The HIX Galaxy Survey: The most HI rich Galaxies in the Southern Hemisphere

When comparing the gas content of galaxies with their current star formation rate, it has been found that the gas consumption time scale is much smaller than the age of galaxies. In addition, the metallicity within galaxies is much smaller than expected from closed box modelling of galaxies. These discrepancies suggest that galaxies must replenish their gas reservoirs by accretion of metal-poor gas from the intergalactic medium. In order to investigate this process of gas accretion in more detail we target local galaxies that host an atomic hydrogen (HI) disc at least 2.5 times more massive than expected from their optical properties using scaling relations. For this sample of galaxies, we have been collecting a multiwavelength data set consisting of deep ATCA HI interferometry, ANU SSO 2.3m WiFeS optical integral field spectroscopy and publicly available photometry from GALEX (ultraviolet), WISE and 2MASS (both infrared). We find that these galaxies are normal star-forming spiral galaxies. However, their specific angular momentum is higher than in control galaxies, which allows these galaxies to support a massive HI disc. With the help of the HI interferometry and the optical IFU spectra, we are searching for signs of recent gas accretion. These signs may include among other things non-circular motion of HI, warped or lopsided HI discs, both of which can be identified through tilted-ring modelling of the HI disc or inhomogeneities in the IFU-based metallicity maps. In my talk I will first compare the HI rich galaxies to the control sample and the general galaxy population. I will then move on to the most HI massive galaxy in our sample and discuss its HI kinematics and its gas-phase oxygen abundance distribution in more detail. To conclude I will give an outlook on the more detailed HI kinematics of the remaining HI rich sample