Planck CollaborationAde, P. A. R.P. A. R.AdeAghanim, N.N.AghanimNatoli, PaoloPaoloNatoliPolenta, GianlucaGianlucaPolenta2020-09-172020-09-172016-02-01https://hdl.handle.net/20.500.13025/4496Astronomy & Astrophysics, Volume 586, id.A140, <NUMPAGES>14</NUMPAGES> pp.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 &ap; 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 1.8-2.5sigma detections of the kSZ signal, which are consistent with the kSZ evidence found in individualPlanck raw frequency maps, although lower than found in the WMAP-9yr W-band (3.3sigma). 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 3.0-3.7sigma detection of the peculiar motion of extended gas on Mpc scales in flows correlated up to distances of 80-100 h<SUP>-1</SUP> 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<SUB>T</SUB> = (1.4 0.5) 10<SUP>-4</SUP>; 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.cosmic background radiationcosmology observationslarge-scale structure of Universegalaxies clusters intracluster medium10.1051/0004-6361/201526328http://adsabs.harvard.edu/abs/2016A&A...586A.140P2016A&A...586A.140P