Supplement to Lecture XI: Structure Formation (Numerical ...

SupplementtoLectureXI:StructureFormation(NumericalResults)

1

2

a

π/k[comovingscale]

1kpc 10kpc 100kpc 1Mpc 10Mpc 100Mpc 1Gpc 10Gpc

1

0.1

10−2

10−3

10−4

10−5

10−6

10−7

recombination

matter-radiationequality

• Nocausalcommunicationpossible• Relativisticanalysisnecessary

• DMperturbationsgrowlogarithmically• Acousticoscillationsinbaryon-photonplasma

IGMreheating• Baryonssmoothlydistributed

• BaryonandDMperturbationsgrow~G(a)

matter-Λequality

• DMswitchestogrowthδ~a

Nonlineartransition,Δ~1

Scalesofinterest

Transferfunction:results

0.001

0.01

0.1

1

0.001 0.01 0.1 1

CDM

all

3

k(Mpc−1)

T(k)

Eisenstein&Hu(1998)formulae

MajorTechniques

1.  Higher-orderperturbationtheory–  Usefulforweaklynonlinearevolution,e.g.largescale

structureat~10Mpcscales–  Butwillneverunderstandgalaxyformationbydoingthis!

2.  N-bodysimulations–  “Exact”solutionofDM-onlyevolutionevenwhenδ>>1–  Understandformation/structureofgalaxyhaloes,merger

history,…

3.  Analytictreatmentsofhaloformation–  Usefulforgainingintuition–  ButnotasaccurateasfullN-bodyapproaches

4

5

SimulatedDarkMatterDistribution(15Mpc/hthickslice)MilleniumSimulation,Springeletal2005

z=18.3

6

SimulatedDarkMatterDistribution(15Mpc/hthickslice)MilleniumSimulation,Springeletal2005

z=5.7

7

SimulatedDarkMatterDistribution(15Mpc/hthickslice)MilleniumSimulation,Springeletal2005

z=1.4

8

SimulatedDarkMatterDistribution(15Mpc/hthickslice)MilleniumSimulation,Springeletal2005

z=0.0

NonlinearPowerSpectrum

9

MilleniumSimulationSpringeletal2005Gray=lineartheory