Computational Cosmology

Student: Mischa Knabenhans Advisor: Joachim Stadel

How did I get here?

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Elementary School

Fascination for planets & the night sky

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Gymnasium

MATURA THESIS:

The history and development of navigation techniques

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Bachelors:

SEMESTER PROJECTS:

Weak gravitational lensing

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Masters:

SEMESTER PROJECT: Higgs physics

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Master Thesis:

Higher spin black holes in (2+1)-D gravity

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PhD Research:

How does structure form in the Universe?M. Knabenhans 8

MAIN QUESTION:

What is the Universe (like)?

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What is my object of interest?

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What does the Universe look like?

Earth

~12’000 kmM. Knabenhans 11

What does the Universe look like?

~10 000 000 000 km = 1e10 km ~ 0.0003 pcM. Knabenhans 12

What does the Universe look like?

~ 3e14 km ~ 10 pcM. Knabenhans 13

What does the Universe look like?

~ 1e18 km ~ 30 kpcM. Knabenhans 14

What does the Universe look like?

~ 1 MpcM. Knabenhans 15

What does the Universe look like?

~ 30 MpcM. Knabenhans 16

V. Springel et al.

What does the Universe look like?

~ 150 MpcM. Knabenhans 17

What does the Universe look like?

J. Stadel (2017)

~ 1 Gpc ~ 1/10 of observable UniverseM. Knabenhans 18

What does the Universe look like?

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Context & main goal

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EUCLID:

Satellite

Aims at demystifying

DARK ENERGY

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BACKGROUND

Launch in Dec 2020

Maps the geometry of the dark universe out to redshift 2

ESA (sci.esa.int)

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Density fluctuations:

overdense region

underdense region

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LSS Statistics:

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rr

r

r

r

⇠(r) = h�(x)�(x+ r)i

Correlation function

�(x) =⇢(x)� ⇢̄

⇢̄

Density perturbation

Properties of the Universe:

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P (k) = FT [⇠(r)]

Power spectrum

NL Power spectrum - the observable:

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What is my PhD project about?

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TheoryOverview:

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Overview:Theory

Simulation

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Overview:Simulation

Experiment

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Overview:ExperimentSimulation

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Overview:ExperimentSimulation

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Overview:ExperimentSimulation

⌦m,⌦b,⌦⇤, ns, h, w

by comparison

MC: Standard parameter estimation:

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Computational cost:

~15’000 CPU hours

Box size: (1024 Mpc/h)^3 # Particles: 2048^3

A MC approach is infeasible!

⌦m,⌦b,⌦⇤, ns, h, w

Parameter estimation by emulation:

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Computational cost:

~1 CPU second

Box size: (1024 Mpc/h)^3 # Particles: 2048^3

Speed up: 1e6

Emulation can do it!⌦m,⌦b,⌦⇤, ns, h, w

Questions?

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