Kauffmann, White, Guidordoni 1994
Kauffmann, White, Guidordoni 1994
Klypin et al 1999
Moore et al. 1999
Satellites of "Local Group": 1.5Mpc/h sphere
Z=0 
Z=10 Forming galaxy
Z=5 Forming galaxy
Statistics of satellites: Klypin et al. 1999 
the same: Moore et al 1999
| Within 570kpc from either MW or M31 there are satellites dwarf galaxies with circular velocity larger than V |
12(V/10km/s)-1 |
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| Hierarchical models predict DM satellites per halo of comparable circular velocity | 320(V/10km/s)-3.75 |
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We have a problem. Amplitude of perturbations should be drastically reduced on 108 Msun scale . But be careful not to kill All satellites. Also do not reduce power on scales responsible for 50km/s satellites - there is just enough of those. |
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We know who they are: HVCs. (Kinematics, metallicity), but nobody really knows what are HVCs |
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They are dark matter lumps. Ionization and SF feedback keeps them from becoming galaxies if they collapse too later (after z=5) Bullock, Kravtsov & Weinberg (2000) |
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Klypin et al (2001)
Distances to central galaxies
Median distance of dwarf galaxies in the Local Group:
| Outer Distance Limit | Circular Velocity limit Vcirc>20km/s | Vcirc>15km/s | Vcirc>10km/s |
| 200 kpc/h | 43±20 kpc/h (8) | 57±16 kpc/h (14) | 70±13 kpc/h (24) |
| 500 kpc/h | 70±43 kpc/h (10) | 70±30 kpc/h (17) | 82±27 kpc/h (28) |
Warm Dark Matter:
Two halos with Vc=258km/s and 246km/s (Colin et al 99): reduce numbers by 20%
| Outer Distance Limit | Circular Velocity limit Vcirc>20km/s |
| 200 kpc/h | 139 kpc/h (13) |
| 500 kpc/h | 217 kpc/h (31) |
LCDM: all satellites for two halos with Vc= 200km/s
| Outer Distance Limit | Circular Velocity limit Vcirc>20km/s |
| 200 kpc/h | 118 kpc/h (50) |
| 500 kpc/h | 178 kpc/h (84) |
LCDM: Zform>10 Mvir> 2e+8Msun
| Outer Distance Limit | Circular Velocity limit Vcirc>20km/s |
| 200 kpc/h | 109 kpc/h (12) |
| 500 kpc/h | 145 kpc/h (21) |
 | Predicted Distances are more than twice and more than 3 sigma larger than for real satellites |
| Modified Dark Matter models either do not help (WDM) or make it much worse (self-interacting or annihilating DM) |
| There was a process, which increased chances of DM halo to become a dwarf satellite if the halo was close to the central galaxy |
| Candidates: tidal interaction with the "parent", higher gas pressure, patchy reionization (voids first) |
