Speaker
Description
We present the latest results from the HIX galaxy survey, which studies a sample of the most HI-rich (for their optical luminosity) and HI-massive spiral galaxies in the local universe. Given their large and massive HI discs, their high redshift counterparts might be among the first galaxies, we will detect in HI beyond the currently observable redshift range. A detailed examination of the star formation activity, the spatially resolved HI morphology and kinematics, and the gas-phase metallicity of the HIX galaxies reveals that they have not recently accreted more gas than average local galaxies. Furthermore, they are also located on the star formation main sequence and are thus average star formers. However, large parts of the HI reservoirs of HIX galaxies are located outside the stellar disc, where no stars can be formed. This is due to a larger than average HI specific angular momentum, which allows HIX galaxies to stabilise their HI disc against more vigorous molecular gas and subsequent star formation. A comparison to semi-analytic models suggests that the elevated HI specific angular momentum is inherited from the elevated spin of the host dark matter halo.
During the examination of the HIX sample, the following questions arose: What do the average HI morphology and kinematics of an average local galaxy look like? How common are warped HI discs, HI-tails, HI column density depressions in galaxy centres, ...? The HI content of HI-rich galaxies is determined by the angular momentum properties of these galaxies; is this the case for all field galaxies at low redshifts? Does this allow us to predict HI masses of galaxies at higher redshifts solely from their kinematic properties? To understand these questions, we are currently compiling spatially resolved HI observations of an as large and diverse sample of galaxies as possible from the archives. We estimate that this will allow us to study the HI kinematics and morphology of a few hundreds of galaxies in a consistent way. First results of this new project will also be presented at the workshop.
| Wish list question? | 5. What do the properties of HI in the Galaxy and nearby galaxies lead us to expect at higher redshifts? |
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