Observational limits on patchy reionization: Implications for B modes
The recent detection of secondary CMB anisotropy by the South Pole Telescope limits temperature fluctuations from the optical depth-modulated Doppler effect to T_3000 < √13μK at multipoles ℓ ∼ 3000. This bound is the first empirical constraint on optical depth fluctuations at arcminute scales, τ_...
| Published in: | Physical Review D |
|---|---|
| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
American Physical Society
2010
|
| Subjects: | |
| Online Access: | http://hdl.handle.net/1811/48057 https://doi.org/10.1103/PhysRevD.81.067302 |
| Summary: | The recent detection of secondary CMB anisotropy by the South Pole Telescope limits temperature fluctuations from the optical depth-modulated Doppler effect to T_3000 < √13μK at multipoles ℓ ∼ 3000. This bound is the first empirical constraint on optical depth fluctuations at arcminute scales, τ_3000=0.001T_3000/μK, implying that these fluctuations are no more than a few percent of the mean. Modulation of the quadrupole source to polarization generates B modes that are bounded as B_3000 = 0.003T_3000. The maximal extrapolation to the ℓ ∼ 100 gravitational wave regime yields B_100 = 0.1T_3000 and remains in excess of gravitational lensing if the comoving size of ionized regions is R ≳ 80 Mpc. If patchy reionization produces much of the observed arcminute scale temperature fluctuations, current bounds on B_100 already require R ≲ 200 Mpc, and limits on both T_3000 and B_100 can be expected to improve rapidly. |
|---|