| Abstract: | Our velocity relative to the rest frame of the cosmic microwave background
(CMB) generates a dipole temperature anisotropy on the sky which has been well
measured for more than 30 years, and has an accepted amplitude of v/c =
0.00123, or v = 369km/s. In addition to this signal generated by Doppler
boosting of the CMB monopole, our motion also modulates and aberrates the CMB
temperature fluctuations (as well as every other source of radiation at
cosmological distances). This is an order 0.1% effect applied to fluctuations
which are already one part in roughly one hundred thousand, so it is quite
small. Nevertheless, it becomes detectable with the all-sky coverage, high
angular resolution, and low noise levels of the Planck satellite. Here we
report a first measurement of this velocity signature using the aberration and
modulation effects on the CMB temperature anisotropies, finding a component in
the known dipole direction, (l,b)=(264, 48) [deg], of 384km/s +- 78km/s (stat.)
+- 115km/s (syst.). This is a significant confirmation of the expected
velocity. |
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