Making maps of cosmic microwave background polarization for B-mode studies: the POLARBEAR example
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Analysis of cosmic microwave background (CMB) datasets typically requires some filtering of the raw time-ordered data. For instance, in the
context of ground-based observations, filtering is frequently used to minimize the impact of low frequency noise, atmospheric contributions and/or
scan synchronous signals on the resulting maps. In this work we have explicitly constructed a general filtering operator, which can unambiguously
remove any set of unwanted modes in the data, and then amend the map-making procedure in order to incorporate and correct for it. We show
that such an approach is mathematically equivalent to the solution of a problem in which the sky signal and unwanted modes are estimated
simultaneously and the latter are marginalized over. We investigated the conditions under which this amended map-making procedure can render
an unbiased estimate of the sky signal in realistic circumstances. We then discuss the potential implications of these observations on the choice of
map-making and power spectrum estimation approaches in the context of B-mode polarization studies. Specifically, we have studied the effects of
time-domain filtering on the noise correlation structure in the map domain, as well as impact it may have on the performance of the popular pseudospectrum
estimators. We conclude that although maps produced by the proposed estimators arguably provide the most faithful representation of
the sky possible given the data, they may not straightforwardly lead to the best constraints on the power spectra of the underlying sky signal and
special care may need to be taken to ensure this is the case. By contrast, simplified map-makers which do not explicitly correct for time-domain
filtering, but leave it to subsequent steps in the data analysis, may perform equally well and be easier and faster to implement. We focused on
polarization-sensitive measurements targeting the B-mode component of the CMB signal and apply the proposed methods to realistic simulations
based on characteristics of an actual CMB polarization experiment, POLARBEAR. Our analysis and conclusions are however more generally
applicable.
context of ground-based observations, filtering is frequently used to minimize the impact of low frequency noise, atmospheric contributions and/or
scan synchronous signals on the resulting maps. In this work we have explicitly constructed a general filtering operator, which can unambiguously
remove any set of unwanted modes in the data, and then amend the map-making procedure in order to incorporate and correct for it. We show
that such an approach is mathematically equivalent to the solution of a problem in which the sky signal and unwanted modes are estimated
simultaneously and the latter are marginalized over. We investigated the conditions under which this amended map-making procedure can render
an unbiased estimate of the sky signal in realistic circumstances. We then discuss the potential implications of these observations on the choice of
map-making and power spectrum estimation approaches in the context of B-mode polarization studies. Specifically, we have studied the effects of
time-domain filtering on the noise correlation structure in the map domain, as well as impact it may have on the performance of the popular pseudospectrum
estimators. We conclude that although maps produced by the proposed estimators arguably provide the most faithful representation of
the sky possible given the data, they may not straightforwardly lead to the best constraints on the power spectra of the underlying sky signal and
special care may need to be taken to ensure this is the case. By contrast, simplified map-makers which do not explicitly correct for time-domain
filtering, but leave it to subsequent steps in the data analysis, may perform equally well and be easier and faster to implement. We focused on
polarization-sensitive measurements targeting the B-mode component of the CMB signal and apply the proposed methods to realistic simulations
based on characteristics of an actual CMB polarization experiment, POLARBEAR. Our analysis and conclusions are however more generally
applicable.
Date Issued
2017-04-01
Date Acceptance
2016-12-18
Citation
Astronomy and Astrophysics, 2017, 600
ISSN
0004-6361
Publisher
EDP Sciences
Journal / Book Title
Astronomy and Astrophysics
Volume
600
Copyright Statement
© 2017 ESO
Sponsor
Science and Technology Facilities Council
Science and Technology Facilities Council (STFC)
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000400754000059&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
ST-N000838
ST/N000838/1
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
cosmic background radiation
cosmology: observations
DESTRIPING TECHNIQUE
STATISTICAL-ANALYSIS
MAKING ALGORITHM
POWER SPECTRUM
DATA SETS
PLANCK
FIELD
Publication Status
Published
Article Number
A60
Date Publish Online
2017-03-30