BICEP2 / Keck Array IX: New bounds on anisotropies of CMB polarization rotation and implications for axionlike particles and primordial magnetic fields

(Keck Array and BICEP2 Collaborations)

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Abstract

We present the strongest constraints to date on anisotropies of cosmic microwave background (CMB) polarization rotation derived from 150 GHz data taken by the BICEP2 & Keck Array CMB experiments up to and including the 2014 observing season (BK14). The definition of the polarization angle in BK14 maps has gone through self-calibration in which the overall angle is adjusted to minimize the observed TB and EB power spectra. After this procedure, the QU maps lose sensitivity to a uniform polarization rotation but are still sensitive to anisotropies of polarization rotation. This analysis places constraints on the anisotropies of polarization rotation, which could be generated by CMB photons interacting with axionlike pseudoscalar fields or Faraday rotation induced by primordial magnetic fields. The sensitivity of BK14 maps (∼3 μK-arc min) makes it possible to reconstruct anisotropies of the polarization rotation angle and measure their angular power spectrum much more precisely than previous attempts. Our data are found to be consistent with no polarization rotation anisotropies, improving the upper bound on the amplitude of the rotation angle spectrum by roughly an order of magnitude compared to the previous best constraints. Our results lead to an order of magnitude better constraint on the coupling constant of the Chern-Simons electromagnetic term gaγ≤7.2×10-2/HI (95% confidence) than the constraint derived from the B-mode spectrum, where HI is the inflationary Hubble scale. This constraint leads to a limit on the decay constant of 10-6fa/Mpl at mass range of 10-33≤ma≤10-28 eV for r=0.01, assuming gaγ∼α/(2πfa) with α denoting the fine structure constant. The upper bound on the amplitude of the primordial magnetic fields is 30 nG (95% confidence) from the polarization rotation anisotropies.

Original languageEnglish (US)
Article number102003
JournalPhysical Review D
Volume96
Issue number10
DOIs
StatePublished - 2017

Bibliographical note

Funding Information:
The Keck Array project has been made possible through support from the National Science Foundation under Grants No. ANT-1145172 (Harvard), No. ANT-1145143 (Minnesota), and& No. ANT-1145248 (Stanford) and from the Keck Foundation (Caltech). The development of antenna-coupled detector technology was supported by the JPL Research and Technology Development Fund and Grants No. 06-ARPA206-0040 and No. 10-SAT10-0017 from the NASA APRA and SAT programs. The development and testing of focal planes were supported by the Gordon and Betty Moore Foundation at Caltech. Readout electronics were supported by a Canada Foundation for Innovation grant to UBC. The computations in this paper were run on the Odyssey cluster supported by the FAS Science Division Research Computing Grou p at Harvard University. The analysis effort at Stanford and SLAC is partially supported by the U.S. Department of Energy Office of Science. We thank the staff of the U.S. Antarctic Program and in particular the South Pole Station, without whose help this research would not have been possible. Most special thanks go to our heroic winter-overs Robert Schwarz and Steffen Richter. We thank all those who have contributed past efforts to the BICEP /Keck Array series of experiments, including the BICEP1 team. We thank Chang Feng for providing the histogram data shown in Ref. .

Funding Information:
The Keck Array project has been made possible through support from the National Science Foundation under Grants No. ANT-1145172 (Harvard), No. ANT-1145143 (Minnesota), and& No. ANT-1145248 (Stanford) and from the Keck Foundation (Caltech). The development of antenna-coupled detector technology was supported by the JPL Research and Technology Development Fund and Grants No. 06-ARPA206-0040 and No. 10-SAT10-0017 from the NASA APRA and SAT programs. The development and testing of focal planes were supported by the Gordon and Betty Moore Foundation at Caltech. Readout electronics were supported by a Canada Foundation for Innovation grant to UBC. The computations in this paper were run on the Odyssey cluster supported by the FAS Science Division Research Computing Grou p at Harvard University. The analysis effort at Stanford and SLAC is partially supported by the U.S. Department of Energy Office of Science. We thank the staff of the U.S. Antarctic Program and in particular the South Pole Station, without whose help this research would not have been possible. Most special thanks go to our heroic winter-overs Robert Schwarz and Steffen Richter. We thank all those who have contributed past efforts to the BICEP/Keck Array series of experiments, including the BICEP1 team.

Publisher Copyright:
© 2017 American Physical Society.

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