English
Related papers

Related papers: Dipole Anisotropy from an Entropy Gradient

200 papers

Recent measurements of the dipole anisotropy in the arrival directions of Galactic cosmic rays (CRs) indicate a strong energy dependence of the dipole amplitude and phase in the TeV-PeV range. We argue here that these observations can be…

High Energy Astrophysical Phenomena · Physics 2016-10-13 Markus Ahlers

Kinematic dipole signal originates from the motion of the Sun with respect to the CMB rest frame. It is a remarkable signal, two orders of magnitude larger than the observed pattern of CMB anisotropies. Therefore the dipole subtraction from…

Astrophysics · Physics 2007-05-23 Alessandro Gruppuso , Carlo Burigana , Fabio Finelli

Recent claims in the literature have suggested that the {\it WMAP} quadrupole is not primordial in origin, and arises from an aliasing of the much larger dipole field because of incorrect satellite pointing. We attempt to reproduce this…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Adam Moss , Douglas Scott , Kris Sigurdson

Contaldi et al. [1] have suggested that an initial period of kinetic energy domination in single field inflation may explain the lack of CMB power at large angular scales. We note that in this situation it is natural that there also be a…

Astrophysics · Physics 2009-08-13 John F. Donoghue , Koushik Dutta , Andreas Ross

The velocity of the Sun with respect to the cosmic microwave background (CMB) can be extracted from the CMB dipole, provided its intrinsic dipole is assumed to be small in comparison. This interpretation is consistent, within fairly large…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-24 Charles Dalang , Ruth Durrer , Fabien Lacasa

I show that a cumulative contraction or expansion must result from repetitive tidal action in a curved stress field, depending on the direction of the curvature. The resulting expansion of solid materials onboard deep space probes and the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 V Guruprasad

Recent measurements of the Cosmic Microwave Background Anisotropy have provided evidence for the presence of oscillations in the angular power spectrum. These oscillations are a wonderful confirmation of the standard cosmological scenario…

Astrophysics · Physics 2007-05-23 Alessandro Melchiorri

Peculiar velocities encode rich cosmological information, but their transverse components are hard to measure. Here, we present the first observations of a novel effect of transverse velocities: the dipole signatures that they imprint on…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-16 Yan-Chuan Cai , John A. Peacock , Anna de Graaff , Shadab Alam

Anisotropic cosmological models have been gaining attention due to various observational hints of large-scale anisotropies. One of the most surprising evidences for the latter is the discovery of a dipole-like directional variation in…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-08 Boris Hoi-Lun Ng , Ming-Chung Chu

The recent three-year WMAP data have confirmed the anomaly concerning the low quadrupole amplitude compared to the best-fit \Lambda CDM prediction. We show that, allowing the large-scale spatial geometry of our universe to be…

Astrophysics · Physics 2008-12-18 L. Campanelli , P. Cea , L. Tedesco

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

We discuss the large scale polarization of the cosmic microwave background induced by the anisotropy of the spatial geometry of our universe. Assuming an eccentricity at decoupling of about $0.64 10^{-2}$, we find an average large scale…

Cosmology and Nongalactic Astrophysics · Physics 2010-03-18 Paolo Cea

Erickcek, Kamionkowski and Carroll proposed in 2008 that the dipole modulation of the CMB could be due to a very large scale perturbation of the field $\phi$ causing the primordial curvature perturbation. We repeat their calculation using…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 David H. Lyth

In the late 1990's, observations of 93 Type Ia supernovae were analysed in the framework of the FLRW cosmology assuming these to be `standard(isable) candles'. It was thus inferred that the Hubble expansion rate is accelerating as if driven…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-13 Roya Mohayaee , Mohamed Rameez , Subir Sarkar

The origin of small deviations from statistical isotropy in the Cosmic Microwave Background (CMB) - the so-called CMB anomalies - remains an open question in modern cosmology. In this work, we test statistical isotropy in Planck Data…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-09 C. Gimeno-Amo , F. K. Hansen , E. Martínez-González , R. B. Barreiro , A. J. Banday

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…

Astrophysics · Physics 2009-12-30 Thomas J. Loredo , Eanna E. Flanagan , Ira M. Wasserman

The Pierre Auger Observatory has recently reported the detection of a dipole anisotropy in the arrival directions of cosmic rays above 8 EeV with a post-trial significance of more than 5.2$\sigma$. This observation has profound consequences…

High Energy Astrophysical Phenomena · Physics 2018-08-30 Markus Ahlers

The first observations of the cosmic microwave background (CMB) from NASA's \emph{Wilkinson Microwave Anisotropy Probe} (WMAP) led to finding `alignment' anomalies not expected from fluctuations in the isotropic cosmological model. We study…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-03 Sanjeet Kumar Patel , Pavan Kumar Aluri , John P. Ralston

We study the Planck CMB temperature at different scales through its derivatives up to second order, which allows one to characterize the local shape and isotropy of the field. The problem of having an incomplete sky in the calculation and…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-22 A. Marcos-Caballero , E. Martínez-González , P. Vielva

We report results on an ``one-way light path'' laser diffraction experiment as a function of the laser beam alignment relative to the Earth's velocity vector obtained by COBE measurements of the Doppler shift in the cosmic microwave…

Astrophysics · Physics 2007-05-23 C. E. Navia , C. R. A. Augusto