The QUAD Galactic Plane Survey 1: Maps and Analysis of Diffuse Emission
Culverhouse, T. and Ade, P. and Bock, J. and Bowden, M. and Brown, M.L. and Cahill, G. and Castro, P.G. and Church, S. and Friedman, R. and Ganga, K. and Gear, W.K. and Gupta, S. and Hinderks, J. and Kovac, J. and Lange, A.E. and Leach, S. and Melhuish, S.J. and Memari, Y. and Murphy, J.A. and Orlando, A. and Schwarz, R. and O'Sullivan, C. and Piccirillo, L. and Pryke, C. and Rajguru, N. and Rusholme, B. and Taylor, A.N. and Thompson, K.L. and Turner, A.H. and Wu, E.Y.S. and Zemcov, M. (2010) The QUAD Galactic Plane Survey 1: Maps and Analysis of Diffuse Emission. Astrophysical Journal, 722 (2). pp. 1057-1077. ISSN 0004-637X
We present a survey of ~ 800 square degrees of the galactic plane observed with the QUaD telescope. The primary product of the survey are maps of Stokes I, Q and U parameters at 100 and 150 GHz, with spatial resolution 5 and 3.5 arcminutes respectively. Two regions are covered, spanning approximately 245 - 295° and 315 - 5° in galactic longitude l, and -4 < b < +4° in galactic latitude b. At 0:02° square pixel size, the median sensitivity is 74 and 107 kJy/sr at 100 GHz and 150 GHz respectively in I, and 98 and 120 kJy/sr 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 WMAP 5-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 αs = -0:32+-0:03 and αd = 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 attributed largely 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 WMAP W band, the latter giving 1:1+-0:4%.
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