Matterdensity perturbations can be generated from the nonlinear evolution of primordial tensor modes. At second order, we have a mixing between scalar, vector and tensor perturbation modes, we are interested in the secondorder scalar perturbations generated by linear tensor modes which are statistically independent of linear scalar modes. Working in the framework of a collisionless cold dark matter plus cosmological constant model and fixing our gauge to the comoving and synchronous one, there are two major objectives investigated in this thesis: First, we study the generation and evolution of secondorder energydensity perturbations arising from primordial gravitational waves and their imprint on the matter power spectrum by considering the effect of some high frequency primordial gravitational wave signals. Second, we study the nonGaussianity of these tensorinduced scalar perturbations, we calculate the Bispectrum as a general expression and in an equilateral shape configuration, These results will have an impact on the potential detectability of such tensorinduced scalar modes on largescale structure as well as cosmic microwave background anisotropy observables.
Matterdensity perturbations can be generated from the nonlinear evolution of primordial tensor modes. At second order, we have a mixing between scalar, vector and tensor perturbation modes, we are interested in the secondorder scalar perturbations generated by linear tensor modes which are statistically independent of linear scalar modes. Working in the framework of a collisionless cold dark matter plus cosmological constant model and fixing our gauge to the comoving and synchronous one, there are two major objectives investigated in this thesis: First, we study the generation and evolution of secondorder energydensity perturbations arising from primordial gravitational waves and their imprint on the matter power spectrum by considering the effect of some high frequency primordial gravitational wave signals. Second, we study the nonGaussianity of these tensorinduced scalar perturbations, we calculate the Bispectrum as a general expression and in an equilateral shape configuration, These results will have an impact on the potential detectability of such tensorinduced scalar modes on largescale structure as well as cosmic microwave background anisotropy observables.
Cosmological implications of tensorinduced scalar perturbations
ABDELAZIZ, MARIAM TAREK MOHAMED
2021/2022
Abstract
Matterdensity perturbations can be generated from the nonlinear evolution of primordial tensor modes. At second order, we have a mixing between scalar, vector and tensor perturbation modes, we are interested in the secondorder scalar perturbations generated by linear tensor modes which are statistically independent of linear scalar modes. Working in the framework of a collisionless cold dark matter plus cosmological constant model and fixing our gauge to the comoving and synchronous one, there are two major objectives investigated in this thesis: First, we study the generation and evolution of secondorder energydensity perturbations arising from primordial gravitational waves and their imprint on the matter power spectrum by considering the effect of some high frequency primordial gravitational wave signals. Second, we study the nonGaussianity of these tensorinduced scalar perturbations, we calculate the Bispectrum as a general expression and in an equilateral shape configuration, These results will have an impact on the potential detectability of such tensorinduced scalar modes on largescale structure as well as cosmic microwave background anisotropy observables.File  Dimensione  Formato  

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https://hdl.handle.net/20.500.12608/34461