Planck intermediate results: XXXVII. Evidence of unbound gas from the kinetic Sunyaev-Zeldovich effect

By looking at the kinetic Sunyaev-Zeldovich effect (kSZ) in Planck nominal mission data, we present a significant detection of baryons participating in large-scale bulk flows around central galaxies (CGs) at redshift z approximate to 0.1. We estimate the pairwise momentum of the kSZ temperature fluctuations at the positions of the Central Galaxy Catalogue (CGC) samples extracted from Sloan Digital Sky Survey (SDSS-DR7) data. For the foreground-cleaned SEVEM, SMICA, NILC, and COMMANDER maps, we find 1.8-2.5 sigma detections of the kSZ signal, which are consistent with the kSZ evidence found in individual Planck raw frequency maps, although lower than found in the WMAP-9yr W-band (3.3 sigma). We further reconstruct the peculiar velocity field from the CG density field, and compute for the first time the cross-correlation function between kSZ temperature fluctuations and estimates of CG radial peculiar velocities. This correlation function yields a 3.0-3.7 sigma detection of the peculiar motion of extended gas on Mpc scales in flows correlated up to distances of 80-100 h(-1) Mpc. Both the pairwise momentum estimates and the kSZ temperature-velocity field correlation find evidence for kSZ signatures out to apertures of 8 arcmin and beyond, corresponding to a physical radius of >1 Mpc, more than twice the mean virial radius of halos. This is consistent with the predictions from hydrodynamical simulations that most of the baryons are outside the virialized halos. We fit a simple model, in which the temperature-velocity cross-correlation is proportional to the signal seen in a semi-analytic model built upon N-body simulations, and interpret the proportionality constant as an effective optical depth to Thomson scattering. We find tau(T) = (1.4 +/- 0.5) x 10(-4); the simplest interpretation of this measurement is that much of the gas is in a diffuse phase, which contributes little signal to X-ray or thermal Sunyaev-Zeldovich observations.

Keywords

cosmic background radiation, cosmology: observations, large-scale structure of Universe, galaxies: clusters: intracluster medium, PARTICLE HYDRODYNAMICS SIMULATIONS, BULK FLOW, DENSITY FIELDS, COSMOLOGICAL IMPLICATIONS, WIENER RECONSTRUCTION, PECULIAR VELOCITIES, REDSHIFT SURVEYS, GALAXY SAMPLES, IRAS-GALAXIES, DARK ENERGY

DOI

10.1051/0004-6361/201526328

Citation

Ade, P A R, Aghanim, N, Arnaud, M, Ashdown, M, Aubourg, E, Aumont, J, Baccigalupi, C, Banday, A J, Barreiro, R B, Bartolo, N, Battaner, E, Benabed, K, Benoit-Levy, A, Bersanelli, M, Bielewicz, P, Bock, J J, Bonaldi, A, Bonavera, L, Bond, J R, Borrill, J, Bouchet, F R, Burigana, C, Calabrese, E, Cardoso, J -F, Catalano, A, Chamballu, A, Chiang, H C, Christensen, P R, Clements, D L, Colombo, L P L, Combet, C, Crill, B P, Curto, A, Cuttaia, F, Danese, L, Davies, R D, Davis, R J, de Bernardis, P, de Zotti, G, Delabrouille, J, Dickinson, C, Diego, J M, Dolag, K, Donzelli, S, Doré, O, Douspis, M, Ducout, A, Dupac, X, Leon-Tavares, J, Savelainen, M & Planck Collaboration 2016, ' Planck intermediate results : XXXVII. Evidence of unbound gas from the kinetic Sunyaev-Zeldovich effect ', Astronomy and Astrophysics, vol. 586, 140 . https://doi.org/10.1051/0004-6361/201526328

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-201609163911

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[article-cris] Sähkötekniikan korkeakoulu / ELEC

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