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Published October 20, 2010 | Published
Journal Article Open

The QUaD galactic plane survey. I. Maps and analysis of diffuse emission


We present a survey of ~800 deg^2 of the galactic plane observed with the QUaD telescope. The primary products of the survey are maps of Stokes I, Q, and U parameters at 100 and 150 GHz, with spatial resolution of 5' and 3'.5, respectively. Two regions are covered, spanning approximately 245°–295° and 315°–5° in the galactic longitude l and −4° < b < +4° in the galactic latitude b. At 0°.02 square pixel size, the median sensitivity is 74 and 107 kJy sr^(−1) at 100 GHz and 150 GHz respectively in I, and 98 and 120 kJy sr^(−1) for Q and U. In total intensity, we find an average spectral index of α = 2.35 ± 0.01 (stat) ± 0.02 (sys) for |b| ≤ 1°, indicative of emission components other than thermal dust. A comparison to published dust, synchrotron, and free–free models implies an excess of emission in the 100 GHz QUaD band, while better agreement is found at 150 GHz. A smaller excess is observed when comparing QUaD 100 GHz data to the WMAP five-year W band; in this case, the excess is likely due to the wider bandwidth of QUaD. Combining the QUaD and WMAP data, a two-component spectral fit to the inner galactic plane (|b| ≤ 1°) yields mean spectral indices of α_s = −0.32 ± 0.03 and α_d = 2.84 ± 0.03; the former is interpreted as a combination of the spectral indices of synchrotron, free–free, and dust, while the second is largely attributed to the thermal dust continuum. In the same galactic latitude range, the polarization data show a high degree of alignment perpendicular to the expected galactic magnetic field direction, and exhibit mean polarization fraction 1.38 ± 0.08 (stat) ± 0.1 (sys)% at 100 GHz and 1.70 ± 0.06 (stat) ± 0.1 (sys)% at 150 GHz. We find agreement in polarization fraction between QUaD 100 GHz and the WMAP W band, the latter giving 1.1% ± 0.4%.

Additional Information

© 2010 American Astronomical Society. Received 2009 December 16; accepted 2010 June 23; published 2010 September 27. This paper is dedicated to the memory of Andrew Lange, who gave wisdom and guidance to so many members of the astrophysics and cosmology community. His presence is sorely missed. We thank our colleagues on the BICEP experiment and Dan Marrone for useful discussions. QUaD is funded by the National Science Foundation in the USA, through grants ANT-0338138, ANT-0338335, and ANT-0338238, by the Science and Technology Facilities Council (STFC) in the UK and by the Science Foundation Ireland. The BOOMERanG collaboration kindly allowed the use of their CMB maps for our calibration purposes. M.Z. acknowledges support from a NASA Postdoctoral Fellowship. P.G.C. acknowledges funding from the Portuguese FCT. S.E.C. acknowledges support from a Stanford Terman Fellowship. J.R.H. acknowledges the support of an NSF Graduate Research Fellowship, a Stanford Graduate Fellowship, and a NASA Postdoctoral Fellowship. Y.M. acknowledges support from a SUPA Prize studentship. C.P. acknowledges partial support from the Kavli Institute for Cosmological Physics through the grant NSF PHY-0114422. E.Y.W. acknowledges receipt of an NDSEG fellowship. We acknowledge the use of the Legacy Archive for Microwave Background Data Analysis (LAMBDA). Support for LAMBDA is provided by the NASA Office of Space Science.

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October 20, 2023