Speaker
Description
I will present our main discoveries regarding the dynamics of HI-rich ultra diffuse galaxies (UDGs). Using a set of interferometric observations and a state-of-the-art 3D fitting technique we have derived reliable rotation velocities for a sample of seven isolated UDGs.
Surprisingly, these galaxies have very low circular velocities given their baryonic masses, which makes them shift off from the Baryonic Tully-Fisher relation (BTFR), suggesting fundamental differences between the formation of HI-rich UDGs and other disc galaxies. Moreover, their position in the BTFR matches the expectations of galaxies with a baryon fraction equal to the cosmological value, making these galaxies compatible with having no missing baryons, which sets important constraints on feedback processes at dwarf scales. The rotation velocities we derive also allow us to make an estimation of the dynamical mass of our HI-rich UDGs, revealing a low dark matter content. Yet, even with this set of unusual properties, they follow the same specific angular momentum-stellar mass relation as other galaxies.
| 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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