Update on QUaD

Sarah ChurchQUaD Collaboration

Funded: National Science Foundation Astronomy Program and Office of Polar Programs

Stanford University• Sarah Church (US PI)• Melanie Bowden (now industry)• James Hinderks (now Goddard) • Ben Rusholme (now IPAC)• Keith Thompson• Ed Wu

Cardiff University• Walter Gear (UK PI) • Peter Ade• Sujata Gupta• Simon Melhuish (now Manchester)• Lucio Piccirillo (now Manchester)• Nutan Rajguru (now industry)• Angiola Orlando (now Caltech)• Abigail Turner• Mike Zemcov (now Caltech)

Collège de France• Ken Ganga

U. of Chicago• Clem Pryke (Data Analysis Lead)• John Carlstrom• Tom Culverhouse• Robert Friedman• Erik Leitch (JPL)• Robert Schwarz (over winterer)

N.U.I Maynooth• Anthony Murphy• Gary Cahill• Creidhe O’Sullivan

U. of Edinburgh• Andy Taylor• Michael Brown (now Cambridge)• Patricia Castro (now Lisbon)• Yasin Memari

Caltech / JPL• Jamie Bock• John Kovac• Andrew Lange

The QUaD CassegrainTelescope

2.6m primary

Secondary supported with foam cone

Re-imaging lenses

“Deck” rotation axis

The QUaD Focal Plane

metal-mesh resonant grid filters define the band

JFETs at 4K

Focal plane at 250 mK

Load resistors

Corrugated feed

Bolometers

Vespel legs isolate the stages

440 mK plate

4K plate

QUaD Summary

Freq(GHz)

Beam(arcmin

)

No.feeds

FractionalBandwidt

h

NEQ per pair (K s1/2)

1005.1

(5.6)12 (9) 0.28 480

1503.7

(4.5)19

(17)0.27 440

Stokes Sampling

Azimuth scan

Rotation of the entire telescope

Difference 2 PSBs to get Q or U, depending on orientation

Rotate telescope and instrument about the optic axis (allowed rotation is +/-60 degrees) to change the orientation of instrumental polarization with respect to sky.

Scan in azimuth, reacquire source, rescan.

Very redundant observing strategy

Beams

No accessible planets Measured from several

sources HII regions (RCW38)

o Extended structure Quasar

o Dim and variable

5.1’ (100 GHz) 3.7’ (150 GHz) ~ 10% uncertainty

Polarization Calibration

Chopped thermal source with pol grid

Cross PolarCo Polar

Gain Calibration Relative Calibration

El nods: Frequent nods in elevation provides large correlated signal across all channels.

Cal source: Flip mirror inserts rotating polarized source into beam.

Row cals: Raster all pixels across RCW38.

Skydips, loadcurves Absolute Calibration

Temperature: Correlate full-season T-maps against BOOMERANG

Polarization: Use T calibration corrected by measured

Slightly processed data

Picture credit: Pryke

QUaD is a good polarimeterQUaD maps of Cen A

QUaD map of the Moon

Polarization levels in these maps are 1-2%

150 GHz temperature map

150 GHz temperature map

150 GHz Stokes U map

100 Degree Sidelobe ~ 1% of total power in

a narrow circular sidelobe at 100 deg. to the boresight

Source of contamination from the ground and the moon

Lead/Trail field differencing removes ground pickup

Data cuts remove moon contamination

Field differencing is used to mitigate ground pickup

Picture credit: PrykePicture credit: Pryke

150 GHz Field-differences Stokes U map

Smoothed maps show polarization

Picture credit: Wu

Smoothed maps show polarization

Picture credit: Wu

Data analysis methodPower Spectrum Determination

Monte-Carlo based analysis Noise only simulations, based on measured noise

correlation properties, used to correct noise bias in the power spectrum

Signal-only simulations, based on WMAP best fit parameters, are used to estimate the effects of sky cut and filtering

The scatter in the power spectrum from multiple simulations corrected as above gives the error bars on the band powers

Season 1 100GHz/150GHz Cross-correlationQUaD first year power spectra

One pipeline uses full spherical harmonic analysis using HEALPIX, other uses flat sky approx. and 2D FFTs

Season 1 100GHz/150GHz Cross-correlationQUaD first year power spectra

67 days mapping 60 square degrees of sky Only ~30% of final data set Submitted paper at arXiv:0705.2359 (Feb

10th ApJ) Bandpowers are publicly available

Observing Strategy Allows for Many Jack-knife Tests

Observing Strategy Allows for Many Jack-knife Tests

Power spectra are consistent with -CDM

QUaD cosmological parameter estimates Using the polarization data only

Using priors:0.0<h <1 <0.80.0<As<2.50<ns<2

Preview of next data release

Other science from 3rd season data

Measurements of galactic dust – spectral index and polarization

Map above shows 2 days of QUaD observations from season 3

Summary

QUaD first data published and power spectra are publicly available

Three observing seasons are complete Next data release probably ~ mid-late April Also work taking place on

High-ell T spectrum Polarized galactic emission Foreground limits