Evidence for Line‐of‐Sight Structure in a Comparison of X‐Ray and Optical Observations of the High‐Redshift Cluster RCS 043938‐2904.7

Benjamin Cain, David G. Gilbank, M. W. Bautz, A. Hicks, H. K. C. Yee, M. Gladders, E. Ellingson, L. F. Barrientos, G. P. Garmire
2008 Astrophysical Journal  
We present new Chandra observations of a high redshift (z~1) galaxy cluster discovered in the Red-Sequence Cluster Survey (RCS): RCS043938-2904.7. X-ray luminosity measurements and mass estimates are consistent with L_X-T_X and M_delta-T_X relationships obtained from low-redshift data. Assuming a single cluster, X-ray mass estimates are a factor of ~10-100 below the red-sequence optical richness mass estimate. Optical spectroscopy reveals that this cluster comprises two components which are
more » ... e enough to perhaps be physically associated. We present simple modeling of this two-component system which then yields an X-ray mass and optical richness consistent with expectations from statistical samples of lower redshift clusters. An unexpectedly high gas mass fraction is measured assuming a single cluster, which independently supports this interpretation. Additional observations will be necessary to confirm the excess gas mass fraction and to constrain the mass distribution.
doi:10.1086/586694 fatcat:zxa2gr5rwjhktluv2gaypnyjgi