Particle Astrophysics & Cosmology SS 2008 1

Chapter 8Structure Formation

Particle Astrophysics & Cosmology SS 2008 2

Galaxy distribution

Particle Astrophysics & Cosmology SS 2008 3

Galaxy distribution

Simulated and observed galaxy distributions: which is which?

Particle Astrophysics & Cosmology SS 2008 4

Galaxy distribution

… the answer

Particle Astrophysics & Cosmology SS 2008 5

Numerical CDM simulations

Simulated large-scale structure for different cosmologies

Particle Astrophysics & Cosmology SS 2008 6

Numerical CDM simulations

The Millennium simulation

Particle Astrophysics & Cosmology SS 2008 7

Numerical CDM simulations

Computational efforts …

Particle Astrophysics & Cosmology SS 2008 8

Numerical CDM simulations

cluster

large galaxy

Movies

Particle Astrophysics & Cosmology SS 2008 9

Simulations and observations

Power spectrum of galaxy distribution is accurately reproduced by simulations

Particle Astrophysics & Cosmology SS 2008 10

Simulations and observations

hot dark matter is out!

Particle Astrophysics & Cosmology SS 2008 11

Problems with CDM

Tully-Fischer relation is offset

Particle Astrophysics & Cosmology SS 2008 12

Problems with CDM

galaxy

cluster

Milky Way possesses too few satellite halos

(“missing satellites”)works for Virgo Cluster

Particle Astrophysics & Cosmology SS 2008 13

Problems with CDM

galaxy

cluster

Rotation curve of a dwarf galaxy:NFW profile ovepredicts central densities of DM in galaxies (‘cusp problem’)

dashed: NFW halo

yellow: stars

red: gas

magenta: Burkert halo

blue: total

Particle Astrophysics & Cosmology SS 2008 14

Web sites for numerical simulations

http://www.mpa-garching.mpg.de/~volker/gadget/index.htmlhttp://www.mpa-garching.mpg.de/galform/millenniumhttp://www.virgo.dur.ac.uk/new/index.phphttp://www.aip.de/People/MSteinmetz/Movies.html