The Galaxy Evolution Project and the SAMI/Hector Survey track the evolution and build-up of the matter in the form of ionised gas and the stars, as well as in the space between galaxies (called the intergalactic medium). The ASKAP Surveys provide the remaining pieces of the puzzle – they track the build-up of matter in the form of neutral gas over the past 7-8 billion years.

Neutral hydrogen gas provides the reservoir of material from which new stars can form in galaxies as they evolve over cosmic time. ASTRO 3D researchers are using the Australian SKA Pathfinder (ASKAP) radio telescope to map out the cosmic distribution of neutral hydrogen (HI) in unprecedented detail via three different but interlinked surveys.

WALLABY

Led by CI Lister Staveley-Smith and PI Baerbel Koribalski, this Survey will cover two-thirds of the sky and is expected to detect the 21cm HI emission line from up to 600,000 galaxies, looking back 2 billion years in cosmic time.

In 2018, a series of WALLABY Early Science papers were submitted for publication, based on ASKAP-12 observations of four 30-square-degree fields. Comprehensive kinematic analysis of six WALLABY galaxies has been completed by PhD student Tristan Reynolds. Dr Karen Lee-Waddell looked at interacting NGC 7232 galaxy group which features tidal HI streams and clouds. PhD student Ahmed Elagali analysed the nearby spiral galaxy NGC 1566.

The WALLABY source-finding group continued to improve the 3D Source Finding Application (SoFiA) and is exploring options for parallelisation for fast processing on Pawsey supercomputers.

DINGO

The Deep Investigations of Neutral Gas Origins (DINGO) survey (led by AI Martin Meyer) is studying the evolution of galaxies and the gas-rich Universe over the past 4 billion years.

This is being achieved through a combination of direct galaxy-by-galaxy analysis in the nearby Universe and statistical stacking studies at higher redshifts. The HI emission line data from DINGO will be combined with extensive multiwavelength data available in the target fields to understand the connections between gas content, stellar populations and star formation history, and the underlying dark matter distribution.

Pilot phase I data from DINGO has been processed and released into the CSIRO ASKAP Science
Data Archive (CASDA).

FLASH

CI Elaine Sadler leads the FLASH Survey, which is searching for the 21cm HI line in absorption against the bright continuum sources across the whole southern sky. The Survey will probe the neutral gas content of several hundred individual galaxies between 4 and 8 billion years ago, where the HI emission line is too weak to be detectable in even the deepest ASKAP surveys.

Much of the focus of the team has been multi-wavelength follow-up observations of galaxies where the team’s ASKAP commissioning observations detected HI in the redshift range z = 0.4 to 1. In particular, a paper by AI James Allison et al. used the Atacama Large Millimetre Array (ALMA) to detect a rare example of redshifted 12CO (2-1) absorption in the z=0.44 radio galaxy PKS B1740-517, providing us with a detailed picture of the cold interstellar medium within this recently-triggered young radio galaxy.

The FLASH team has now begun a new program of radio observations with the full 36-antenna ASKAP array.