Table 3
Minimum χ2 values and statistical uncertainties (1σ) for α, derived from the D-estimators with ℓmax ≃ 1500.
| Method | α[deg] | biasa [deg] | χ2(α = 0) | Δχ2 d |
|
|
||||
| T–B | ||||
| Commander ................. | 0.44 ± 0.10 | 0.01 | 87.1 | − 20.9 |
| NILC b ................. | 0.43 ± 0.09 | − 0.01 | 104.3 | − 22.5 |
| SEVEM ................. | 0.31 ± 0.10 | 0.02 | 80.0 | − 10.3 |
| SMICA b ................. | 0.40 ± 0.08 | 0.00 | 92.7 | − 23.9 |
| SMICA × bc ................. | 0.39 ± 0.09 | − 0.01 | 92.8 | − 18.8 |
| E–B | ||||
| SMICA × bc ................. | 0.29 ± 0.05 | 0.00 | 135.9 | − 39.9 |
| Combined | ||||
| SMICA × bc ................. | 0.31 ± 0.05 | 0.00 | 228.7 | − 57.9 |
Notes. The χ2 values for α = 0 and the change Δχ2 for the corresponding value of the birefringence angle are provided in the fourth and fifth columns respectively.
The bias refers to the average value of α determined using the corresponding FFP8.1 simulations.
NILC and SMICA have smaller uncertainties compared with Commander and SEVEM, which follows from the naive expectation of the rms in the polarization maps (see Table 1 of Planck Collaboration IX 2016).
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