Chiu, I., Mohr, J., McDonald, M., Bocquet, S., Ashby, Matthew L. N., Bayliss, M., Benson, B. A., Bleem, L. E., Brodwin, M., Desai, S., Dietrich, J. P., Forman, W. R., Gangkofner, C., Gonzalez, A. H., Hennig, C., Liu, J., Reichardt, C. L., Saro, A., Stalder, B., Stanford, S. A., Song, J., Schrabback, T., Šuhada, R., Strazzullo, V., and Zenteno, A. 2016. "Baryon content of massive galaxy clusters at 0.57 < z < 1.33." Monthly Notices of the Royal Astronomical Society, 455 258–275. https://doi.org/10.1093/mnras/stv2303.
We study the stellar, brightest cluster galaxy (BCG) and intracluster medium (ICM) masses of 14 South Pole Telescope (SPT) selected galaxy clusters with median redshift z = 0.9 and mass M500 = 6 × 1014 M?. We estimate stellar masses for each cluster and BCG using six photometric bands, the ICM mass using X-ray observations and the virial masses using the SPT Sunyaev-Zel'dovich effect signature. At z = 0.9, the BCG mass M_{star }^{BCG} constitutes 0.12 ± 0.01 per cent of the halo mass for a 6 × 1014 M? cluster, and this fraction falls as M_{500}^{-0.58± 0.07}. The cluster stellar mass function has a characteristic mass M0 = 1011.0 ± 0.1 M?, and the number of galaxies per unit mass in clusters is larger than in the field by a factor of 1.65 ± 0.20. We combine our SPT sample with previously published samples at low redshift and correct to a common initial mass function and for systematic virial mass differences. We then explore mass and redshift trends in the stellar fraction f?, the ICM fraction fICM, the collapsed baryon fraction fc and the baryon fraction fb. At a pivot mass of 6 × 1014 M? and redshift z = 0.9, the characteristic values are f? = 1.1 ± 0.1 per cent, fICM = 9.6 ± 0.5 per cent, fc = 10.7 ± 1.1 per cent and fb = 10.7 ± 0.6 per cent. These fractions all vary with cluster mass at high significance, with higher mass clusters having lower f? and fc and higher fICM and fb. When accounting for a 15 per cent systematic virial mass uncertainty, there is no statistically significant redshift trend at fixed mass. Our results support the scenario where clusters grow through accretion from subclusters (higher f?, lower fICM) and the field (lower f?, higher fICM), balancing to keep f? and fICM approximately constant since z ˜ 0.9.
