|
|
|
|
|
Philip Lah |
|
"Measuring the Gas Content
of Distant Galaxies using the Optical Redshifts" |
|
A new technique has been used to measure in the distant past the gas content of galaxies, the fuel supply for star formation. Instead of trying to observe the weak radio HI 21-cm emission signal from each galaxy the signal from multiple galaxies has been coadded together using their observed optical positions and optical spectroscopic redshifts. The gas in star-forming galaxies at redshift z = 0.24 (a look-back time of ~3 billion years) and the gas in galaxies around Abell 370, a galaxy cluster at redshift z = 0.37 (a look-back time of ~4 billion years), have been measured. Additionally I will show that the coadding technique can be used to measure the HI gas in galaxies out to redshift z = 1.0 (a look-back time of ~8 billion years) using the SKA pathfinder telescopes of ASKAP and MeerKAT with the AAT again playing a critical role. |