Application of a Bayesian Method to Absorption Spectral-Line Finding in Simulated ASKAP Data
J. R. Allison A D , E. M. Sadler A B and M. T. Whiting CA Sydney Institute for Astronomy, School of Physics A28, University of Sydney, NSW 2006, Australia
B ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)
C CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW 1710, Australia
D Corresponding author. Email: jra@physics.usyd.edu.au
Publications of the Astronomical Society of Australia 29(3) 221-228 https://doi.org/10.1071/AS11040
Submitted: 28 August 2011 Accepted: 16 September 11 Published: 26 October 2011
Abstract
The large spectral bandwidth and wide field of view of the Australian SKA Pathfinder radio telescope will open up a completely new parameter space for large extragalactic HI surveys. Here we focus on identifying and parametrising HI absorption lines which occur in the line of sight towards strong radio continuum sources. We have developed a method for simultaneously finding and fitting HI absorption lines in radio data by using multi-nested sampling, a Bayesian Monte Carlo algorithm. The method is tested on a simulated ASKAP data cube, and is shown to be reliable at detecting absorption lines in low signal-to-noise data without the need to smooth or alter the data. Estimation of the local Bayesian evidence statistic provides a quantitative criterion for assigning significance to a detection and selecting between competing analytical line-profile models.
Keywords: methods: data analysis — methods: statistical — radio lines: galaxies
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