Morphological Evolution and the Ages of Early-Type Galaxies in Clusters

By P. V. van Dokkum, M. Franx. 2001

236 citations recorded by the source corpus.

Morphological and spectroscopic studies of high-redshift clusters indicate that a significant fraction of present-day, early-type galaxies was transformed from star-forming galaxies at z < 1. On the other hand, the slow luminosity evolution of early-type galaxies and the low scatter in their color-magnitude relation indicate a high formation redshift of their stars. In this paper we construct models that reconcile these apparently contradictory lines of evidence, and we quantify the effects of morphological evolution on the observed photometric properties of early-type galaxies in distant clusters. We show that in the case of strong morphological evolution the apparent luminosity and color evolution of early-type galaxies are similar to those of a single-age stellar population formed at z = ∞, irrespective of the true star formation history of the galaxies. Furthermore, the scatter in age, and hence the scatter in color and luminosity, is approximately constant with redshift. These results are consequences of the "progenitor bias": the progenitors of the youngest low-redshift, early-type galaxies drop out of the sample at high redshift. We construct models that reproduce the observed evolution of the number fraction of early-type galaxies in rich clusters and their color and luminosity evolution simultaneously. Our modeling indicates that ~50% of early-type galaxies were transformed from other galaxy types at z < 1, and their progenitor galaxies may have had roughly constant star formation rates prior to morphological transformation. The effect of the progenitor bias on the evolution of the mean M/L ratio and color can be estimated. The progenitor bias is a linear function of the scatter in the color-magnitude relation produced by age variations and is maximal if the observed scatter is entirely due to age differences. After correcting the observed evolution of the mean M/LB ratio for the maximum progenitor bias, we find that the mean luminosity-weighted formation redshift of stars in early-type galaxies ⟨z*⟩ = 3.0 for Ωm = 0.3 and ΩΛ = 0 and ⟨z*⟩ = 2.0 for Ωm = 0.3 and ΩΛ = 0.7. Our analysis places the star formation epoch of early-type galaxies later than previous studies, which ignored the effects of progenitor bias. The results are consistent with the idea that (some) Lyman break galaxies are star-forming building blocks of massive early-type galaxies in clusters.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/a5b5ab4d63d263bd901d1ee8b68f068ebca6ae71

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Citations in the corpus

Improved constraints on the expansion rate of the Universe up to z ∼ 1.1 from the spectroscopic evolution of cosmic chronometers (2012, methodology): “To cross-check the results obtained with the model introduced above, we also studied the theoretical models which predicts the effect of the progenitor-bias from van Dokkum & Franx (2001)(4) (hereafter vDF, [90]); we refer to this reference for a detailed discussion about the parameters used to set ”
The formation of massive, compact galaxies at z = 2 in the Illustris simulation (2014, background): “It is possible that the observed growth in size of quiescent galaxies with time is due not to the growth of individual galaxies, but to the continual addition of larger galaxies to the quiescent population (progenitor bias, van Dokkum & Franx (2001), see also Carollo et al. (2013)).”
A New Approach to Galaxy Morphology. I. Analysis of the Sloan Digital Sky Survey Early Data Release (2003, methodology): “…calibrate evolution in the same manner that position relative to the local Tully-Fisher and fundamental plane relations has provided robust calibrators for evolution in size, surface brightness, and mass-to-light ratio (Vogt et al. 1997; Vogt 2001; van Dokkum et al. 2001; van Dokkum & Franx 2001).”
Probing the Coevolution of Supermassive Black Holes and Galaxies Using Gravitationally Lensed Quasar Hosts (2006, background): “Adopting a higher formation redshift has little effect since the fading rate only changes from dMR/dz ≃ −0.8 mag for zf = 5 to dMR/dz ≃ −0.6 mag for zf → ∞ in the Bruzual & Charlot (2003) population synthesis models, with solar metallicity, Salpeter IMF, and no reddening (van Dokkum & Franx 2001).”
THE EVOLUTION OF X-RAY CLUSTERS OF GALAXIES (2002, background): “…properties of galaxy groups; Birkinshaw (1999) and Carlstrom et al. (2001) for cluster studies with the Sunyaev–Zeldovich effect; Mellier (1999) for studies of the mass distribution of clusters via gravitational lensing and van Dokkum & Franx (2001) for the study of galaxy populations in clusters.”
The size evolution of star-forming and quenched galaxies in the IllustrisTNG simulation (2017, background): “…that quenched galaxies at a given mass are observed to be smaller than star-forming ones, the quenched population size growth can be achieved merely by the continuous addition of larger star-forming galaxies as more and more of them quench over time (van Dokkum & Franx 2001; Carollo et al. 2013).”
Galaxy Luminosity Functions to z~1 from DEEP2 and COMBO-17: Implications for Red Galaxy Formation (2005, background): “…(and their associated stellar mass) has been growing over time, the makeup of the population is not stable, and mean properties such as average color, stellar age, etc., are constantly being skewed by recent arrivals (the so-called “progenitor bias” phenomenon of van Dokkum & Franx (2001)).”