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Fandiño, Mateus Arantes

University of British Columbia

Hydrogen intensity mapping is a new technique to map the three-dimensional distribution of matter in the universe. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is at the forefront of the development of intensity mapping and will produce the largest survey of the universe ever done. This dissertation describes my contributions to the calibration and analysis of CHIME data. The two types of amplifiers used in the telescope were characterized for their thermal complex gain susceptibility. In addition, a system of thermometers for the low-noise amplifiers was developed and deployed. The data is presented and its usefulness assessed. A thermal model for the amplitude of the telescope gains was developed based on gains extracted daily from bright point source transits. The model is effective in reducing the common-mode per-input variability (standard deviation) of the gains amplitude from 1.5% to 0.75% at the high end of the frequency band. The effect is smaller at the lower end of the band where the instrument thermal susceptibility is smaller. The model was tested by beam-forming on visibility data and the possibility of expansion of the model was assessed via singular value decomposition of the gains data. A program to cross-correlate the CHIME data with the Sloan quasar catalog was developed. This is done via a frequency stack on frequency-shifted beam-formed CHIME data. The existing codebase for sky simulations was expanded to allow for correlated tracers with different biases using the Zeldovich approximation. The analysis pipeline was expanded to allow for the generation of selection function-aware mock quasar catalogs, for the beam-forming of visibility data on arbitrary positions and for the frequency shifting and stacking of formed-beam spectra. A 13-σ detection of the cross-correlation signal was obtained. The detected signal shows a 4.6-σ deviation from zero frequency lag which might indicate a systematic difference between the redshift inferred from quasar emission lines relative to the redshifts of their host galaxies. The foreground filtering transfer function is estimated from simulations and used to estimate the un-filtered brightness of the HI-quasar cross-correlation signal at 68.6±5.4 μJy/beam.

Text

2022-10-20

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/82942

Physics

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/