报告题目：Detection of the missing baryons with Planck maps

报 告 人：Yinzhe Ma，U.Manchester

报告时间：2014年12月19日10:00

报告地点：物理系三楼报告厅

报告摘要：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. We will present two studies that coherently detect the missing baryons. The first is the cross-correlation between the kinetic Sunyaev-Zeldovich maps from Planck with the linear reconstructed velocity field. We find significance (4.6 sigma) detection of the peculiar motion of gas on Mpc scales. Further studies show that this bulk motion indicates that the concentration of gas constitutes a fraction of f_b=0.8, which indicates that all baryons are detected with the Planck kSZ maps. Second, we cross-correlate the thermal Sunyaev- Zeldovich from Planck maps with gravitational lensing from the Canada France Hawaii Lensing Survey (CFHTLenS) and constrain the diffuse baryon component with the various pressure profile. We find that 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. In addition, by stacking the pairs of luminous red galaxies, we can place a constraint on the temperature of the filament in between the dark matter halos. The study shows that baryons are no longer missing, with the cross-correlation between CMB SZ maps with gravitational lensing or cluster distribution.