Related papers: Response to Leahy's Comment on the Data's Indicati…
Nodland and Ralston (astro-ph/9704196) claim evidence for a wavelength-independent cosmic birefringence. Although it has been shown (astro-ph/9704247, astro-ph/9704263) that the data analysed did not support this conclusion, the possibility…
Eisenstein and Bunn have widely circulated a Comment (astro-ph/9704247) suggesting a non-standard null hypothesis in a test for cosmological birefringence. The Comment misrepresents the procedure used by Nodland and Ralston (B. Nodland and…
Measurements of the polarization angle and orientation of cosmological radio sources may be used to search for unusual effects in the propagation of light through the universe. Recently, Nodland and Ralston (astro-ph/9704196) have claimed…
A recent paper (Nodland and Ralston, PRL 78, 3043, astro-ph/9704196) claims to have detected evidence for birefringence in the propagation of radio waves across cosmological distances. In order to assess the statistical significance of…
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…
The measurement of the anisotropies of cosmic ray arrival direction provides important informations on the propagation mechanisms and on the identification of their sources. In this paper we report the observation of anisotropy regions at…
A numerical likelihood approach to the determination of cosmic ray anisotropies is presented which offers many advantages over other approaches. It allows a wide range of statistically meaningful hypotheses to be compared even when full sky…
We show that significant anisotropy in electromagnetic propagation generates a distinctive signature in the microwave background. The anisotropy may be determined by looking at the cross correlator of the $E$-mode and $B$-mode polarisation…
Important informations on the origin and the propagation mechanisms of cosmic rays may be provided by the measurement of the anisotropies of their arrival direction. In this paper the observation of anisotropy regions at different angular…
Radiation traversing the observable universe provides powerful ways to probe anisotropy of electromagnetic propagation. A controversial recent study claimed a signal of dipole character. Here we test a new and independent data set of 361…
We present a detailed statistical study of the observed anisotropy in radio polarizations from distant extragalactic objects. This anisotropy was earlier found by Birch (1982) and reconfirmed by Jain and Ralston (1999) in a larger data set.…
The "cosmological principle" was set up early without realizing its implications for the horizon problem, and almost entirely without support from observational data. Consistent signals of anisotropy have been found in data on…
Using the Bayesian theory of model comparison, a new cosmological model due to John and Joseph [M. V. John and K. Babu Joseph, Phys. Rev. D 61, 87304 (2000)] is compared with the standard \Omega_{\Lambda} \neq 0 cosmological model. Their…
We review evidence for a new phenomenon in the propagation of radio waves across the Universe, an anisotropic rotation of the plane of polarization not accounted for by conventional physics.
The cosmic radio dipole is an anisotropy in the number counts of radio sources, analogous to the dipole seen in the cosmic microwave background (CMB). Measurements of source counts of large radio surveys have shown that though the radio…
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…
The power spectrum of cosmic microwave background lensing is a powerful tool for constraining fundamental physics such as the sum of neutrino masses and the dark energy equation of state. Current lensing measurements primarily come from…
In the last decade, a number of experiments dealt with the problem of measuring the arrival direction distribution of cosmic rays, looking for information on the propagation mechanisms and the identification of their sources. Any deviation…
We report a systematic rotation of the plane of polarization of electromagnetic radiation propagating over cosmological distances. The effect is extracted independently from Faraday rotation, and found to be correlated with the angular…
Low energy string theory predicts the existence of an axion field which can lead to cosmic birefringence. We solve the electromagnetic wave equations in the presence of such an axion and a dilaton field in order to determine their effect on…