Improved Constraints on Cosmology and Foregrounds from BICEP2 and Keck Array Cosmic Microwave Background Data with Inclusion of 95 GHz Band
Abstract
We present results from an analysis of all data taken by the BICEP2 and Keck Array cosmic microwave background (CMB) polarization experiments up to and including the 2014 observing season. This includes the first Keck Array observations at 95 GHz. The maps reach a depth of 50 nK deg in Stokes Q and U in the 150 GHz band and 127 nK deg in the 95 GHz band. We take auto and crossspectra between these maps and publicly available maps from WMAP and Planck at frequencies from 23 to 353 GHz. An excess over lensed Λ CDM is detected at modest significance in the 95 ×150 B B spectrum, and is consistent with the dust contribution expected from our previous work. No significant evidence for synchrotron emission is found in spectra such as 23 ×95 , or for correlation between the dust and synchrotron sky patterns in spectra such as 23 ×353 . We take the likelihood of all the spectra for a multicomponent model including lensed Λ CDM , dust, synchrotron, and a possible contribution from inflationary gravitational waves (as parametrized by the tensortoscalar ratio r ) using priors on the frequency spectral behaviors of dust and synchrotron emission from previous analyses of WMAP and Planck data in other regions of the sky. This analysis yields an upper limit r_{0.05}<0.09 at 95% confidence, which is robust to variations explored in analysis and priors. Combining these B mode results with the (more modeldependent) constraints from Planck analysis of CMB temperature plus baryon acoustic oscillations and other data yields a combined limit r_{0.05}<0.07 at 95% confidence. These are the strongest constraints to date on inflationary gravitational waves.
 Publication:

Physical Review Letters
 Pub Date:
 January 2016
 DOI:
 10.1103/PhysRevLett.116.031302
 arXiv:
 arXiv:1510.09217
 Bibcode:
 2016PhRvL.116c1302B
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 17 pages, 18 figures, minor updates to reflect accepted version, data and figures available for download at http://bicepkeck.org/