Central mass and luminosity of Milky Way satellites in the LCDM model

Abstract

It has been pointed out that the Galactic satellites all have a common mass around 1e7 Msun within 300 pc (M03), while they span almost four order of magnitudes in luminosity (Mateo et al. 1993, Strigari et al. 2008). It is argued that this may reflect a specific scale for galaxy formation or a scale for dark matter clustering. Here we use numerical simulations coupled with a semi-analytic model for galaxy formation, to predict the central mass and luminosity of galactic satellites in the LCDM model. We show that this common mass scale can be explained within the Cold Dark Matter scenario when the physics of galaxy formation is taken into account. The narrow range of M03 comes from the narrow distribution of circular velocities at time of accretion (peaking around 20 km/s) for satellites able to form stars and the not tight correlation between halo concentration and circular velocity. The wide range of satellite luminosities is due to a combination of the mass at time of accretion and the broad distribution of accretion redshifts for a given mass. This causes the satellites baryonic content to be suppressed by photo-ionization to very different extents. Our results favor the argument that the common mass M03 reflects a specific scale (circular velocity ~ 20 km/s) for star formation.

5 pages, 3 figures. References added, discussion enlarged, new version of Figure 3. Minor changes to match the version accepted for publication on ApJ Letters

References in corpus (9)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Galaxy Groups in the SDSS DR4: I. The Catalogue and Basic Properties
• Concentration, Spin and Shape of Dark Matter Haloes as a Function of the Cosmological Model: WMAP1, WMAP3 and WMAP5 results
• Massloss of galaxies due to a UV-background
• A common mass scale for satellite galaxies of the Milky Way
• The Tidal Evolution of Local Group Dwarf Spheroidals
• The Luminosity Function of the Milky Way Satellites
• A fitting formula for the merger timescale of galaxies in hierarchical clustering
• The Hierarchical Build-Up of Massive Galaxies and the Intracluster Light since z=1

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• Could the Fermi-LAT detect gamma-rays from dark matter annihilation in the dwarf galaxies of the Local Group?
• On the Size Evolution of a Galactic Disk in Hierarchical Merging of Cold Dark Matter Halos