Simple Cosmological Model With Relativistic Gas

Berredo-Peixoto, Guilherme de; Shapiro, Ilya L.; Sobreira, F.

doi:10.1142/s0217732305018104

Cited by 34 publications

(95 citation statements)

References 12 publications

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“…We generalized a previously constructed, simplified RRGbased cosmological model [6,8,9], made of WDM, a cosmological constant, baryons and photons by taking into account an out-of-equilibrium interaction within the baryon-photon fluid. Such interaction, characterized here by a single phenomenological parameter ξ , is supposed to be relevant before decoupling when the scattering rate ceases to be much higher than the Hubble rate and deviations from equilibrium are expected.…”

Section: Discussionmentioning

confidence: 99%

“…The new aspect of the present work is the interaction which we introduced phenomenologically in Eqs. (5) and (6). It is easy to see that Eq.…”

Section: Basic Equations Of the Interacting Rrg Modelmentioning

confidence: 93%

“…The pressures of the warm components and radiation in the above equations are described by the simplified equation of state [6] …”

Section: Basic Equations Of the Interacting Rrg Modelmentioning

confidence: 99%

“…To do so, we will use the Reduced Relativistic Gas (RRG) model [6,7]. This model is based on the assumption that all particles have equal kinetic energies.…”

Section: Introductionmentioning

confidence: 99%

“…The use of the RRG model substantially simplifies the formalism, such that all the complexity of the Boltzmann-Einstein system can be reduced to an effective equation of state (EoS) that interpolates between a pure radiative fluid and a pressureless matter fluid. Remarkably, the EoS of such a system is given by a simple algebraic formula [8,9] (see also [6] for a detailed derivation), which enables one to solve the Friedmann equation exactly (for the equilibrium case) and to obtain an explicit and transparent picture of the transition between the radiation phase in the early Universe and the dust phase in the late Universe. Indeed, the deviation from the Maxwell relativistic EoS is very small and therefore the quality of the RRG-based approximation can be evaluated as excellent [6].…”

Section: Introductionmentioning

confidence: 99%

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Interacting photon–baryon fluid, warm dark matter, and the first acoustic peak

et al. 2014

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The Reduced Relativistic Gas (RRG) model was introduced by A. Sakharov in 1965 for deriving the cosmic microwave background (CMB) spectrum. It was recently reinvented by some of us to achieve an interpolation between the radiation and dust epochs in the evolution of the Universe. This model circumvents the complicated structure of the Boltzmann-Einstein system of equations and admits a transparent description of warm-dark-matter effects. It is extended here to include, on a phenomenological basis, an out-of-equilibrium interaction between radiation and baryons which is supposed to account for relevant aspects of pre-recombination physics in a simplified manner. Furthermore, we use the tight-coupling approximation to explore the influence of both this interaction and of the RRG warmness parameter on the anisotropy spectrum of the CMB. The predictions of the model are very similar to those of the CDM model if both the interaction and the dark-matter warmness parameters are of the order of 10 −4 or smaller. As far as the warmness parameter is concerned, this is in good agreement with previous estimations on the basis of results from structure formation.

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Section: Discussionmentioning

confidence: 99%

“…The new aspect of the present work is the interaction which we introduced phenomenologically in Eqs. (5) and (6). It is easy to see that Eq.…”

Section: Basic Equations Of the Interacting Rrg Modelmentioning

confidence: 93%

“…The pressures of the warm components and radiation in the above equations are described by the simplified equation of state [6] …”

Section: Basic Equations Of the Interacting Rrg Modelmentioning

confidence: 99%

“…To do so, we will use the Reduced Relativistic Gas (RRG) model [6,7]. This model is based on the assumption that all particles have equal kinetic energies.…”

Section: Introductionmentioning

confidence: 99%