The SunyaevZel'dovich effect and the value of {OMEGA}_0_.
Abstract
We consider the SunyaevZel'dovich (SZ) effect as a probe of {OMEGA}_0_: Using a selfconsistent modeling of Xray clusters, we examine the dependence of both the mean Compton y parameter and the SZ source counts on {OMEGA}_0_. These quantities increase with decreasing {OMEGA}_0_ due to the earlier epoch of structure formation in lowdensity cosmogonies; the results depend only on the quantity of gas heated to the virial temperature of collapsed objects and are independent of the spatial distribution of the gas in the potential wells. Specifically, we compare two models which reproduce the presentday abundance of clusters  a biased, critical universe and an unbiased, open model with {OMEGA}_0_=0.3. We find that the mean y parameter approaches the current FIRAS limit of y<2.5x10^5^ for the open model, demonstrating the importance of improving this limit on spectral distortions, and that the SZ source counts and corresponding redshift distribution differ significantly between the two cosmogonies; millimeter surveys covering a large area should thus provide interesting constraints on the density parameter of the Universe and on the evolution of the heated gas fraction in virialized objects.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 October 1996
 arXiv:
 arXiv:astroph/9511084
 Bibcode:
 1996A&A...314...13B
 Keywords:

 COSMOLOGY: THEORY;
 COSMIC MICROWAVE BACKGROUND;
 Astrophysics
 EPrint:
 uuencoded, compressed tar file including tex file, AA style file, and 2 postscript figures. Submitted to Astronomy and Astrophysics