物理 · 物理学 2022-07-27 Ivan Agullo , Dimitrios Kranas , V. Sreenath

Standard inflationary hot big bang cosmology predicts small fluctuations in the Cosmic Microwave Background (CMB) with isotropic Gaussian statistics. All measurements support the standard theory, except for a few anomalies discovered in the…

We determine the dipole in the WISE galaxy catalogue. After reducing star contamination to <0.1% by rejecting sources with high apparent motion and those close to the Galactic plane, we eliminate low redshift sources to suppress the…

宇宙学与河外天体物理 · 物理学 2018-04-30 M. Rameez , R. Mohayaee , S. Sarkar , J. Colin

We use linear estimators to determine the magnitude and direction of the cosmic radio dipole from the NRAO VLA Sky Survey (NVSS) and the Westerbork Northern Sky Survey (WENSS). We show that special attention has to be given to the issues of…

宇宙学与河外天体物理 · 物理学 2013-07-25 Matthias Rubart , Dominik J. Schwarz

We show that perturbations generated during the anisotropic pre-inflationary stage of cosmic evolution may affect cosmological observations today for a certain range of parameters. Due to the anisotropic nature of the universe during such…

宇宙学与河外天体物理 · 物理学 2017-09-15 Pavan K. Aluri , Pankaj Jain

We extend the curvaton scenario presented by Erickcek et al. (2008, 2009), to explain how the even-odd multipole asymmetry of the Cosmic Microwave Background (CMB) (also called parity asymmetry, (Kim & Naselsky 2010)) and power anisotropies…

宇宙学与河外天体物理 · 物理学 2013-08-29 Hao Liu , Anne Mette Frejsel , Pavel Naselsky

In the concordance model of the Universe, the matter distribution - as observed in galaxy number counts or the intensity of line emission (such as the 21cm line of neutral hydrogen) - should have a kinematic dipole due to the Sun's motion…

宇宙学与河外天体物理 · 物理学 2018-01-19 Roy Maartens , Chris Clarkson , Song Chen

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

In this work, I present a generalized linear Hubble law for a barotropic spherically symmetric inhomogeneous spacetime, which is in principle compatible with the acceleration of the cosmic expansion obtained as a result of high redshift…

广义相对论与量子宇宙学 · 物理学 2014-11-17 J. -F. Pascual-Sánchez

The measurements of CMB anisotropy have opened up a window for probing the global topology of the universe on length scales comparable to and beyond the Hubble radius. For compact topologies, the two main effects on the CMB are: (1) the…

天体物理学 · 物理学 2011-04-15 J. Richard Bond , Dmitri Pogosyan , Tarun Souradeep