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Environmental Systematics and the Impact on 21-cm Epoch of Reionization Measurements

Description
The Epoch of Reionization (EoR) is the period in the evolution of the universe during which neutral hydrogen was ionized by the first luminous sources, and is closely linked to the formation of structure in the early universe. The Hydrogen Epoch of Reionization Array (HERA) is a radio interferometer currently…

The Epoch of Reionization (EoR) is the period in the evolution of the universe during which neutral hydrogen was ionized by the first luminous sources, and is closely linked to the formation of structure in the early universe. The Hydrogen Epoch of Reionization Array (HERA) is a radio interferometer currently under construction in South Africa designed to study this era. Specifically, HERA is dedicated to studying the large-scale structure during the EoR and the preceding Cosmic Dawn by measuring the redshifted 21-cm line from neutral hydrogen. However, the 21-cm signal from the EoR is extremely faint relative to galactic and extragalactic radio foregrounds, and instrumental and environmental systematics make measuring the signal all the more difficult. Radio frequency interference (RFI) from terrestrial sources is one such systematic. In this thesis, we explore various methods of removing RFI from early science-grade HERA data and characterize the effects of different removal patterns on the final 21-cm power spectrum. In particular, we focus on the impact of masking narrowband signals, such as those characteristic of FM radio and aircraft or satellite communications, in the context of the algorithms currently used by the HERA collaboration for analysis.
ContributorsWhitler, Lily (Author) / Jacobs, Daniel (Thesis director) / Bowman, Judd (Committee member) / Beardsley, Adam (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Modeling Surface Brightness of the HH 901 Jets in the Carina Nebula

Description
The purpose of this thesis is to accurately simulate the surface brightness in various spectral emission lines of the HH 901 jets in the Mystic Mountain Formation of the Carina Nebula. To accomplish this goal, we gathered relevant spectral emission line data for [Fe II] 12660 Å, Hα 6563 Å,…

The purpose of this thesis is to accurately simulate the surface brightness in various spectral emission lines of the HH 901 jets in the Mystic Mountain Formation of the Carina Nebula. To accomplish this goal, we gathered relevant spectral emission line data for [Fe II] 12660 Å, Hα 6563 Å, and [S II] 6720 Å to compare with Hubble Space Telescope observations of the HH 901 jets presented in Reiter et al. (2016). We derived the emissivities for these lines from the spectral synthesis code Cloudy by Ferland et al. (2017). In addition, we used WENO simulations of density, temperature, and radiative cooling to model the jet. We found that the computed surface brightness values agreed with most of the observational surface brightness values. Thus, the 3D cylindrically symmetric simulations of surface brightness using the WENO code and Cloudy spectral emission models are accurate for jets like HH 901. After detailing these agreements, we discuss the next steps for the project, like adding an external ambient wind and performing the simulations in full 3D.
ContributorsMohan, Arun (Author) / Gardner, Carl (Thesis director) / Jones, Jeremiah (Committee member) / Computer Science and Engineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05