Kavli Affiliate: Sarah Church

| First 5 Authors: Sarah Church, Lloyd Knox, Martin White, ,

| Summary:

Multi-frequency measurements of the microwave sky can be decomposed into maps

of distinct physical components such as the cosmic microwave background (CMB)

and the Sunyaev-Zel’dovich (SZ) effect. Each of the multi–frequency

measurements is a convolution of the spectrum on the sky with the bandpass of

the instrument. Here we analytically calculate the contamination of the

component maps that can result from errors in our knowledge of the bandpass

shape. We find, for example, that for Planck an unknown 10% ramp across each

band results in a CMB map dT = dT_{CMB} – 4.3e-3 dT_{SZ} plus the usual

statistical noise. The variance of this contaminant is more than a factor of

100 below the noise variance at all angular scales and even further below the

CMB signal variance. This contamination might lead to an error in the velocity

of rich clusters inferred from the kinetic SZ effect, however the error is

negligible, O(50 km/s), if the bandpass is known to 10%. Bandpass errors might

be important for future missions measuring the CMB-SZ correlation.

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