Publication Date:
2013-10-12
Description:
We present a first measurement of the stellar mass component of galaxy clusters selected via the Sunyaev–Zel'dovich (SZ) effect, using 3.6 and 4.5 μm photometry from the Spitzer Space Telescope . Our sample consists of 14 clusters detected by the Atacama Cosmology Telescope (ACT), which span the redshift range 0.27 〈 z 〈 1.07 (median z = 0.50) and have dynamical mass measurements, accurate to about 30 per cent, with median M 500 = 6.9 10 14 M . We measure the 3.6 and 4.5 μm galaxy luminosity functions, finding the characteristic magnitude ( m *) and faint-end slope (α) to be similar to those for infrared-selected cluster samples. We perform the first measurements of the scaling of SZ observables ( Y 500 and y 0 ) with both brightest cluster galaxy (BCG) stellar mass and total cluster stellar mass ( $M_{500}^{\rm star}$ ). We find a significant correlation between BCG stellar mass and Y 500 ( $E(z)^{-2/3}\,D_A^2\,Y_{500} \propto M_*^{1.2 \pm 0.6}$ ), although we are not able to obtain a strong constraint on the slope of the relation due to the small sample size. Additionally, we obtain $E(z)^{-2/3}\,D_A^2\,Y_{500} \propto M_{500}^{\rm star}\,^{1.0 \pm 0.6}$ for the scaling with total stellar mass. The mass fraction in stars spans the range 0.006–0.034, with the second ranked cluster in terms of dynamical mass (ACT-CL J0237–4939) having an unusually low total stellar mass and the lowest stellar mass fraction. For the five clusters with gas mass measurements available in the literature, we see no evidence for a shortfall of baryons relative to the cosmic mean value.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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