The QUaD Galactic Plane Survey 1: Maps And Analysis of Diffuse Emission
  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 degrees in galactic longitude l, and -4<b<+4 degrees in
galactic latitude b. At 0.02 degree 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
2.35+/-0.01 (stat) +/- 0.02 (sys) for |b|<1 degree, 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 degree) yields
mean spectral indices of -0.32 +/- 0.03 and 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 150GHz. We find agreement in
polarization fraction between QUaD 100 GHz and WMAP W band, the latter giving
1.1 +/- 0.4 %.
