Fundamental physics from observations of the early universe

Physical Cosmology;Early Universe;Fundamental Constants;21-cm Cosmology;Cosmic Microwave Background;Second Order Perturbation Theory;Cosmic Strings

Khatri, Rishi

关键词: Physical Cosmology;    Early Universe;    Fundamental Constants;    21-cm Cosmology;    Cosmic Microwave Background;    Second Order Perturbation Theory;    Cosmic Strings;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/16725/Khatri_Rishi.pdf?sequence=2&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The current experiments like Planck and future CMB, 21-cm and other largescale structure surveys willenable cosmologyto answer some of thefundamental questions in physics. The linear perturbation theory may not beaccurate enough to interpret the observations fromPlanck and future CMBexperiments. Second order effects may in particular be important inconstraining the non-Gaussianity in the initial conditions of theUniverse. Inhomogeneities in recombination and reionization amplify theperturbations in the underlying matter density and the resulting secondorder effects may be important. I calculate the bispectrum due to these second order effects and find that they are not an important source of confusion with the primordial non-Gaussianities. 21-cm observations of the era between the recombination and reionization will provide a wealth of data in the future. I study what we can learn about fundamental physics fromthese observations. In particular I calculate the constraints we might get from the future data on the existence and properties of cosmic strings, a prediction of GUT and superstring theories, and the variation of fundamental constants.