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Published October 1, 2015 | Published + Submitted
Journal Article Open

The Q/U Imaging Experiment: Polarization Measurements of the Galactic Plane at 43 and 95 GHz


We present polarization observations of two Galactic plane fields centered on Galactic coordinates (l, b) = (0°, 0°) and (329°, 0°) at both Q (43 GHz) and W bands (95 GHz), covering between 301 and 539 square degrees depending on frequency and field. These measurements were made with the QUIET instrument between 2008 October and 2010 December, and include a total of 1263 hr of observations. The resulting maps represent the deepest large-area Galactic polarization observations published to date at the relevant frequencies with instrumental rms noise varying between 1.8 and 2.8 μK deg, 2.3–6 times deeper than corresponding WMAP and Planck maps. The angular resolution is 27!3 and 12!8 FWHM at Q and W bands, respectively. We find excellent agreement between the QUIET and WMAP maps over the entire fields, and no compelling evidence for significant residual instrumental systematic errors in either experiment, whereas the Planck 44 GHz map deviates from these in a manner consistent with reported systematic uncertainties for this channel. We combine QUIET and WMAP data to compute inverse-variance-weighted average maps, effectively retaining small angular scales from QUIET and large angular scales from WMAP. From these combined maps, we derive constraints on several important astrophysical quantities, including a robust detection of polarized synchrotron spectral index steepening of ≈0.2 off the plane, as well as the Faraday rotation measure toward the Galactic center (RM = −4000 ± 200 rad m^(−2)), all of which are consistent with previously published results. Both the raw QUIET and the co-added QUIET+WMAP maps are made publicly available together with all necessary ancillary information.

Additional Information

© 2015. The American Astronomical Society. Received 2015 June 19; accepted 2015 July 31; published 2015 September 24. Bruce Winstein, who led the QUIET project, died in 2011, soon after observations concluded. The project's success owes a great debt to his intellectual and scientific leadership. Support for the QUIET instrument and operation comes through the NSF cooperative agreement AST-0506648. Support was also provided by NSF awards PHY-0355328, AST-0448909, AST-1010016, and PHY-0551142; KAKENHI 20244041, 20740158, and 21111002; PRODEX C90284; a KIPAC Enterprise grant; and by the Strategic Alliance for the Implementation of New Technologies (SAINT). This work was performed on the Abel cluster, owned and maintained by the University of Oslo and NOTUR (the Norwegian High Performance Computing Consortium). Portions of this work were performed at the Jet Propulsion Laboratory (JPL) and California Institute of Technology, operating under a contract with the National Aeronautics and Space Administration. The Q-band polarimeter modules were developed using funding from the JPL R & TD program. H.K.E. acknowledges an ERC Starting Grant under FP7. C.D. and M.V. acknowledge support from an ERC Starting Grant (no. 307209). C.D. also acknowledges support from the STFC (U.K.). J.Z. gratefully acknowledges a South Africa National Research Foundation Square Kilometre Array Research Fellowship. L.B. acknowledges support from CONICYT Grant PFB-06. A.D.M. acknowledges a Sloan Fellowship. PWV measurements were provided by the Atacama Pathfinder Experiment (APEX). We thank CONICYT for granting permission to operate within the Chajnantor Scientific Preserve in Chile, and ALMA for providing site infrastructure support. Field operations were based at the Don Esteban facility run by Astro-Norte. We are particularly indebted to the engineers and technician who maintained and operated the telescope: José Cortés, Cristobal Jara, Freddy Muñoz, and Carlos Verdugo. In addition, we acknowledge the following people for their assistance in the instrument design, construction, commissioning, operation, and data analysis: Augusto Gutierrez Aitken, Colin Baines, Phil Bannister, Hannah Barker, Matthew R. Becker, Alex Blein, Mircea Bogdan, Alison Brizius, Ricardo Bustos, April Campbell, Anushya Chandra, Sea moon Cho, Sarah Church, Joelle Cooperrider, Mike Crofts, Emma Curry, Maire Daly, Fritz Dejongh, Joy Didier, Greg Dooley, Hans Eide, Pedro Ferreira, Jonathon Goh, Will Grainger, Peter Hamlington, Takeo Higuchi, Seth Hillbrand, Christian Holler, Ben Hooberman, Kathryn D. Huff, William Imbriale, Koji Ishidoshiro, Norm Jarosik, Pekka Kangaslahti, Dan Kapner, Oliver King, Eiichiro Komatsu, Jostein Kristiansen, Donna Kubik, Richard Lai, David Leibovitch, Kelly Lepo, Siqi Li, Martha Malin, Jorge May, Mark McCulloch, Jeff McMahon, Steve Meyer, Oliver Montes, David Moore, Makoto Nagai, Hogan Nguyen, Glen Nixon, Ian O'Dwyer, Gustavo Orellana, Stephen Osborne, Heather Owen, Stephen Padin, Felipe Pedreros, Ashley Perko, Joey Richards, Alan Robinson, Jacklyn Sanders, Dale Sanford, Yunior Savon, Kendrick Smith, Mary Soria, Alex Sugarbaker, David Sutton, Keith Vanderlinde, Liza Volkova, Ross Williamson, Edward Wollack, Stephanie Xenos, Octavio Zapata, Mark Zaskowski, and Joe Zuntz. Some of the results in this paper have been derived using the HEALPix package.

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Published - Ruud_2015p89.pdf

Submitted - 1508.02778v1.pdf


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