Kauffmann, White, Guidordoni 1994

Klypin et al 1999

Moore et al. 1999

 

groupgreen.gif (40362 bytes)  Satellites of "Local Group": 1.5Mpc/h sphere Z=0 LGe.gif (52177 bytes)

Z150.gif (193850 bytes) Z=10 Forming galaxy                   P150.gif (150134 bytes) Z=5 Forming galaxy

 

 

 

Sat400b.gif (8274 bytes) Statistics of satellites: Klypin et al. 1999  LGVeloc.gif (10631 bytes)

 MooreSatellite.gif (11303 bytes) 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

 

 

Hierarchical models predict DM satellites per halo of comparable circular velocity

 320(V/10km/s)-3.75

 

 

 

 

 

    

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.

              

     

We know who they are: HVCs. (Kinematics, metallicity), but nobody really knows what are HVCs

   

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)

 

 

LGVeloc.gif (10631 bytes) 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 4320 kpc/h   (8) 5716 kpc/h   (14) 7013 kpc/h   (24)
500 kpc/h 7043 kpc/h  (10) 7030 kpc/h   (17) 8227 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)

 

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