Detection of warm and diffuse baryons in large scale structure from the cross-correlation of gravitational lensing and the thermal Sunyaev-Zeldovich effect

摘要

We report the first detection of a correlation between gravitational lensingby large scale structure and the thermal Sunyaev-Zeldovich (tSZ) effect. Usingthe mass map from the Canada France Hawaii Telescope Lensing Survey (CFHTLenS)and a newly-constructed tSZ map from Planck, we measure a non-zero correlationbetween the two maps out to one degree angular separation on the sky, with anoverall significance of 6 sigma. The tSZ maps are formed in a manner thatremoves primary cosmic microwave background fluctuations and minimizes residualcontamination by galactic and extragalactic dust emission, and by CO lineemission. We perform numerous tests to show that our measurement is immune tothese residual contaminants. The resulting correlation function is consistentwith the existence of a warm baryonic gas tracing the large scale structurewith a bias b_gas. Given the shape of the lensing kernel, our signalsensitivity peaks at a redshift z~0.4, where half a degree separation on thesky corresponds to a physical scale of ~10 Mpc. The amplitude of the signalconstrains the product (b_gas/1)(T_e / 0.1 keV)(n_e / 1 m^-3)=2.01\pm 0.31\pm0.21, at redshift zero. Our study suggests that a substantial fraction of the"missing" baryons in the universe may reside in a low density warm plasma thattraces dark matter.