QUaD: A CMB Polarization Experiment… First Year Results, arXiv:0705.2359v1
Robert B. FriedmanThe University of Chicago
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What I Will Attempt to Cover
CMB Pol.What is QUaD?Analysis Techniques.First Year Results (arXiv:0705.2359v1) & Future
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CMB Polarization Science
Curves are WMAP3 EE Polarization alone
cannot compete with TT for parameters (save for ) It’s a paradigm check
BB is the hot stuff!!! Likely below the reach of
current experiments (QUaD) Probes inflation &
foregrounds through lensing
QUaD will nail these
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Who is QUaD? Chicago
Clem Pryke, Tom Culverhouse, myself, John Carlstrom, Erik Leitch (JPL), Robert Schwartz (SP)
Caltech John Kovac, Ken Ganga (Paris), Andre Lange, Jamie Bock
Stanford Sarah Church, Ed Wu, Jamie Hendricks, Ben Rusholme,
Melanie Bowden, Keith Thompson Cardiff
Walter Gear, Mike Zemcov, Nutan Rajguru, Angiola Orland, Peter Ade, Simon Melhuish, Lucio Piccirillo
Edinburgh Andy Taylor, Michael Brown, Patricia Castro (Lisbon)
Maynooth Anthony Murphy, Creidhe O’Sullivan, Gary Cahill
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What is QUaD? QUaD stands for QUEST at DASI
QUEST is the bolometer array receiver
DASI interferometer first detected polariztion
High Resolution sensitive to modes up to l~2500
Receiver focal plane consists of 31
Polarization Sensitive Bolometer pairs 19 at 150GHz and 12 at 100GHz.
2.6m Cassegrain focus assembly
mounted on the DASI platform tri-axial orientation; AZ, EL, DK
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The Foam Cone
Typical radio telescopes use metallic secondary support legs Can induce spurious polarization
Foam Cone made from mm-wave transparent Zotefoam. Axially symmetric rigid cone structure adds stability
ME
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Map Making Time Ordered Data (TOD) is “field differenced” first Cancels common ground signal
3rd order polynomial removed from raw TOD Cuts down “1/f noise” (mostly atmosphere ie. large scale variations like clouds).
PSB pair TOD summed and differenced Sum produces Intensity or T signal Difference used for stokes Q & U
Inverse variance weighting applied to summations Variance map simultaneously constructed
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QUaD E and B Maps
Top Row: E & B Polarization Signal No BB signal expected!
Bottom Row: “Deck” Jackknife … should look like noise.
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Spectra Estimation Procedure
Generate random CMB realizations, observe with simulated telescope Signal only, noise only and signal
plus noise sim TOD for sum/diff Include all known parameters and
uncertainties (ie. beam shapes, polarization efficiencies, etc.)
Construct maps from sim TOD and calculate sim spectra from them
Use sims to correct observed power spectra and estimate error bars Subtract noise power measured from
noise only sim spectra Estimate filter/beam suppression
measured as the ratio of signal only sim spectra vs. input spectra
variance per band in signal plus noise spectra is the ~error
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Jackknife Spectra
Jackknife tests Difference maps from independent data setsFrequency, Deck Angle, Scan Direction, Focal Plane and Season
Should be consistent w/
ZERO!
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The Future of QUaD
Preliminary 1st Season Analysis Represents 67 of ~200 days already in the can.See results paper @ arXiv:0705.2359v1
3rd Season observations currently underway.Will likely provide at least another ~70 more days
Coming Soon… Reduced errorbars (more time)New and improved beam modelsBetter control of systematics
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