Benchmark parameters for CMB polarization experiments

Abstract

The recently detected polarization of the cosmic microwave background (CMB) holds the potential for revealing the physics of inflation and gravitationally mapping the large-scale structure of the universe, if so called B-mode signals below 10 −7 , or tenths of a µK, can be reliably detected. We provide a language for describing systematic effects which distort the observed CMB temperature and polarization fields and so contaminate the B-modes. We identify 7 types of effects, described by 11 distortion fields, and show their association with known instrumental systematics such as common mode and differential gain fluctuations, line cross-coupling, pointing errors, and differential polarized beam effects. Because of aliasing from the small-scale structure in the CMB, even uncorrelated fluctuations in these effects can affect the large-scale B modes relevant to gravitational waves. Many of these problems are greatly reduced by having an instrumental beam that resolves the primary anisotropies (FWHM ≪ 10 ′ ). To reach the ultimate goal of an inflationary energy scale of 3 × 10 15 GeV, polarization distortion fluctuations must be controlled at the 10 −2 − 10 −3 level and temperature leakage to the 10 −4 − 10 −3 level depending on effect. For example pointing errors must be controlled to 1.5 ′′ rms for arcminute scale beams or a percent of the Gaussian beam width for larger beams; low spatial frequency differential gain fluctuations or line cross-coupling must be eliminated at the level of 10 −4 rms.

Likelihood methods for cluster dark energy surveys

“…This fact allows a measure of "self-calibration" of the selection function p iµ (M ) through the relationships between b iµ andm iµ in a given pixel [4,5]. Note that the selection function can include effects such as instrument noise and point source contamination as well as the observable-mass relation itself.…”

“…The wealth of information contained in even the cluster counts alone partially offsets the fundamental problem that the masses of the clusters are not directly observable. Techniques that utilize this information to relate cluster observables such as Sunyaev-Zel'dovich (SZ) flux, X-ray temperature and surface brightness, or optical richness and shear to cluster masses and hence the cosmology are known in the literature as "self-calibration" methods [3,4,5].…”

Planck2015 results

“…Instead of the Cartesian grid 40 on each side used previously, the beam maps were produced on both a Cartesian grid of 200 on each side and 2 resolution, and a polar grid with a radius of 100 and a resolution of 2 in radius and 30 in azimuth. Hu et al 2003;Leahy et al 2010). In the likelihood pipeline (Planck Collaboration XI 2016), this additive leakage is modelled as a polynomial whose parameters are fitted to the power spectra.…”

Antenna-coupled TES bolometers for the SPIDER experiment

“…For a B-mode detection at T/S=0.01, the requirements for beams are very stringent. 24 However, if the polarization differences can be made with the same beam, these problems can be avoided. This idealized polarization rotation is most closely approximated by a rotating half-wave plate at the pupil of the optics.…”

“…1/f noise lower than 0.1 Hz is routinely achieved in various bolometric CMB experiments. Therefore, the performance in the second function of a polarization modulator, i.e., its ability to reduce polarization artifacts from the instrument, most notably the beam mismatch, passband mismatch, and gain mismatch, 1,24 is what should be weighted more in evaluating different modulation schemes.…”