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This work examines the cosmological implications of two functional forms of $f(R,T) = R + \alpha T^n$ gravity: for two different value of $n $ where $n=1$ and $n\neq 1$, and $\alpha$ and $n$ are free parameters. The modified Friedmann…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-24 Mustapha Lamaaoune

In this paper, the effect of electromagnetic field has been investigated on the spherically symmetric collapse with the perfect fluid in the presence of positive cosmological constant. Junction conditions between the static exterior and…

General Relativity and Quantum Cosmology · Physics 2009-11-05 M. Sharif , G. Abbas

We investigate the space-time dependence of electromagnetic fields produced by charged participants in an expanding fluid. To address this problem, we need to solve the Maxwell's equations coupled to the hydrodynamics conservation equation,…

High Energy Physics - Theory · Physics 2023-11-23 Ashutosh Dash , Ankit Kumar Panda

If spacetime undergoes quantum fluctuations, an electromagnetic wavefront will acquire uncertainties in direction as well as phase as it propagates through spacetime. These uncertainties can show up in interferometric observations of…

General Relativity and Quantum Cosmology · Physics 2016-11-15 Y. Jack Ng

A case of non-minimal couplings between gravity and electromagnetic fields is presented. The field equations are worked out in the language of exterior differential forms. An exact charge screening class of solutions is given with a…

General Relativity and Quantum Cosmology · Physics 2020-12-02 Tekin Dereli , Yorgo Senikoglu

The coupling of the electromagnetic field to gravity is an age-old problem. Presently, there is a resurgence of interest in it, mainly for two reasons: (i) Experimental investigations are under way with ever increasing precision, be it in…

General Relativity and Quantum Cosmology · Physics 2016-12-07 Friedrich W. Hehl , Yuri N. Obukhov

Starting from Jefimenko's equations, we consider the multipole expansions of electric and magnetic fields for a confined system of charges and currents. We analyze and comment on the calculus of radiated power, on the consistent use of…

Classical Physics · Physics 2009-10-08 C. Vrejoiu , R. Zus

A model of nonlinear electrodynamics with a dimensional parameter $\beta$ is considered. Electromagnetic fields are the source of the gravitation field and inflation of the universe. We imply that the universe is filled by stochastic…

General Relativity and Quantum Cosmology · Physics 2017-05-08 S. I. Kruglov

The interplay among the spectrum, geometry and magnetic field in tubular neighbourhoods of curves in Euclidean spaces is investigated in the limit when the cross section shrinks to a point. Proving a norm resolvent convergence, we derive…

Mathematical Physics · Physics 2015-06-15 David Krejcirik , Nicolas Raymond

Recent experimental results from supernovae Ia observations have been interpreted to show that the rate of expansion of the universe is increasing. Other recent experimental results find strong indications that the universe is ``flat.'' In…

Astrophysics · Physics 2021-11-03 George A. Baker

Despite impressive phenomenological successes, cosmological models are incomplete without an understanding of what happened at the big bang singularity. Maxwell electrodynamics, considered as a source of the classical Einstein field…

General Relativity and Quantum Cosmology · Physics 2017-02-17 A. Övgün

If the conformal invariance of electromagnetism is broken during inflation, then primordial magnetic fields may be produced. If this symmetry breaking is generated by the coupling between electromagnetism and a scalar field---e.g. the…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-29 Robert R. Caldwell , Leonardo Motta , Marc Kamionkowski

Here, we analyze the primordial magnetic field transition between a radiative and a matter-dominated universe. The gravitational structure formation affects its evolution and energy spectrum. The structure excitation can trigger magnetic…

Astrophysics · Physics 2009-11-10 Grazyna Siemieniec-Ozieblo

We propose and construct a two-parameter perturbative expansion around a Friedmann-Lema\^{i}tre-Robertson-Walker geometry that can be used to model high-order gravitational effects in the presence of non-linear structure. This framework…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-15 Sophia R. Goldberg , Timothy Clifton , Karim A. Malik

We show that in the realm of general relativity a non minimal coupling between the electromagnetic and the gravitational fields may produce an era of accelerated expansion.

General Relativity and Quantum Cosmology · Physics 2019-06-26 M. Novello , A. E. S. Hartmann

In this paper, we investigate the dynamics of the universe on the background of f-essence when a non-minimal coupling with gravity. Field equations are obtained and using the Noether theorem, explicit forms of the coupling function and the…

General Physics · Physics 2017-05-26 Tolkynay Myrzakul , Ertan Gudekli , Shynaray Myrzakul , Ratbay Myrzakulov

Magnetic fields appear wherever plasma and currents can be found. As such, they thread through all scales in Nature. It is natural, therefore, to suppose that magnetic fields might have been formed within the high temperature environments…

Cosmology and Nongalactic Astrophysics · Physics 2012-08-16 Dai G. Yamazaki , Toshitaka Kajino , Grant J. Mathew , Kiyotomo Ichiki

The electromagnetic field near a rotating black hole is being explored in educational style here. By employing analytic solutions for electrovacuum fields, we plot the surfaces of constant flux and we show how the field is dragged around…

Astrophysics · Physics 2007-05-23 Z. Budinova , M. Dovciak , V. Karas , A. Lanza

The earlier developed algorithm for constructing a self-conjugate Hamiltonian in the \eta-representation for Dirac particles interacting with a general gravitational field is extended to the case of electromagnetic fields. This Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2011-11-07 M. V. Gorbatenko , V. P. Neznamov

The quantum field theory in the presence of classical background electromagnetic fields is reviewed. We give a pedagogical introduction to the Feynman-Furry method of describing non-perturbative interactions with very strong electromagnetic…

High Energy Physics - Phenomenology · Physics 2011-07-19 Alexander V. Kurilin