We measure the evolution of the luminous red galaxy (LRG) luminosity function in the redshift range 0.1 < z < 0.9 using samples of galaxies from the Sloan Digital Sky Survey as well as new spectroscopy of high-redshift massive red galaxies. Our high-redshift sample of galaxies is largest spectroscopic sample of massive red galaxies at z ∼ 0.9 collected to date and covers 7 deg2, minimizing the impact of large-scale structure on our results. We find that the LRG population has evolved little beyond the passive fading of its stellar populations since z ∼ 0.9. Based on our luminosity function measurements and assuming a nonevolving Salpeter stellar initial mass function, we find that the most massive (L > 3L*) red galaxies have grown by less than 50% (at 99% confidence), since z = 0.9, in stark contrast to the factor of 2-4 growth observed in the L* red galaxy population over the same epoch. We also investigate the evolution of the average LRG spectrum since z ∼ 0.9 and find the high-redshift composite to be well described as a passively evolving example of the composite galaxy observed at low redshift. From spectral fits to the composite spectra, we find at most 5% of the stellar mass in massive red galaxies may have formed within 1 Gyr of z = 0.9. While L* red galaxies are clearly assembled at z < 1, 3L* galaxies appear to be largely in place and evolve little beyond the passive evolution of their stellar populations over the last half of cosmic history.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science