Pauline GagnonPhysicist and communicator at CERN

The dark side of the Universe

Shrimp Nebula© VLT, European Space Observatory

• Convince you all of the existence of dark matter

• Review how one can catch dark matter

Plan

fi

©2000, 2001 B Katzung, Andromeda galaxy

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dark matter 27%

dark energy 68%

visible matter 5%

Universe content

© NASA, Orion nebula

Dark energy:

Discovered in 1998 while studying the relative speeds of galaxies

The Universe expansion is accelerating

A completely unknown type of energy must be causing this expansion

Physics Nobel Prize in 2011 went to Saul Perlmutter, Brian Schmidt and Adam Riess

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dark matter 27%

dark energy 68%

visible matter 5%

✓

Universe content

What is generating the gravitational pull needed to maintain these

galaxies together?

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Dark matter provides the gravitational force needed to maintain these galaxies together

Mais comment mesure-t-on la composition de l’Univers?

1 second

Protons and neutrons form

380 000 years

Atoms form

1 billion years

Stars and galaxies form

13.7 billion years

2.7 degrees

1032 degrees

The Big Bang

Stars and Dust Across Corona Australis © Ignacio Diaz Bobillo

Rayonnement fossile

The Universe became transparent 380 000 years after the Big Bang

The photons present then are still moving around freely

But the Universe expanded and they cooled down

We still observe them today in the form of microwave background at 2.725 degrees Kelvin

Cosmological microwave background

Width and temperature of each lump(or angular spectrum measured by Planck)

Angular width of all structures observed in the Universe

Tem

para

ture

fluc

tuati

ons

in (μ

•K)

Big Bang Standard Model

Λ-CDM model: a model with 6 free parameters including

Ωd : dark matter densityΩΛ : dark energy density

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Dark energy68%

Dark matter27%

Matter5%

Ωd

Ωd

ΩΛ

How did the Universe evolve

from an immense fog of free particles…

…to an Universe filled with stars and galaxies?