Effects of Preheated Clusters on the CMB Spectrum

Abstract

Mounting evidence from $x$-ray observations reveals that bound objects should receive some form of energy in the past injected from non-gravitaional sources. We report that an instantaneous heating scheme, for which gases in dense regions were subjected to a temperature jump of 1keV at $z=2$ whereas those in rarified regions remained intact, can produce bound objects obeying the observed mass-temperature and luminosity-temperature relations. Such preheating lowers the peak Sunyaev-Zeldovich (SZ) power by a factor of 2 and exacerbates the need for the normalization of matter fluctuations $σ_8$ to assume an extreme high value $(\sim 1.1)$ for the SZ signals to account for the excess anisotropy on 5-arcminute scale detected by the Cosmic Background Imager in the cosmic microwave background radiation.

6 pages, 3 figs, submitted to ApJL. Corrected for a normalization problem and one more simulation result is included. Conclusion has been reversed. Motion pictures of simulations can be found at http://asweb.phys.ntu.edu.tw/~tseng/MEMO/SZE.html