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

  • Author(s): Ade, PAR
  • Aghanim, N
  • Arnaud, M
  • Ashdown, M
  • Aubourg, E
  • Aumont, J
  • Baccigalupi, C
  • Banday, AJ
  • Barreiro, RB
  • Bartolo, N
  • Battaner, E
  • Benabed, K
  • Benoit-Lévy, A
  • Bersanelli, M
  • Bielewicz, P
  • Bock, JJ
  • Bonaldi, A
  • Bonavera, L
  • Bond, JR
  • Borrill, J
  • Bouchet, FR
  • Burigana, C
  • Calabrese, E
  • Cardoso, JF
  • Catalano, A
  • Chamballu, A
  • Chiang, HC
  • Christensen, PR
  • Clements, DL
  • Colombo, LPL
  • Combet, C
  • Crill, BP
  • Curto, A
  • Cuttaia, F
  • Danese, L
  • Davies, RD
  • Davis, RJ
  • De Bernardis, P
  • De Zotti, G
  • Delabrouille, J
  • Dickinson, C
  • Diego, JM
  • Dolag, K
  • Donzelli, S
  • Doré, O
  • Douspis, M
  • Ducout, A
  • Dupac, X
  • Efstathiou, G
  • Elsner, F
  • Enßlin, TA
  • Eriksen, HK
  • Finelli, F
  • Forni, O
  • Frailis, M
  • Fraisse, AA
  • Franceschi, E
  • Frejsel, A
  • Galeotta, S
  • Galli, S
  • Ganga, K
  • Génova-Santos, RT
  • Giard, M
  • Gjerløw, E
  • González-Nuevo, J
  • Górski, KM
  • Gregorio, A
  • Gruppuso, A
  • Hansen, FK
  • Harrison, DL
  • Henrot-Versillé, S
  • Hernández-Monteagudo, C
  • Herranz, D
  • Hildebrandt, SR
  • Hivon, E
  • Hobson, M
  • Hornstrup, A
  • Huffenberger, KM
  • Hurier, G
  • Jaffe, AH
  • Jaffe, TR
  • Jones, WC
  • Juvela, M
  • Keihänen, E
  • Keskitalo, R
  • Kitaura, F
  • Kneissl, R
  • Knoche, J
  • Kunz, M
  • Kurki-Suonio, H
  • Lagache, G
  • Lamarre, JM
  • Lasenby, A
  • Lattanzi, M
  • Lawrence, CR
  • Leonardi, R
  • León-Tavares, J
  • Levrier, F
  • Liguori, M
  • Lilje, PB
  • et al.
Abstract

© ESO, 2016. 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 ≈ 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 1.8-2.5σ 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 (3.3σ). 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 3.0-3.7σ 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 τT = (1.4 ± 0.5) × 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.

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