Bicep2. III. INSTRUMENTAL SYSTEMATICS

Abstract

In a companion paper, we have reported a >5σ detection of degree scale B-mode polarization at 150 GHz by the BICEP2 experiment. Here we provide a detailed study of potential instrumental systematic contamination to that measurement. We focus extensively on spurious polarization that can potentially arise from beam imperfections. We present a heuristic classification of beam imperfections according to their symmetries and uniformities, and discuss how resulting contamination adds or cancels in maps that combine observations made at multiple orientations of the telescope about its boresight axis. We introduce a technique, which we call "deprojection," for filtering the leading order beam-induced contamination from time-ordered data, and show that it reduces power in BICEP2ʼs actual and null-test BB spectra consistent with predictions using high signal-to-noise beam shape measurements. We detail the simulation pipeline that we use to directly simulate instrumental systematics and the calibration data used as input to that pipeline. Finally, we present the constraints on BB contamination from individual sources of potential systematics. We find that systematics contribute BB power that is a factor of ∼10× below BICEP2ʼs three-year statistical uncertainty, and negligible compared to the observed BB signal. The contribution to the best-fit tensor/scalar ratio is at a level equivalent to r=(3-6)×10 −3 .

Quasi-matter bounce and inflation in the light of the CSL model

“…It is also instructive to mention that, if future observations confirm the results of the BICEP2 Collaboration [70], i.e. r 0.2, then the value of λ GRW would not be compatible with the values of V and N used in Table 1.…”

Reducing the tension between the BICEP2 and the Planck measurements: A complete exploration of the parameter space

“…In addition to the BICEP2 data [1], we use the Planck CMB temperature data [26], the WMAP 9 year CMB polarization data [44,45], and the BAO data from the SDSS DR9 [46], SDSS DR7 [47] and 6dF [48] in our cosmological parameter fitting. For clarity, we use the following labels to denote the different data sets:…”

“…• Planck + WP + BICEP: Beside the Planck and WMAP data sets, the BICEP2 data [1,2] is also included;…”

“…The BICEP2 experiment [1,2], a dedicated cosmic microwave background (CMB) polarization experiment, has announced recently the detection of the B-mode polarization in CMB, based on an observation of about 380 square degrees low-foreground area of sky during 2010 to 2012 in the South Pole. The detected Bmode power is in the multipole range 30 < < 150.…”

“…The running of the scalar power spectrum The BICEP2 team [1] pointed out that a simple way to relax this tension is to take the running of spectrum index into account. But with the large |α s |, it is difficult to get a sufficient e-folds number for slow roll inflation [28].…”