Speaker
Description
The Andromeda galaxy provides unique opportunities to study the structure of galaxies like our own Milky Way in great detail. I will report on the results from Project AMIGA (Absorption Maps In the Gas of Andromeda), which combines one of the most sensitive surveys to date for circumgalactic HI 21cm emission with searches for metal absorption using HST/COS ultraviolet spectroscopy of ~30 background AGNs projected within ~300 kpc (the virial radius) of M31. While the UV absorption measurements yield an extremely high covering factor of ionized metals about Andromeda, with ~90% covering factor of Si III, HI emission is nearly completely absent to $N({\rm HI}) \sim 2 \times 10^{17}\,{\rm cm}^{-2}$. Andromeda's CGM shows weaker absorption and HI content than most samples of galaxies at $z \sim 0.2$. The 21cm measurements, in particular, serve as both a guide and a warning for future proposed searches for CGM HI emission.
| Wish list question? | 7. What is the relationship between galaxies' HI reservoirs and their ionized circumgalactic media at z ~ 0? |
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