1. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution1 Globular Clusters: The Dwarf Galaxy Contribution Eva K. Grebel Astronomisches Rechen-Institut (ARI) Center for Astronomy, Heidelberg University (ZAH) Heidelberg, Germany

2. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution2 Zinn 1985 –0.8 dex Halo disk/bulge bulge/disk GCs old halo GCs “young” halo GCs Sgr GCs Harris 1996 Mackey & Gilmore 2004 van den Bergh (1995): stronger trend with perigalactic distances

3. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution3 Mackey & van den Bergh 2005 Cumulative radial distribution of different subcomponents

4. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution4 Zinn 1993 Horizontal Branch Morphology vs. Metallicity: Age?

5. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution5 Horizontal Branch Morphologies and Young Halo Contributors Mackey & Gilmore 2004  t = 0 Gyr  t = 1.1 Gyr  t = 2.2 Gyr See also Harbeck et al. 2001

6. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution6 Horizontal Branch Morphologies and Young Halo Contributors Mackey & Gilmore 2004  t = 0 Gyr  t = 1.1 Gyr  t = 2.2 Gyr See also Harbeck et al. 2001

7. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution7 Horizontal Branch Morphologies and Young Halo Contributors Mackey & Gilmore 2004  t = 0 Gyr  t = 1.1 Gyr  t = 2.2 Gyr See also Harbeck et al. 2001

8. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution8 Glatt et al. 2007 SMC: Only nearby dwarf with only one, younger GC. (HST/ACS)

9. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution9 Buonanno et al. 1998 4 (out of 5) globular clusters in Fornax: ~ indistinguishable in age; as old as oldest Galactic globulars (relative age dating).

10. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution10 Mackey & Gilmore 2004 bulge/disk GCs old halo GCs “young” halo GCs Sgr GCs Salaris & Weiss 2002 Harris 1996 Age Difference vs. Metallicity Old halo: slight trend (towards bulge) Young halo: steeper trend (towards Sgr)

11. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution11 Sbordone et al. 2007 Lower [  /Fe] at a given [Fe/H] in dwarfs and their globulars (few exceptions, e.g., Hodge 1; NGC 121) Cf. inner/outer halo dichotomy (Carollo et al. 2007)

12. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution12 Mackey & Gilmore 2004Salaris & Weiss 2002 Narrow peak;  Age ~ –2 Gyr. Strongly peaked at  Age ~ M92. Younger tail (incl. CMa?) Bimodal; peaked at –3.25 and –0.75 Gyr.

13. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution13 Mackey & Gilmore 2004 Similarity of Core Radii of Young Halo and External GCs If dwarfs were accreted: would contribute mainly young halo GC; only 20 – 20% old halo GCs. Zinn 1993

14. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution14 Mackey & van den Bergh 2005 Tidal Radii for Clusters of Different Components R t : strongly correlated with a GC’s peri- galactic distance (van den Bergh 1994).

15. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution15 Gnedin & Ostriker 1997 “Vital Diagram” for Galactic Globular Clusters

16. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution16 Mackey & van den Bergh 2005 sharp edge Cores of dwarf galaxies? Half-light Radii vs. Absolute Magnitudes

17. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution17 Grebel 2002 Globular clusters are rare in dwarfs!

18. E. K. Grebel Globular Clusters: The Dwarf Galaxy Contribution18 Some points for discussion: o Young halo globulars (HB morph.) resemble dSph globulars BUT: a number with "old" HB morphologies o DSphs (and dIrrs) contain some of the youngest globulars known BUT: Also contain globulars as old as oldest Galactic GCs o Half-light and tidal radii of young halo GCs and GCs in dwarfs: Close similarity. Hint of accretion or effect of survivability in absence of major tidal disruption? o Overall metallicities of outer halo GCs and dwarf GCs: similar; low. o Lower [  /Fe] at given [Fe/H] in dwarf field stars and GCs. (Constrains number of accretion events)  GCs in MW with similar ratios: Assumed to be accreted (e.g., Sgr) BUT: Also (d)Irrs contain some GCs with enhanced [  /Fe]! P Accretion: consistent. But is it required? P Substructure problem; number, importance, time of accretion events P How can GCs form in dSphs in the first place? Why so rare?