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Simulating Interferometers for the CMB Sky

Simulating Interferometers for the CMB Sky. Eric Lopez UC Berkeley With Peter Timbie and the Observational Cosmology Group, UW Madison. Outline of Talk. CMB 101 What is a Power Spectrum? Polarization and B-modes The EPIC mission The Basics of Interferometers My Simulation Method

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Simulating Interferometers for the CMB Sky

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  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 Special Thanks to: Peter Timbie SiddarthMalu The Observational Cosmology Group, UW Madison JPL, NASA, and CALTECH for use of HEALPIX and CMBFAST Images provided by: Peter Timbie http://en.wikipedia.org http://antwrp.gsfc.nasa.gov/apod/astropix.html http://lambda.gsfc.nasa.gov/cmbfast/ MMVII

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