Both Supernovae (SNe) and Baryon Acoustic Oscillations (BAO) surveys emerged as complementary probes of the expansion history of the universe in the last few decades. SNe Ia cosmology has reached the systematic limits in the optical surveys. The most frequently occuring SNe Type IIP are emerging as equally rich distance probes for the next generation larger surveys. In this thesis, I highlight the astrophysical observables of these events in the context of ROTSE III SN survey and using the ROTSE SNe IIP sample, I present calibration in the framework of expanding photosphere method (EPM) to use them as cosmological distance indicators and present the measurement of Hubble expansion in the low−z universe. The upcoming DESI experiment will obtain largest spectroscopic sample to explore the universe for the last 10 billion years through BAO precision measurements. The design sensitivity however requires full control of the systematics. I present an analysis of systematic effects of the spectroscopic performance on the cosmological signal using simulated spectra and galaxy sample for the DESI survey. By modeling the spectroscopic inefficiencies for the simulation samples of emission line galaxies, I estimate the systematic bias and uncertainty on the BAO scale measurement due to various observing conditions.
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Dhungana, Govinda, "Cosmological Distance measurements with ROTSE Supernovae IIP and Observational Systematics on DESI Emission Line Galaxy Clustering" (2018). Physics Theses and Dissertations. 4.