Seeing the Invisible: Observing the Dark Side of the Universe

Sarah BridleUniversity College London

What we see

What we don’t see

What we don’t see

Missing matter: Dark Matter(matter that doesn’t shine)

What we don’t seeMissing energy: Dark Energy(energy that is not matter)

Missing matter: Dark Matter(matter that doesn’t shine)

Supernovae as Standard Candles

Big Bang 5 billion years ago Today

Why is the Universe Accelerating?

• Einstein’s cosmological constant

• A new fluid called Dark Energy

• General Relativity is wrong

Seeing the Invisible:Is there something in between us and

the wall and tree?

Using the bending of light to see the invisible

Just one Equation from General Relativity

90 years ago

Eddington confirmed Einstein’s prediction during a solar eclipse

Average galaxies together to measure weak gravitational shear

Simulated Dark Matter Map

Gravitational Lensing Map

Universe was 0.2 Gyr old

Universe was 1 Gyr old

Universe was 4.7 Gyrs old

Today (13.6 Gyr)

Map in 3d

Map in 3d

Typical star used for finding telescope response

Typical galaxyused for lensing

Gravitational Lensing

Atmosphere and Telescope

Pixelisation

Noise

www.great08challenge.info

Results from the HST COSMOS Survey

The Largest ever Survey with HST

The Visible The Invisible

In 3 Dimensions

The Future

JDEM

Future prospects

• Cosmic microwave background radiation– Distribution of dark matter at early times

• Distribution of galaxies – Some clues to distribution of matter

• Galaxy velocities– Galaxies fall towards dark matter clumps

• Gravitational lensing

The Dark Energy Survey

The camera: DECam

Hexapod

Corrector Lenses

CCDReadout

Filters Shutter

Mechanical Interface of DECam Project to the Blanco

Focal plane (detector)

Ground vs Space

weak lensing shear

space

ground

HST COSMOS

Why is the Universe Accelerating?

• Einstein’s cosmological constant

• A new fluid called Dark Energy

• General Relativity is wrong