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Searching for Anisotropic Cosmic Birefringence with Polarization Data from SPTpol

  • Bianchini, F.
  • Wu, W. L. K.
  • Ade, P. A. R.
  • Anderson, A. J.
  • Austermann, J. E.
  • Avva, J. S.
  • Balkenhol, L.
  • Baxter, E.
  • Beall, J. A.
  • Bender, A. N.
  • Benson, B. A.
  • Bleem, L. E.
  • Carlstrom, J. E.
  • Chang, C. L.
  • Chaubal, P.
  • Chiang, H. C.
  • Chou, T. L.
  • Citron, R.
  • Moran, C. Corbett
  • Crawford, T. M.
  • And 52 more
Published Article
Publication Date
Oct 04, 2020
Submission Date
Jun 14, 2020
DOI: 10.1103/PhysRevD.102.083504
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We present a search for anisotropic cosmic birefringence in 500 deg$^2$ of southern sky observed at 150 GHz with the SPTpol camera on the South Pole Telescope. We reconstruct a map of cosmic polarization rotation anisotropies using higher-order correlations between the observed cosmic microwave background (CMB) $E$ and $B$ fields. We then measure the angular power spectrum of this map, which is found to be consistent with zero. The non-detection is translated into an upper limit on the amplitude of the scale-invariant cosmic rotation power spectrum, $L(L+1)C_L^{\alpha\alpha}/2\pi < 0.10 \times 10^{-4}$ rad$^2$ (0.033 deg$^2$, 95% C.L.). This upper limit can be used to place constraints on the strength of primordial magnetic fields, $B_{1 \rm Mpc} < 17 {\rm nG} $ (95% C.L.), and on the coupling constant of the Chern-Simons electromagnetic term $g_{a\gamma} < 4.0 \times 10^{-2}/H_I $ (95% C.L.), where $H_I$ is the inflationary Hubble scale. For the first time, we also cross-correlate the CMB temperature fluctuations with the reconstructed rotation angle map, a signal expected to be non-vanishing in certain theoretical scenarios, and find no detectable signal. We perform a suite of systematics and consistency checks and find no evidence for contamination.

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