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In this paper, we search the existence of invariant solutions of Bianchi type I space-time in the context of $f\left(R,T\right)$ gravity. The exact solution of the Einstein's field equations are derived by using Lie point symmetry analysis…

General Physics · Physics 2018-02-01 Anil Kumar Yadav , Ahmad T. Ali

We present a general study of the dynamical properties of Anisotropic Bianchi Universes in the context of Einstein General Relativity. Integrability results using Kovalevskaya exponents are reported and connected to general knowledge about…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Jerome Perez

We use a diffusion galactic model to analyze the end of the Galactic cosmic ray spectrum and its mixing with the extragalactic cosmic ray flux. We analyze the transition between Galactic and extragalactic components using two different…

Astrophysics · Physics 2007-10-18 C. De Donato , G. A. Medina-Tanco

We use our N\"other Symmetry Approach to study the Einstein equations minimally coupled with a scalar field, in the case of Bianchi universes of class A and B. Possible cases, when such symmetries exist, are found and two examples of exact…

General Relativity and Quantum Cosmology · Physics 2011-05-19 Salvatore Capozziello , Giuseppe Marmo , Claudio Rubano , Paolo Scudellaro

The strong evidence of new physics coming from atmospheric neutrino experiments has motivated a series of critical studies to test the robustness of the available flux calculations. In view of a more precise determination of the parameters…

High Energy Physics - Phenomenology · Physics 2009-10-31 G. Battistoni

In this paper, we investigate the evolution of cosmological perturbations within the context of Bianchi Type$-I$ spacetimes. We consider models containing viscous fluids with evolving cosmological (\LL) and Newtonian gravitational (G)…

General Relativity and Quantum Cosmology · Physics 2023-11-08 Alnadhief H. A. Alfedeel , Maye Elmardi , Amare abebe

Bianchi type III (BIII) metric is an interesting anisotropic model for studying cosmic anisotropy as it has an additional exponential term multiplied to a directional scale factor. Thus, the cosmological parameters obtained for this BIII…

General Relativity and Quantum Cosmology · Physics 2025-09-03 Pranjal Sarmah , Umananda Dev Goswami

We predict luminosity functions and number counts for extragalactic infrared sources at various wavelengths using the framework of our empirically based model. Comparisons of our galaxy count results with existing data indicate that either…

Astrophysics · Physics 2009-10-31 M. A. Malkan , F. W. Stecker

Homogeneous, nearly-isotropic Bianchi cosmological models are considered. Their time evolution is expressed as a complete set of non-interacting linear modes on top of a Friedmann-Robertson-Walker background model. This connects the…

General Relativity and Quantum Cosmology · Physics 2011-09-08 Andrew Pontzen , Anthony Challinor

We obtain a general exact solution of the Einstein field equations for the anisotropic Bianchi type I universes filled with an exponential-potential scalar field and study their dynamics. It is shown, in agreement with previous studies,…

General Relativity and Quantum Cosmology · Physics 2010-11-01 J. M. Aguirregabiria , A. Feinstein , J. Ibanez

We discuss interpretation of the cosmic infrared background (CIB) anisotropies detected by us recently in the Spitzer IRAC based measurements. The fluctuations are approximately isotropic on the sky consistent with their cosmological…

Astrophysics · Physics 2009-11-11 A. Kashlinsky , R. G. Arendt , J. Mather , S. H. Moseley

Axion production from astrophysical bodies is a topic in continuous development, because of theoretical progress in the estimate of stellar emission rates and, especially, because of improved stellar observations. We carry out a…

High Energy Physics - Phenomenology · Physics 2022-02-24 Luca Di Luzio , Marco Fedele , Maurizio Giannotti , Federico Mescia , Enrico Nardi

A one-parameter conformal invariance of Maxwell's equations allows the wavelengths of electromagnetic waves to change as they propagate, and do so even in otherwise field-free space. This produces an ambiguity in interpretations of stellar…

General Physics · Physics 2015-05-20 Carl E. Wulfman

In an anisotropic universe, observers not positioned at a point of special symmetry should observe cosmic parallax - the relative angular motion of test galaxies over cosmic time. It was recently argued that the non-observance of this…

Cosmology and Nongalactic Astrophysics · Physics 2009-12-30 Michele Fontanini , Mark Trodden , Eric J. West

We have examined the cosmological actions of LRS (Locally Rationally Symmetric) Bianchi type-I universe model in $f(R,T^\psi)$ gravity. For this, we have estimated the Hubble parameter, the effective equation of state parameter…

General Relativity and Quantum Cosmology · Physics 2026-01-07 Mohit Thakre , Praveen Kumar Dhankar , Safiqul Islam , Parbati Sahoo , Farook Rahaman , Behnam Pourhassan

The images of ultrahigh-energy cosmic ray sources get distorted, in an energy dependent way, by the effects of Galactic and extragalactic magnetic fields. These deflections can also affect the observed cosmic ray spectrum, specially when…

High Energy Astrophysical Phenomena · Physics 2022-03-02 Silvia Mollerach , Esteban Roulet

Bianchi type V bulk viscous fluid cosmological models are investigated. Using a generation technique (Camci {\it et al.}, 2001), it is shown that the Einstein's field equations are solvable for any arbitrary cosmic scale function. The…

General Relativity and Quantum Cosmology · Physics 2009-07-23 Anirudh Pradhan , Vandana Rai , R. S. Singh

The inverse problem of cosmic ray transport of ultra-high energy cosmic rays is considered. The analysis of Auger data on energy spectrum, energy dependence of mean logarithm of atomic mass number and its variance allows definite…

High Energy Astrophysical Phenomena · Physics 2017-01-05 V. N. Zirakashvili , S. I. Rogovaya , V. S. Ptuskin , E. G. Klepach

The wealth of data collected in the last few years thanks to the Pierre Auger Observatory and recently to the Telescope Array made the problem of the origin of ultra high energy cosmic rays a genuinely experimental/observational one. The…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Pasquale Blasi

In this work, we study some physical aspects of unitary evolution of Bianchi-I model. In particular, we study the behavior of the volume and the scale factor as a function of time for the Bianchi-I universe with ultra-relativistic fluid…

General Relativity and Quantum Cosmology · Physics 2016-01-28 Sridip Pal
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