2006/11/17 by Roeland P. van der Marel, Pieter G. van Dokkum · 5 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Elliptical galaxy #Fundamental plane (elliptical galaxies) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Plane (geometry) #Population #Sample (material) #Stellar, planetary, and galactic studies #Time evolution #astro-ph
paper · pdf · doi:10.1086/521211
ApJ, submitted; 17 pages formatted with emulateapj
arxiv created 2006/11/17 · openalex publication_date 2007/10/19 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study the mass-to-light ratio ( M / L ) evolution of early-type galaxies using dynamical modeling of resolved internal kinematics. This makes fewer assumptions than fundamental plane (FP) studies and provides a powerful new approach for studying galaxy evolution. We focus on the sample of 25 galaxies in clusters at z ≈ 0.5 modeled in Paper I. For comparison, we compile and homogenize M / L literature data for 60 nearby galaxies that were modeled in comparable detail. The nearby sample obeys log( M / L ) B = Z + S log(σ eff /200 km s -1 ), where Z = 0.896 ± 0.010, S = 0.992 ± 0.054, and σ eff is the effective velocity dispersion. The z ≈ 0.5 sample follows a similar relation, but with lower zero point. The implied M / L evolution is Δ log( M / L )/Δ z = -0.457 ± 0.046(random) ± 0.078(systematic), consistent with passive evolution following high-redshift formation. This agrees with the FP results for this sample by van Dokkum & van der Marel, and confirms that FP evolution tracks M / L evolution, which is an important verification of the assumptions that underlie FP studies. However, while we find more FP evolution for galaxies of low σ eff (or low mass), the dynamical M / L evolution shows little correlation with σ eff . We argue that this difference can be plausibly attributed to a combination of two effects: (1) evolution in structural galaxy properties other than M / L , and (2) the neglect of rotational support in studies of FP evolution. The results leave the question open as to whether the low-mass galaxies in the sample have younger populations than the high-mass galaxies. This highlights the general importance in the study of population ages for complementing dynamical measurements with broadband colors or spectroscopic population diagnostics.