Evolution of the Blue Luminosity-to-Baryon Mass Ratio of Clusters of Galaxies

We derive the ratio of total blue luminosity to total baryon mass, LB/Mb, formassive (Mgas at the Abell radius is \ge 1 \times 10^{13} h^{-2.5} \Msolar)clusters of galaxies up to z \simeq 1 from the literature. Twenty-two clustersin our sample are at z > 0.1. Assuming that the relative mix of hot gas andgalaxies in clusters does not change during cluster evolution, we use LB/Mb toprobe the star formation history of the galaxy population as a whole inclusters. We find that LB/Mb of clusters increases with redshift fromLB/Mb=0.024 (solar units) at z = 0 to \simeq 0.06 at z=1, indicating a factorof 2-3 brightening (we assume H0=70 km/s/Mpc). This amount of brightening isalmost identical to the brightening of the M/LB ratio of early-type galaxies inclusters at 0.02 \le z \le 0.83 reported by van Dokkum et al. (1998). Wecompare the observed brightening of LB/Mb with luminosity evolution models forthe galaxy population as a whole, changing the e-folding time of star formation\tau by 0.1 \le \tau \le 5 Gyr and the formation redshift \zF by 2 \le \zF <\infty. We find that \tau=0.1 Gyr 'single burst' models with \zF \ge 3 and\tau=5 Gyr 'disk' models with arbitrary \zF are consistent with the observedbrightening, while models with \tau=1-2 Gyr tend to predict too steepbrightening. We also derive the ratio of blue luminosity density to baryondensity for field galaxies, adopting \Omega_b h^2 = 0.02, and find that blueluminosity per unit baryon is similar in clusters and in fields up to z \simeq1 within the observational uncertainties.Comment: 10 pages, LaTeX (PASJ2.sty, PASJ95.sty, PASJadd.sty), 10 PostScript figures, accepted for publication in PAS