Colloquium on 27 October 2016
Estimating Redshifts from Distant HI Galaxies with Bayesian Statistics

Details

Title: Estimating Redshifts from Distant HI Galaxies with Bayesian Statistics
Speaker: Michelle Lochner
Date: Thursday, 27 October 2016
Time: 11:00 - 12:00
Venue: SAAO Auditorium

Abstract

The upcoming Square Kilometre Array (SKA) telescope will be the most sensitive radio telescope ever built, detecting the neutral hydrogen (HI) emission from up to a billion galaxies. However, HI emission from distant galaxies is intrinsically faint and easily lost in noise. Significant detection of the HI emission line is only expected for a small fraction of galaxies, making redshift estimation extremely difficult.
In this talk, I will discuss a new approach to redshift estimation from radio galaxies using Bayesian statistics. We perform parameter inference using the well-known HI line profile as a model. Using Bayesian model selection, we are able to robustly distinguish between an emission line and noise or RFI. This method would dramatically increase the number of well-characterised galaxies in the SKA catalogue, as well as providing the full probability distribution for each galaxy’s redshift. Preliminary results from a realistic SKA1-MID simulation indicate that we can recover the line profile parameters and a competitive redshift estimate for very low signal-to-noise lines, showing the promise of this new technique.
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