1. Simulating Interferometers for the CMB Sky
Eric Lopez
UC Berkeley
With Peter Timbie and the Observational Cosmology Group, UW Madison

2. Outline of Talk CMB 101 What is a Power Spectrum?
Polarization and B-modes
The EPIC mission
The Basics of Interferometers
My Simulation Method
Spiral Interferometer Arrays
The Results

3. The Cosmic Microwave Background
Emitted during recombination 400,000 years after Big Bang.
Temperature was 3,000 K when emitted, and has since cooled to 2.73 K
Primary Temperature Anisotropies occur at about 20 μK

4. What on Earth is a Power Spectrum?

5. Polarization and the B-Modes
Light from the CMB is partially polarized
Polarization map is split into 2 components: E-Modes (the curl-less part) and B-Modes (the divergence-less part)
B-Modes are believed to be caused by gravitational waves from inflation
E-modes occur at about 1µK, while B-Modes occur at about 100nK

6. The Einstein Polarization Interferometer for Cosmology (EPIC)

7. Basics of Interferometers
Each unique baseline corresponds to a particular angular scale on the sky
Longer baselines → smaller angular scales→ larger multipole moments
Each baseline defines a radius in the UV plane
Want as many unique baselines as possible
Max of N(N-1)/2 Baselines for N horns

8. The Simulation Process

9. The Amazing Spiral Array
30.2 cm
64 Horns , Each 2.5 cm wide,
with secondary mirror 7.5 cm wide

10. The Results First peak clearly visible Minimal power loss due to beam
Spiral array reproduces recognizable power spectrum even at 10% bandwidth
Made using spiral array configuration on a 20° by 20° map, with a 10% bandwidth, and a 15° beam.

11. The End MMVII Special Thanks to: Images provided by:
Peter Timbie
Siddarth Malu
The Observational Cosmology Group, UW Madison
JPL, NASA, and CALTECH for use of HEALPIX and CMBFAST
Images provided by:
MMVII