Baryon content of massive galaxy clusters at 0.57 < z < 1.33

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Authors: Chiu, I., Mohr, J., McDonald, M., Bocquet, S., Ashby, M. 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., Suhada, R., Strazzullo, V., Zenteno, A.
• Format: Text
• Language: English
• Published: Oxford University Press 2015
• Subjects: Article; Pivot; South Pole; South pole
• Online Access: http://mnras.oxfordjournals.org/cgi/content/short/455/1/258; 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 M 500 = 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 <f>$M_{\star }^{\mathrm{BCG}}$</f> constitutes 0.12 ± 0.01 per cent of the halo mass for a 6 × 1014 M ⊙ cluster, and this fraction falls as <f>$M_{500}^{-0.58\pm 0.07}$</f>. The cluster stellar mass function has a characteristic mass M 0 = 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 f ICM , the collapsed baryon fraction f c and the baryon fraction f b . At a pivot mass of 6 × 1014 M ⊙ and redshift z = 0.9, the characteristic values are f ⋆ = 1.1 ± 0.1 per cent, f ICM = 9.6 ± 0.5 per cent, f c = 10.7 ± 1.1 per cent and f b = 10.7 ± 0.6 per cent. These fractions all vary with cluster mass at high significance, with higher mass clusters having lower f ⋆ and f c and higher f ICM and f b . 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 f ICM ) and the field (lower f ⋆ , higher f ICM ), balancing to keep f ⋆ and f ICM approximately constant since z ∼ 0.9.