COSMIC MICROWAVE BACKGROUND CONSTRAINTS ON THE DURATION AND TIMING OF REIONIZATION FROM THE SOUTH POLE TELESCOPE
- Berkeley Center for Cosmological Physics, Department of Physics, University of California, and Lawrence Berkeley National Labs, Berkeley, CA 94720 (United States)
- Department of Physics, University of California, Berkeley, CA 94720 (United States)
- Department of Physics, Yale University, P.O. Box 208210, New Haven, CT 06520-8120 (United States)
- Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States)
- University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
- Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
- NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO 80305 (United States)
- Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada)
- California Institute of Technology, MS 249-17, 1216 East California Boulevard, Pasadena, CA 91125 (United States)
The epoch of reionization is a milestone of cosmological structure formation, marking the birth of the first objects massive enough to yield large numbers of ionizing photons. However, the mechanism and timescale of reionization remain largely unknown. Measurements of the cosmic microwave background (CMB) Doppler effect from ionizing bubbles embedded in large-scale velocity streams-known as the patchy kinetic Sunyaev-Zel'dovich (kSZ) effect-can be used to constrain the duration of reionization. When combined with large-scale CMB polarization measurements, the evolution of the ionized fraction, x-bar{sub e}, can be inferred. Using new multi-frequency data from the South Pole Telescope (SPT), we show that the ionized fraction evolved relatively rapidly. For our basic foreground model, we find the kSZ power sourced by reionization at l = 3000 to be D{sup patchy}{sub 3000} {<=} 2.1 {mu}K{sup 2} at 95% confidence. Using reionization simulations, we translate this to a limit on the duration of reionization of {Delta}z{identical_to}z{sub x}-bar{sub e=0.20}-z{sub x}-bar{sub e=0.99}{<=}4.4 (95% confidence). We find that this constraint depends on assumptions about the angular correlation between the thermal SZ power and the cosmic infrared background (CIB). Introducing the degree of correlation as a free parameter, we find that the limit on kSZ power weakens to D{sup patchy}{sub 3000} {<=} 4.9 {mu}K{sup 2}, implying {Delta}z {<=} 7.9 (95% confidence). We combine the SPT constraint on the duration of reionization with the Wilkinson Microwave Anisotropy Probe measurement of the integrated optical depth to probe the cosmic ionization history. We find that reionization ended with 95% confidence at z > 7.2 under the assumption of no tSZ-CIB correlation, and z > 5.8 when correlations are allowed. Improved constraints from the full SPT data set in conjunction with upcoming Herschel and Planck data should detect extended reionization at >95% confidence provided {Delta}z {>=} 2. These CMB observations complement other observational probes of the epoch of reionization such as the redshifted 21 cm line and narrowband surveys for Ly{alpha}-emitting galaxies.
- OSTI ID:
- 22092452
- Journal Information:
- Astrophysical Journal, Vol. 756, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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