On cooling flows and the Sunyaev-Zeldovich effect

We study the effect of cooling flows in galaxy clusters on the Sunyaev-Zeld ovich (SZ) distortion and the possible cosmological implications. The SZ ef fect, along with X-ray observations of clusters, is used to determine the H ubble constant, H-0. Blank-sky surveys of SZ effect are being planned to co nstrain the geometry of the universe through cluster counts. It is also kno wn that a significant fraction of clusters have cooling flows in them, whic h change the pressure profile of intracluster gas. Since the SZ decrement d epends essentially on the pressure profile, it is important to study possib le changes in the determination of cosmological parameters in the presence of a cooling flow. We build several representative models of cooling flows and compare the results with the corresponding case of gas in hydrostatic e quilibrium. We find that cooling flows can lead to an overestimation of the Hubble constant. Specifically, we find that for realistic models of coolin g flow with mass deposition (varying (m)over dot with radius), there is of the order of similar to 10% deviation in the estimated value of the Hubble constant (from that for gas without a cooling flow) even after excluding si milar to 80% of the cooling-how region from the analysis. We also discuss t he implications of using cluster counts from SZ observations to constrain o ther cosmological parameters in the presence of clusters with cooling flows .