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Title: Alfvén wave in higher dimensional space time

Abstract

Following the wellknown spacetime decomposition technique as applied to (d+1) dimensions we write down the equations of magnetohydrodynamics (MHD) in a spatially flat generalised FRW universe. Assuming an equation of state for the background cosmic fluid we find solutions in turn for acoustic waves and also for Alfven waves in a warm (cold) magnetised plasma. Interestingly the different plasma modes closely resemble the flat space counterparts except that here the field variables all redshift with their time due to the expansion of the background. It is observed that in the ultrarelativistic limit the field parameters all scale as the free photon. The situation changes in the prerelativistic limit where the frequencies change in a bizarre fashion depending on initial conditions. It is observed that for a fixed magnetic field in a particular medium the Alfven wave velocity decreases with the number of dimensions, being the maximum in the usual 4D. Further for a fixed dimension the velocity attenuation is more significant in dust compared to the radiation era. We also find that in an expanding background the Alfven wave propagation is possible only in the high frequency range, determined by the strength of the external magnetic field, the mass densitymore » of the medium and also the dimensions of the spacetime. Further it is found that with expansion the cosmic magnetic field decays more sharply in higher dimensional cosmology, which is in line with observational demand.« less

Authors:
;
Publication Date:
OSTI Identifier:
22273249
Resource Type:
Journal Article
Journal Name:
Journal of Cosmology and Astroparticle Physics
Additional Journal Information:
Journal Volume: 2009; Journal Issue: 09; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALFVEN WAVES; ASTROPHYSICS; ATTENUATION; COMPARATIVE EVALUATIONS; COSMIC DUST; COSMOLOGY; DENSITY; EQUATIONS OF STATE; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; MATHEMATICAL SOLUTIONS; PHOTONS; PLASMA; RED SHIFT; RELATIVISTIC RANGE; SOUND WAVES; SPACE-TIME; UNIVERSE; VELOCITY

Citation Formats

Panigrahi, D., Das, Ajanta, and Chatterjee, S., E-mail: dibyendupanigrahi@yahoo.co.in, E-mail: ajanta.das@heritageit.edu, E-mail: chat_sujit1@yahoo.com. Alfvén wave in higher dimensional space time. United States: N. p., 2009. Web. doi:10.1088/1475-7516/2009/09/004.
Panigrahi, D., Das, Ajanta, & Chatterjee, S., E-mail: dibyendupanigrahi@yahoo.co.in, E-mail: ajanta.das@heritageit.edu, E-mail: chat_sujit1@yahoo.com. Alfvén wave in higher dimensional space time. United States. https://doi.org/10.1088/1475-7516/2009/09/004
Panigrahi, D., Das, Ajanta, and Chatterjee, S., E-mail: dibyendupanigrahi@yahoo.co.in, E-mail: ajanta.das@heritageit.edu, E-mail: chat_sujit1@yahoo.com. 2009. "Alfvén wave in higher dimensional space time". United States. https://doi.org/10.1088/1475-7516/2009/09/004.
@article{osti_22273249,
title = {Alfvén wave in higher dimensional space time},
author = {Panigrahi, D. and Das, Ajanta and Chatterjee, S., E-mail: dibyendupanigrahi@yahoo.co.in, E-mail: ajanta.das@heritageit.edu, E-mail: chat_sujit1@yahoo.com},
abstractNote = {Following the wellknown spacetime decomposition technique as applied to (d+1) dimensions we write down the equations of magnetohydrodynamics (MHD) in a spatially flat generalised FRW universe. Assuming an equation of state for the background cosmic fluid we find solutions in turn for acoustic waves and also for Alfven waves in a warm (cold) magnetised plasma. Interestingly the different plasma modes closely resemble the flat space counterparts except that here the field variables all redshift with their time due to the expansion of the background. It is observed that in the ultrarelativistic limit the field parameters all scale as the free photon. The situation changes in the prerelativistic limit where the frequencies change in a bizarre fashion depending on initial conditions. It is observed that for a fixed magnetic field in a particular medium the Alfven wave velocity decreases with the number of dimensions, being the maximum in the usual 4D. Further for a fixed dimension the velocity attenuation is more significant in dust compared to the radiation era. We also find that in an expanding background the Alfven wave propagation is possible only in the high frequency range, determined by the strength of the external magnetic field, the mass density of the medium and also the dimensions of the spacetime. Further it is found that with expansion the cosmic magnetic field decays more sharply in higher dimensional cosmology, which is in line with observational demand.},
doi = {10.1088/1475-7516/2009/09/004},
url = {https://www.osti.gov/biblio/22273249}, journal = {Journal of Cosmology and Astroparticle Physics},
issn = {1475-7516},
number = 09,
volume = 2009,
place = {United States},
year = {Tue Sep 01 00:00:00 EDT 2009},
month = {Tue Sep 01 00:00:00 EDT 2009}
}