1.*
Institute of Astronomy, Madingley Road, University of
Cambridge, Cambridge CB3 OHA, England
*

2.*
Department of Astrophysical Sciences, Princeton University,
Princeton, NJ 08544, USA
*

3.*
Canadian Institute of Theoretical Astrophysics, University of
Toronto, 60 St. George St., Toronto, Canada
*

Abstract

The hot gas in the IGM produces anisotropies in the Cosmic Microwave
Background (CMB) through the thermal Sunyaev-Zel'dovich (SZ)
effect. The SZ effect is a powerful probe of large-scale structure in
the universe, and must be carefully subtracted from measurements of
the primary CMB anisotropies. We use moving-mesh hydrodynamical
simulations to study the 3-dimensional statistics of the gas, and
compute the mean comptonization parameter y and the angular power
spectrum of the SZ fluctuations, for different cosmologies. We compare
these results with predictions using the Press-Schechter formalism.
We find that the two methods agree approximately, but differ in
details. We discuss this discrepancy, and show that resolution limits
the reliability of our results to the 200 < l < 2000 range.
For cluster normalized CDM models, we find a mean
y-parameter of the order of 10^{-6}, one order of magnitude below
the current observational limits from the COBE/FIRAS instrument. For
these models, the SZ power spectrum is comparable to the primordial
power spectrum around l=2000. It is well below the projected noise
for the upcoming MAP satellite, and should thus not be a limitation
for this mission. It should be easily detectable with the future
Planck Surveyor mission. We show that groups and filaments (kT
< 5 keV contribute about 50% of the SZ power spectrum at
l=500. About half of the SZ power spectrum on these scales are
produced at redshifts z < 0.1, and can thus be detected and
removed using existing catalogs of galaxies and X-ray clusters.

Please Contact Me !!

Mail: komatsu@astr.tohoku.ac.jp