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Katharina Lutz

Galaxies host huge reservoirs of atomic hydrogen (HI). These HI clouds fuel smaller clouds of molecular hydrogen, which in turn form stars. When comparing the amount of gas that is transformed into stars with the total amount of gas available in galaxies, it is found that all available gas would be consumed within approximately 3 Billion years. This, however, is in contradiction to the average age of galaxies, which is approximately 10 Billion years. From that fact we can conclude that galaxies need to replenish their gas content to be able to keep on forming stars and by today it is common agreement that this is done via accretion. Nevertheless, the physical mechanisms behind accretion onto galaxies are not yet clear. In my PhD thesis I will observe the HI mass and velocity distribution of a sample of galaxies with exceptionally large HI content making use of the Australian Telescope Compact Array (ATCA) in order to search for clues of how accretion works.

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