1. Χαν ιά, August 9, 2004 Content and structure of galaxy halos Rodrigo Ibata Observatoire de Strasbourg

2. Χαν ιά, August 9, 2004 Outline Contents of halos: ● Dark matter ● Gas ● Dwarf galaxies ● Globular clusters ● Stellar halos - stellar halo substructure

3. Χαν ιά, August 9, 2004 Movie... Credit: Matthias Steinmetz

4. Χαν ιά, August 9, 2004 age in Gyr mass fraction Abadi, Navarro, Steinmetz & Eke 2003 Fine structure of simulated galaxies thin disk thick disk spheroid

5. Χαν ιά, August 9, 2004 Inner dark matter profile ● Navarro, Frenk & White (1997) ● Moore et al (1998) ● McGaugh, Rubin, de Blok (2001) ● Marchesini et al. (2002) ● De Blok, Bosma, McGaugh(2003) ● Klypin, Zhao Somerville (2002) Rotation curves of LSBs rise slower than predicted Situation OK for large galaxies.

6. Χαν ιά, August 9, 2004 Klypin et al. (1999) Moore et al. (2000) Bullock et al. (2000) Somerville (2001) Stoehr et al. (2002) Kravtsov et al. (2004) Credit B. Moore Missing satellites?

7. Χαν ιά, August 9, 2004 Extent of DM halos Fischer et al. 2000 Projected radius > 260 h-1kpc (95% CL) Weak lensing of faint background galaxies around L* foreground galaxies from 225 sq. deg.

8. Χαν ιά, August 9, 2004 Extent of satellites Prada et al. 2003 3000 satellites σ=120km/s @ 20kpc σ=60km/s @ 350kpc

9. Χαν ιά, August 9, 2004 Dwarf satellite galaxies Contents: ● Dark matter ● Dwarf galaxies (in some) ● Gas (in some) ● Stars ● Clusters (in some)

10. Χαν ιά, August 9, 2004 Star-formation history in dwarfs Mix of populations e.g. Carina dSph Monelli et al. (2003) Hernandez et al (2000)

11. Χαν ιά, August 9, 2004 From compilation by Mateo (1998) SFH of LG dwarfs

12. Χαν ιά, August 9, 2004

13. Are the majority of present-day dwarf galaxies the remnants of the population of cosmological proto-galactic building blocks that haven’t yet merged together?

14. Χαν ιά, August 9, 2004 Distribution of satellite galaxies Holmberg (1969) Zaritsky et al. (1997) Anisotropic to ~500kpc Sales & Lambas (2004) Penarrubia et al. (2002) Knebe et al. (2004)

15. Χαν ιά, August 9, 2004 Ghostly streams? Lynden-Bell & Lynden-Bell (1995) Palma, Majewski & Johnson (2002)

16. Χαν ιά, August 9, 2004 Distribution around M31 McConnachie et al. (2004)

17. Χαν ιά, August 9, 2004 M31 satellites in 3D McConnachie et al. (2004) So are dwarf galaxies cosmological building blocks or not???

18. Χαν ιά, August 9, 2004 The Milky Way stellar halo Ryan & Norris (1991), Chiba & Beers (2000): ● Metal-poor stars, [Fe/H] ~ -1.6 ● High velocity dispersion (141:106:94) km/s ● Small rotation: 30-50km/s ● Extended distribution with ● Axis ratio b/a ~ 0.6, but spherical beyond 15- 20kpc Is the Milky Way halo typical???

