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Alan McConnachie Mike Irwin, Annette Ferguson, Nial Tanvir, Rodrigo Ibata, Geraint Lewis, Scott Chapman, Avon Huxor Alan McConnachie Mike Irwin, Annette.

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Presentation on theme: "Alan McConnachie Mike Irwin, Annette Ferguson, Nial Tanvir, Rodrigo Ibata, Geraint Lewis, Scott Chapman, Avon Huxor Alan McConnachie Mike Irwin, Annette."— Presentation transcript:

1 Alan McConnachie Mike Irwin, Annette Ferguson, Nial Tanvir, Rodrigo Ibata, Geraint Lewis, Scott Chapman, Avon Huxor Alan McConnachie Mike Irwin, Annette Ferguson, Nial Tanvir, Rodrigo Ibata, Geraint Lewis, Scott Chapman, Avon Huxor A Bird’s Eye View of M31 and its Satellite Galaxies IDM2004

2 The INT WFS of M31: Ibata et al. 2001 Ferguson et al. 2002 Irwin et al. 2004 Status as of July 2001 (58 pointings) Currently 165 pointings + M33 (21 pointings) + total of 15 other dwarf galaxies

3 Blue RGB Red RGB 125 kpc 95 kpc Faintest features: Faintest features have

4 Extent of the Stream: CFH12K Mosaic

5 McConnachie et al. 2003

6 Progress so far... Ibata et al. 2004 radial velocities for ~15 000 stars in 34 distinct fields concentrated on known substructure, general halo, and outer disk fields RVs accurate to ~5km/s McConnachie et al. 2004a Keck/DEIMOS radial velocity survey of M31

7 And VIII Ibata et al. 2004 First DIRECT measurement of the gravitational potential of a giant galaxy out to ~125 kpc:

8 Best fitting orbits: Ibata et al. 2004

9 The Satellite Galaxies of Andromeda: McConnachie et al. 2004b,c

10 Andromeda I & II TRGB = 20.40 TRGB = 20.13

11 An M31 All-Sky View: (Aitoff equal-area projection)

12 An M31 All-Sky View: (Aitoff equal-area projection)

13 An M31 All-Sky View: Preference for satellites to lie on near side of M31

14 The Line-of-Sight Probability Distribution Function Why are the satellites lop-sided? Why do they know about the Milky Way? Are they tracing the underlying potential?

15 Copious amounts of substructure: clue to formation history? First direct measure of dynamical mass of a galaxy over such a large distance range: Satellite distribution shows a strong anisotropy; tracers of underlying dark matter potential? Summary:


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