UBC Undergraduate Research

On Bayesian Baseline Removal and Signal Extraction Methods in Astronomy Liu, Ruihan Henry


Signals in radio astronomy are often accompanied with strong instrumental effects. These ”baseline” instrumental effects may affect the detection of real astrophysical signals, such as absorption and emission lines. A recent paper published in Nature has raised the possibility of life on Venus through a claimed detection of phosphine (PH3) gas absorption lines in the Venusian atmosphere. In this thesis, we utilize Bayesian marginalization methods to perform a re-analysis of the original observations of Venus using data from the James Clerk Maxwell Telescope (JCMT) and the Atacama Large Millimeter Array (ALMA). We find a signal detection in the James Clerk Maxwell Telescope data, but no phosphine absorption line feature in the higher resolution data from the Atacama Large Millimeter Array. We therefore conclude that the phosphine absorption line is not present as originally claimed. We further expand upon the methods used in this specific implementation, and discuss other applications of Bayesian signal extraction methodology.

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