Standard model foregrounds in nuclear and particle astrophysics

Nuclear astrophysics;Particle astrophysics;Gamma rays;Cosmic rays;Nucleosynthesis;Polarisation

Chakraborty, Nachiketa

关键词: Nuclear astrophysics;    Particle astrophysics;    Gamma rays;    Cosmic rays;    Nucleosynthesis;    Polarisation;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/45628/Nachiketa_Chakraborty.pdf?sequence=1&isAllowed=y

美国|英语

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

【 摘 要 】

Nuclear and particle astrophysics comprises of applying standard principles of nuclear and particle physics to astronomical systems and making predictions for observation. Also, extreme environments in astronomical systems often serve as a probe for re-evaluating fundamental principles of physics and astronomy. The research described here comprises of both these aspects of nuclear and particle astrophysics. There are two broad themes : primordial nucleosynthesis and cosmic gamma-ray sources. As a part of the first theme, the ``cosmological lithium problem'', and a possible nuclear physics solution to it is examined. The theoretical prediction of the abundance of Li7 produced in the big bang exceeds the observationally inferred abundance by a factor of 3-4, that is very difficult to explain within the Standard Model of particle physics and cosmology. The possibility of missed nuclear resonances in the network of nuclear reactions used to compute the theoretical primordial abundance is discussed. Three such candidate resonances are found prompting experiments to either find them or rule them out. In the light of recent experiments eliminating the most promising of these candidates, requirement of new physics beyond the Standard Model looms large as a a possible solution. In the second area of research, properties of cosmic gamma-ray emitting sources such as star forming galaxies and blazars are studied. The gamma-ray sky has contributions from these guaranteed sources and potentially others such as particle dark matter. In the light of this, gamma-rays properties of the guaranteed astronomical sources as spectral slope, photon count statistics and polarisation of X-rays and soft gamma-rays is studied in the hope of achieving the broad goal of understanding the underlying physics of radiative emission of these sources and hopefully disentangling these ``foregrounds'' from other exotic sources such as particle dark matter.