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We study the effect of weak lensing by cosmic (super-)strings on the anisotropies of cosmic microwave background (CMB). In developing a method to calculate the lensing convergence field due to strings, and thereby temperature and…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-19 Daisuke Yamauchi , Keitaro Takahashi , Yuuiti Sendouda , Chul-Moon Yoo

We compute the angular power spectrum of the $B$-modes of the weak-lensing shear in a spatially anisotropic spacetime. We find that there must also exist off-diagonal correlations between the $E$-modes, $B$-modes, and convergence that allow…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-13 Thiago S. Pereira , Cyril Pitrou , Jean-Philippe Uzan

The cosmic microwave background anisotropy is sensitive to the slope and amplitude of primordial energy density and gravitational wave fluctuations, the baryon density, the Hubble constant, the cosmological constant, the ionization history,…

We consider a proposed alternative to quantum gravity, in which the spacetime metric is treated as classical, even while matter fields remain quantum. Consistency of the theory necessarily requires that the metric evolve stochastically.…

General Relativity and Quantum Cosmology · Physics 2024-07-23 Jonathan Oppenheim , Andrea Russo

We report on an experimental active matter system with motion restricted to four cardinal directions. Our particles are magnetite-doped colloidal spheres driven by the Quincke electrorotational instability. The absence of a magnetic field…

Soft Condensed Matter · Physics 2025-11-17 Eavan Fitzgerald , Cécile Clavaud , Debasish Das , Isaac C. D. Lenton , Scott R. Waitukaitis

We discuss the cosmological implications of an extended Brans-Dicke theory presented recently, in which there is an energy exchange between the scalar field and ordinary matter, determined by the theory. A new mass scale is generated in the…

General Relativity and Quantum Cosmology · Physics 2016-11-30 Georgios Kofinas , Eleftherios Papantonopoulos , Emmanuel N. Saridakis

Todays astrometry has reached the micro-arcsecond level in angular measurements of celestial objects. The next generations of astrometric facilities are aiming at the sub-micro-arcsecond scale. Sub-micro-arcsecond astrometry requires a…

General Relativity and Quantum Cosmology · Physics 2025-10-07 Sven Zschocke

We consider the possibility that dark energy and baryons might scatter off each other. The type of interaction we consider leads to a pure momentum exchange, and does not affect the background evolution of the expansion history. We…

General Relativity and Quantum Cosmology · Physics 2020-02-24 Sunny Vagnozzi , Luca Visinelli , Olga Mena , David F. Mota

We study field equations for a weak anisotropic model on the tangent Lorentz bundle $TM$ of a spacetime manifold. A geometrical extension of General Relativity (GR) is considered by introducing the concept of local anisotropy, i.e. a direct…

General Relativity and Quantum Cosmology · Physics 2019-04-01 A. Triantafyllopoulos , P. C. Stavrinos

All observational evidence for dark matter and dark energy is so far exclusively gravitational. Hence, the dark sector may be equivalently described by a theory of the spacetime metric whose dynamics is affected by interactions with an…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-10 Santiago Agüí Salcedo , Thomas Colas , Lennard Dufner , Enrico Pajer

An open (having no physical boundaries) baryon symmetric system is considered in a flat space-time. We assume that a space is uniformly filled with electromagnetic radiation and material objects, and the system is isotropic in any inertial…

Astrophysics · Physics 2007-05-23 Anatoli Vankov

Several cosmic-ray observatories have provided a high accuracy map of the sky at TeV--PeV energies. The data reveals an O(0.1%) deficit from north galactic directions that peaks at 10 TeV and then evolves with the energy, together with…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Eduardo Battaner , Joaquin Castellano , Manuel Masip

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.…

Astrophysics · Physics 2009-11-10 Pankaj Jain , S. Sarala

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

We investigate the global texture model of structure formation in cosmogonies with non-zero cosmological constant for different values of the Hubble parameter. We find that the absence of significant acoustic peaks and little power on large…

Astrophysics · Physics 2009-10-31 Ruth Durrer , Martin Kunz , Alessandro Melchiorri

Working toward a model independent understanding of cosmic microwave background (CMB) anisotropies and their significance, we undertake a comprehensive and self-contained study of scalar perturbation theory. Initial conditions, evolution,…

Astrophysics · Physics 2009-09-25 Wayne Hu , Naoshi Sugiyama

We investigate measures of distance and redshift in cosmological space-times that admit a shear-free foliation, which we henceforth refer to as `quasi-Newtonian'. Space expands isotropically in this description, and small-scale…

General Relativity and Quantum Cosmology · Physics 2026-04-10 Asta Heinesen , Davide Fontana , Timothy Clifton

In this paper are discussed possible many body generalizations of the expanding locally anisotropic metric ansatz with respect to approximately Newtonian gravitational systems. This ansatz consistently describes local point-like matter…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-16 P. Castelo Ferreira

We present simple and accurate analytical formulae for the rates of Compton scattering by relativistic electrons integrated over the energy distribution of blackbody seed photons. Both anisotropic scattering, in which blackbody photons…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Andrzej A. Zdziarski , Patryk Pjanka

I consider the case of anisotropies in the Cosmic Microwave Background (CMB) from one single ordered perturbation source, or seed, existing well before decoupling between matter and radiation. Such structures could have been left by high…

Astrophysics · Physics 2009-10-31 Carlo Baccigalupi