The Progenitors of the Milky Way Stellar Halo: Big Bricks Favoured over
  Little Bricks
  We present a census of blue horizontal branch (BHB) and blue straggler (BS)
stars belonging to dwarf galaxies and globular clusters, and compare these
counts to that of the Milky Way stellar halo. We find, in agreement with
earlier studies, that the ratio of BS-to-BHB stars in these satellite
populations is dependent on stellar mass. Dwarf galaxies show an increasing
BS-to-BHB ratio with luminosity. In contrast, globular clusters display the
reverse trend, with N_BS/N_BHB (< 1) decreasing with luminosity. The faintest
(L < 10^5 L_Sun) dwarfs have similar numbers of BS and BHB stars (N_BS/N_BHB ~
1), whereas more massive dwarfs tend to be dominated by BS stars (N_BS/N_BHB ~
2-40). We find that the BS-to-BHB ratio in the stellar halo is relatively high
(N_BS/N_BHB ~ 5-6), and thus inconsistent with the low ratios found in both
ultra-faint dwarfs and globular clusters. Our results favour more massive
dwarfs as the dominant "building blocks" of the stellar halo, in good agreement
with current predictions from LambdaCDM models.
