Planck intermediate results. XLVII. Planck constraints on reionization history
Abstract
We investigate constraints on cosmic reionization extracted from the Planck cosmic microwave background (CMB) data. We combine the Planck CMB anisotropy data in temperature with the low-multipole polarization data to fit LCDM models with various parameterizations of the reionization history. We obtain a Thomson optical depth tau=0.058 +/- 0.012 for the commonly adopted instantaneous reionization model. This confirms, with only data from CMB anisotropies, the low value suggested by combining Planck 2015 results with other data sets and also reduces the uncertainties. We reconstruct the history of the ionization fraction using either a symmetric or an asymmetric model for the transition between the neutral and ionized phases. To determine better constraints on the duration of the reionization process, we also make use of measurements of the amplitude of the kinetic Sunyaev-Zeldovich (kSZ) effect using additional information from the high resolution Atacama Cosmology Telescope and South Pole Telescope experiments. The average redshift at which reionization occurs is found to lie between z=7.8 and 8.8, depending on the model of reionization adopted. Using kSZ constraints and a redshift-symmetric reionization model, we find an upper limit to the width of the reionization period of Dz < 2.8. In all cases, we find that the Universe is ionized at less than the 10% level at redshifts above z~10. This suggests that an early onset of reionization is strongly disfavoured by the Planck data. We show that this result also reduces the tension between CMB-based analyses and constraints from other astrophysical sources.
Keywords
Cite
@article{arxiv.1605.03507,
title = {Planck intermediate results. XLVII. Planck constraints on reionization history},
author = {Planck Collaboration and R. Adam and N. Aghanim and M. Ashdown and J. Aumont and C. Baccigalupi and M. Ballardini and A. J. Banday and R. B. Barreiro and N. Bartolo and S. Basak and R. Battye and K. Benabed and J. -P. Bernard and M. Bersanelli and P. Bielewicz and J. J. Bock and A. Bonaldi and L. Bonavera and J. R. Bond and J. Borrill and F. R. Bouchet and M. Bucher and C. Burigana and E. Calabrese and J. -F. Cardoso and J. Carron and H. C. Chiang and L. P. L. Colombo and C. Combet and B. Comis and A. Coulais and B. P. Crill and A. Curto and F. Cuttaia and R. J. Davis and P. de Bernardis and A. de Rosa and G. de Zotti and J. Delabrouille and E. Di Valentino and C. Dickinson and J. M. Diego and O. Doré and M. Douspis and A. Ducout and X. Dupac and F. Elsner and T. A. Enßlin and H. K. Eriksen and E. Falgarone and Y. Fantaye and F. Finelli and F. Forastieri and M. Frailis and A. A. Fraisse and E. Franceschi and A. Frolov and S. Galeotta and S. Galli and K. Ganga and R. T. Génova-Santos and M. Gerbino and T. Ghosh and J. González-Nuevo and K. M. Górski and A. Gruppuso and J. E. Gudmundsson and F. K. Hansen and G. Helou and S. Henrot-Versillé and D. Herranz and E. Hivon and Z. Huang and S. Ili_ and A. H. Jaffe and W. C. Jones and E. Keihänen and R. Keskitalo and T. S. Kisner and L. Knox and N. Krachmalnicoff and M. Kunz and H. Kurki-Suonio and G. Lagache and A. Lähteenmäki and J. -M. Lamarre and M. Langer and A. Lasenby and M. Lattanzi and C. R. Lawrence and M. Le Jeune and F. Levrier and A. Lewis and M. Liguori and P. B. Lilje and M. López-Caniego and Y. -Z. Ma and J. F. Macías-Pérez and G. Maggio and A. Mangilli and M. Maris and P. G. Martin and E. Martínez-González and S. Matarrese and N. Mauri and J. D. McEwen and P. R. Meinhold and A. Melchiorri and A. Mennella and M. Migliaccio and M. -A. Miville-Deschênes and D. Molinari and A. Moneti and L. Montier and G. Morgante and A. Moss and P. Naselsky and P. Natoli and C. A. Oxborrow and L. Pagano and D. Paoletti and B. Partridge and G. Patanchon and L. Patrizii and O. Perdereau and L. Perotto and V. Pettorino and F. Piacentini and S. Plaszczynski and L. Polastri and G. Polenta and J. -L. Puget and J. P. Rachen and B. Racine and M. Reinecke and M. Remazeilles and A. Renzi and G. Rocha and M. Rossetti and G. Roudier and J. A. Rubiño-Martín and B. Ruiz-Granados and L. Salvati and M. Sandri and M. Savelainen and D. Scott and G. Sirri and R. Sunyaev and A. -S. Suur-Uski and J. A. Tauber and M. Tenti and L. Toffolatti and M. Tomasi and M. Tristram and T. Trombetti and J. Valiviita and F. Van Tent and P. Vielva and F. Villa and N. Vittorio and B. D. Wandelt and I. K. Wehus and M. White and A. Zacchei and A. Zonca},
journal= {arXiv preprint arXiv:1605.03507},
year = {2016}
}
Comments
19 pages, 18 figures. accepted in A&A