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Along the general framework of the gauge invariant perturbation theory developed in the papers [K. Nakamura, Prog. Theor. Phys. {\bf 110} (2003), 723; {\it ibid}, {\bf 113} (2005), 481.], we formulate the second order gauge invariant…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Kouji Nakamura

Both global dynamics and turbulence in magnetized weakly collisional cosmic plasmas are described by general magnetofluid equations that contain pressure anisotropies and heat fluxes that must be calculated from microscopic plasma kinetic…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 A. A. Schekochihin , S. C. Cowley , F. Rincon , M. S. Rosin

A correction to the Jeans stability criterion due to heat conduction is established for the case of high temperature gases. This effect is only relevant for relativistic fluids and includes an additional term due to a density gradient…

General Relativity and Quantum Cosmology · Physics 2016-06-16 A. R. Mendez , A. L. Garciia-Perciante , A. Sandoval-Villalbazo

This paper aims at studying the reliability of a few frequently raised but not proven arguments for the modeling of cold gas clouds embedded in or moving through a hot plasma and at sensitizing modelers to a more careful consideration of…

Astrophysics of Galaxies · Physics 2019-10-09 Bastian Sander , Gerhard Hensler

After an introduction to the problem of cosmological structure formation, we develop gauge invariant cosmological perturbation theory. We derive the first order perturbation equations of Einstein's equations and energy momentum…

Astrophysics · Physics 2010-12-09 Ruth Durrer

Electrons densities in different locations of our galaxy are obtained in pulsar astronomy by dividing the dispersion measure (DM) by the distance of the pulsar to Earth. The properties of the interstellar plasma are related to its heating.…

High Energy Astrophysical Phenomena · Physics 2023-12-05 Y. Ben-Aryeh

Increasingly accurate observations are driving theoretical cosmology toward the use of more sophisticated descriptions of matter and the study of nonlinear perturbations of FL cosmologies, whose governing equations are notoriously…

General Relativity and Quantum Cosmology · Physics 2015-05-27 Claes Uggla , John Wainwright

A simulation study is performed to investigate the dynamics of coupled Langmuir waves (LWs) and ion-acoustic waves (IAWs) in an unmagnetized plasma. The effects of dispersion due to charge separation and the density nonlinearity associated…

Plasma Physics · Physics 2010-04-29 S. Banerjee , A. P. Misra , P. K. Shukla , L. Rondoni

We investigate cosmological perturbations of f(G) gravity in the presence of a scalar field. Using the 1 + 3 covariant formalism, we present the energy overdensity perturbation equations responsible for large scale structure formation.…

General Relativity and Quantum Cosmology · Physics 2023-12-27 Albert Munyeshyaka , Joseph Ntahompagaze , Tom Mutabazi , Manasse. R Mbonye

We study cosmological perturbation spectra using the dynamical equations of gauge invariant perturbations with a generalized blue/red-shift term. Combined with the power-law index of cosmological background, {\nu}, we construct a parameter…

General Relativity and Quantum Cosmology · Physics 2012-11-08 Chonghong Li , Yeuk-Kwan E. Cheung

We calculate the evolution of linear density and temperature perturbations in a universe with dark matter, baryons, and radiation, from cosmic recombination until the epoch of the first galaxies. In addition to gravity, the perturbations…

Astrophysics · Physics 2010-12-09 Smadar Naoz , Rennan Barkana

We study the linear cosmological evolution of inelastic self-interacting dark matter in a two-component dark sector with a small mass splitting, assuming thermal initial conditions for the two species. We derive the coupled background and…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-28 Xin-Chen Duan , Yue-Lin Sming Tsai , Ziwei Wang

In recent years there has been a lot of interest in discussing frame dependences/independences of the cosmological perturbations under the conformal transformations. This problem has previously been investigated in terms of the covariant…

General Relativity and Quantum Cosmology · Physics 2018-03-14 Yunlong Zheng , Yicen Mou , Haomin Rao , Mingzhe Li

The Jeans stability criterium for gravitational collapse is examined for the case of an inert binary mixture in local equilibrium, neglectinq dissipative effects. The corresponding transport equations are established using kinetic theory…

Statistical Mechanics · Physics 2021-10-18 A. Sandoval-Villalbazo , A. R. Sagaceta-Mejia

We study the nonlinear propagation of electrostatic wave packets in a collisional plasma composed of strongly coupled ions and relativistically degenerate electrons. The equilibrium of ions is maintained by an effective temperature…

Plasma Physics · Physics 2012-02-24 A. P. Misra , P. K. Shukla

Using the covariant approach and conformal transformations, we present a gauge-invariant formalism for cosmological perturbations in generalized Einstein theories (GETs), including the Brans-Dicke theory, theories with a non-minimally…

Astrophysics · Physics 2010-11-01 Toshinari Hirai , Kei-ichi Maeda

The multi-fluid modelling of high-frequency waves in partially ionized plasmas has shown that the behavior of magnetohydrodynamics waves in the linear regime is heavily influenced by the collisional interaction between the different species…

Solar and Stellar Astrophysics · Physics 2018-04-04 David Martínez-Gómez , Roberto Soler , Jaume Terradas

We study the matter density fluctuations in the running cosmological constant (RCC) model using linear perturbations in the longitudinal gauge. Using this observable we calculate the growth rate of structures and the matter power spectrum,…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-13 A. M. Velasquez-Toribio

The nonlinear propagation of electromagnetic waves in pair plasmas, in which the electrostatic potential plays a very important but subdominant role of a "binding glue" is investigated. Several mechanisms for structure formation are…

Plasma Physics · Physics 2015-05-14 S. M. Mahajan , N. L. Shatashvili , V. I. Berezhiani

Collisional plasma shocks generated from supersonic flows are an important feature in many astrophysical and laboratory high-energy-density plasmas. Compared to single-ion-species plasma shocks, plasma shock fronts with multiple ion species…

Plasma Physics · Physics 2023-04-05 F. Chu , A. L. LaJoie , B. D. Keenan , L. Webster , S. J. Langendorf , M. A. Gilmore