Speaker
Description
All HI surveys are affected by selection effects, which in some cases can be quite complex. To understand these biases and how they affect our understanding of how galaxies populate dark matter halos, we have modelled HI emission lines of the galaxies in the semi-analytic model of galaxy formation SHARK, built on the LCDM SURFS suite of $N$-body simulations. We use the latter to create a mock ALFALFA survey with the same selection function and instrumental effects as the real survey. We explored the long-standing problem of the over-production of low circular velocity galaxies, and found our simulated ALFALFA survey to reproduce the observed HI velocity width distribution very well, hence concluding that the discrepancies previously reported are due to the complex selection effects of HI surveys. We also found that these biases affect galaxies even at the dwarf galaxy regime. During this talk, I will present these results, and also show which biases might affect the upcoming HI surveys like WALLABY and DINGO, and how best to tackle them.
| Wish list question? | 4. How can HI dynamics be used to probe the connection between galaxies and their dark matter halos over cosmic time? |
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