WALLABY: Local Group Science

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WALLABY Local Group Science

• Emma Ryan-Weber

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Credit Mario Mateo
A test bed for galaxy formation and evolution
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Observed mass function before new discoveries

• Simon Geha (2007)

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Leo T in HIPASS
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ASKAP will be first blind survey of HI in the
Local Group to be conducted with an
interferometer. NOT having zero-spacing data
provides a significant advantage.
GMRT observations of Leo T Sensitivity5.2mJy/beam
/channel Channel width 1.65 km/s 30 beam
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Outstanding Questions

• Leo T doesnt fit the idea that reionization
  surpressed star formation in low mass dwarfs,
  although late accretion of gas is possible in
  relatively isolated systems (Ricotti et al.
  2007). Is Leo T a one off, or the tip of the
  iceberg?
• How do galaxies retain/gain gas and form stars?
• As we move further from the zone of destruction
  -- beyond 250- 350 kpc from the Milky Way/M31 --
  do we find more gas-rich dwarfs with Mhalo107
  Msun ?
• Is there a common minimum halo mass for SF?
• Is a galaxys SF history dominated by initial
  conditions (total mass, baryon fraction), or
  distance to the nearest spiral?
• Are there any starless galaxies? (The Local Group
  would be the best place to find them - lowest
  star formation efficiencies)

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A minimum dark matter halo mass (107
Msun)? Belokurov et al. (2007)