Stéphane Courteau

ΛCDM Structure Formation Models
Small scales, big problems?
• Scaling relations normalization
– Cannot simultaneously predict LF and TF zero-points
• Central regions too dense
– Predicted dark matter halos have more mass near center
(too cuspy) than allowed by observed rotation curves
• Angular momentum crisis
– Disk galaxies are too small for given rotation speed
– Predicted distribution of specific angular momentum
different from observed
• Too much substructure
– Galaxy size dark matter halos have hundreds of sub-halos,
but Milky Way has only ~10 satellites
• Backwards Colour-Luminosity relation
– Lack of very luminous galaxies
– Colour-magnitude relation of spiral galaxies (Bell et al 2003)