Modeling the Milky-Way Satellite galaxies

Understand

We revisit the Milky Way satellite problem using a semi-analytical model of galaxy formation and compare the predicted luminosity function to recent result from the SDSS.

• With cosmic photoionization, the luminosity function can be brought into broad agreement with the data between $-15< M_{V} <-2$.
• This improvement over previous semi-analytical model results (e.g., Benson et al.2002) is from our adoption of improved models for galaxy merger history and galaxy merging time-scales.
• The very faint satellites ($M_{v} > -5$) formed in halos with virial temperature over $10^{4}K$ (mass around $10^{9} M_{\odot}$ before accretion), but their baryon content are strongly suppressed by photoionization.