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From the Milky Way to Andromeda: A PAndAS View of Galactic Halos. Brendan McMonigal Supervisor - Geraint F. Lewis Sydney Institute for Astronomy School of Physics, The University of Sydney. Original image: Stephen Rahn (Flikr). Outline. A PAndAS Introduction Mapping the contamination
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From the Milky Way to Andromeda: A PAndAS View of Galactic Halos Brendan McMonigal Supervisor - Geraint F. Lewis Sydney Institute for Astronomy School of Physics, The University of Sydney Original image: Stephen Rahn (Flikr)
Outline • A PAndAS Introduction • Mapping the contamination • The Smooth Halo of M31 • A new MW Stream
PAndAS(Pan-Andromeda Archaeological Survey) MegaCam (~1 degree FOV) Canada-France-Hawaii Telescope CFHT – 3.6m on Hawaii
Andromeda & Triangulum (M31 & M33) M31 is a grand design spiral very similar to the MW, located at 780kpc. M33 has a mass ~1/10th that of the MW, located at a distance of 860kpc. Separated on the sky by ~15 degrees on the sky (physical separation of 230kpc) and M33 may be a bound satellite of M31, although it appears to be very undisturbed.
PAndAS Collaborators Alan McConnachie Lead PI Scott Chapman Mike Irwin Geraint Lewis Rodrigo Ibata Nicolas Martin Annette Ferguson PAndAS: The Pan-Andromeda Archaeological Survey
Expectations from Simulations 300kpc Bullock & Johnston (2005)
Full PAndAS CMD [Fe/H] = -1.91 [Fe/H] = -1.29 [Fe/H] = -0.71 [Fe/H] = -0.20 Ibata et al (2014)
PAndAS Contamination α β γ Martin et al (2013)
Before and... Martin et al (2013)
...After Martin et al (2013)
Source Identification Smoothed Density Significance η M31 Halo [Fe/H] Dwarf [Fe/H] Log(N) Half light radius Detections Martin et al (2013)
Significance Map Known Dwarf Known GC Martin et al (2013)
Detections Known Dwarf Known GC Algorithm Detection Martin et al (2013)
A New Extended Cluster Martin et al (2013)
The search for the smooth halo Metal Rich Metal Rich-ish Metal Poor-ish Metal Poor Ibata et al (2014)
The search for the smooth halo Metal Rich Metal Rich-ish Metal Poor-ish Metal Poor Ibata et al (2014)
Combined Map Ibata et al (2014)
Residuals Metal Rich Metal Rich-ish Metal Poor-ish Metal Poor Ibata et al (2014)
Profiling: Metal Poor Ibata et al (2014)
Profiling: Metal Poor-ish Ibata et al (2014)
Profiling: Metal Rich (and Rich-ish) Ibata et al (2014)
Substructure in the Milky Way Koposov et al (2012) SDSS-III
Substructure in the Milky Way Martin et al. (2014)
Take home points… • PAndAS: We now have the most comprehensive view of a galaxy halo out to 150kpc (as well as to 50kpc in M33) • Substructure: We see extensive substructure, consisting of streams and clumps, both in Andromeda and the MW. • Dwarf Population: We’ve uncovered a large populations of dwarf galaxies, but still not as many as expected from cosmological predictions (modulo gas physics). • Still to come: Globular Clusters (Nick), 3D structure (Anthony)