Measuring the Three‐dimensional Structure of Galaxy Clusters. I. Application to a Sample of 25 Clusters

We discuss a method to constrain the intrinsic three-dimensionale shapes ofgalaxy clusters by combining X-Ray and Sunyaev-Zeldovich observations. Themethod is applied to a sample of 25 X-Ray selected clusters, with measuredSunyaev-Zeldovich temperature decrements. The sample turns out to be slightlybiased, with strongly elongated clusters preferentially aligned along the lineof sight. This result demonstrates that X-Ray selected cluster samples may beaffected by morphological and orientation effects even if a relatively highthreshold signal-to-noise ratio is used to select the sample. A large majorityof the clusters in our sample exhibit a marked triaxial structure, withprolate-like shapes being slightly more likely than oblate-like ones; thespherical hypothesis is strongly rejected for most sample members. Cooling flowclusters do not show preferentially regular morphologies.Comment: 13 pages, 9 figures. Accepted by Ap