8-12 juin, 2014


Detection of the missing baryons

Yin-Zhe Ma (University of British Columbia)

Ludovic Van Waerbeke, Gary Hinshaw, Alireza Hojjati and Douglas Scott, University of British Columbia

Previous studies of galaxy formation have shown that only 10 per cent of the baryons are in compact objects, while 90 per cent of them are missing. Numerical simulation shows that the missing baryons are in a state of diffuse plasma with temperature 10^5 to 10^7 Kevlin, which is hard to be detected by X-ray observations. In this talk, we present a halo model description of thermal Sunyaev-Zeldovich–-Lensing cross-correlation, and constrain the diffuse baryon component with the cross-correlation data obtained from the Canada France Hawaii Lensing Survey (CFHTLenS) and Planck’s thermal Sunyaev Zeldovich maps. We find that the isothermal beta-model for the gas pressure profile is consistent with the cross-correlation amplitude and shape, with the 1 and 2 halo terms detected at 3.96$\sigma$ and 3.67$\sigma$ confidence level (CL) respectively. The effective virial temperature of the isothermal gas is found to be in the range 7 *10^{5}--3*10^{8} K, and nearly half of the diffuse baryons seem to lie beyond the Virial radius. Our halo model description and the tSZ-Lensing correlation data sets clearly confirm the detection of diffuse baryons as a warm phase of intergalactic medium
(doit être confirmé par le SOC)