19. Χαν ιά, August 9, 2004 Do stellar halos differ? Harris (1996) Ryan & Norris (1991) Holland et al. (1996) Huchra et al. (1991)

20. Χαν ιά, August 9, 2004 Nearby galaxies – Mouhcine et al. (2004)

21. Χαν ιά, August 9, 2004 Clear colour trend Mouhcine et al. (2004) Increasing galaxy luminosity Increasing colour Increasing dispersion

22. Χαν ιά, August 9, 2004 Mouhcine et al. (2004) Expected for halo systems embedded in a dominant dark halo and formed in a single burst Dekel & Silk (1986) Stellar halo scaling relation

23. Χαν ιά, August 9, 2004 Globular cluster scaling relation M87: Elson & Santiago (1996) Strader, Brodie & Forbes (2004) Accretion does not drive the formation of GC systems in luminous galaxies! Bimodal globular cluster colour distribution

24. Χαν ιά, August 9, 2004 Composite halo – Zibetti et al (2004) Co-addition of 1047 edge-on galaxies g,r,i,z bands c/a ~ 0.6 Composite halo is red: old or metal-rich? 20 r exp

25. Χαν ιά, August 9, 2004 Zibetti & Ferguson (2004) Hubble UDF edge-on disk galaxy z = 0.32 b/a ~ 0.6 SB ~ 28-29 mag/arcsec^2 Peculiar colours! (i-z)~0.5, (V-i)~0.7)

26. Χαν ιά, August 9, 2004 A spheroid-less galaxy? M33 surface brightness profile: i-band surface photometry out to R ~ 35' profile extended to R ~ 60' using star counts V~31 mag arcsec -2 Ferguson et al. 2004

27. Χαν ιά, August 9, 2004 Halo substructure Malin 1979 44% of field E’s may have shells Kormendy & Djorgovski 1989 Forbes et al. 2003

28. Χαν ιά, August 9, 2004 The Local Group Majewski et al. (2003) (Credit: HIPASS & CSIRO) Ibata et al. (1994, 2001)

29. Χαν ιά, August 9, 2004 Further structures in M-giants Rocha-Pinto et al. (2004) Related to Monoceros structure? Newberg et al. (2001) or Galactic Ring? Ibata et al. (2003), Yanny et al. (2003) or Canis Major dwarf? Martin et al. (2004)

30. Χαν ιά, August 9, 2004 Blue RGB Red RGB 125 kpc 95 kpc faintest features have  V ~ 28-32 mag/” ! M31: an easier target! With: Scott Chapman, Annette Ferguson, Avon Huxor, Mike Irwin, Rachel Johnson, Geraint Lewis, Alan McConnachie & Nial Tanvir

31. Χαν ιά, August 9, 2004 Colour (metallicity) map of M31 Giant stream G1 clump fluff Northern spur Northern blob Plus other fainter structures... Eastern shelf Green Bank HI map Thilker et al 2004

32. Χαν ιά, August 9, 2004 What is the Origin of the Stellar Substructure at Large Radius in M31? ● satellite accretion as predicted by hierarchical galaxy formation theories? – one large system that has survived many orbits? – many smaller systems? – connection to known M31 satellites? ● warped/perturbed/flared outer disk? M31 is close enough (780 kpc) that radial velocities of individual RGB stars possible with DEIMOS (Keck-2) target CaII triplet in brightest giant stars (20.5 < i’ < 22) 0.31 Å/pix resolution, S/N~10 5-10 km/s velocity accuracy

33. Χαν ιά, August 9, 2004 NGC 205 Loop Progress to date: (sep ‘02, ‘03) spectra for ~15000 stars lying in 26 distinct fields target known substructure as well as the general halo and outer disk

34. Χαν ιά, August 9, 2004 Splat! ● Giant stream in process of disappearing! ● Providing metal- rich stars to M31 halo ● Inner M31 halo is not pristine... Ibata et al. (2004)

35. Χαν ιά, August 9, 2004 Conclusions New instruments/surveys allowing new rich view on halos Halos are no longer just seen in simulations! Dwarf galaxies place strong constraints on theory: (spatial distribution, ages, kinematics, chemistry) Interesting new results on halo stars from SDSS, HST and wide-field cameras: ubiquitous (red?) stellar halos? stellar halo/GC scaling relations? Substructure preponderant in inner regions of halos Much substructure at disk/halo transition region: some fraction formed by accretion?