Journal
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 473, Issue 1, Pages 969-983Publisher
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stx2390
Keywords
galaxies: elliptical and lenticular, cD; galaxies: evolution; galaxies: general; galaxies: structure
Categories
Funding
- NWO-VICI [639.043.308]
- Alexander von Humboldt Foundation
- Netherlands Research School for Astronomy (NOVA)
- Target
- Samenwerkingsverband Noord Nederland
- European fund for regional development
- Dutch Ministry of economic affairs
- Pieken in de Delta
- Province of Groningen
- Province of Drenthe
- ESO Telescopes at the La Silla Paranal Observatory [177.A-3016, 177.A-3017, 177.A3018]
- NOVA
- NWO-M
- Department of Physics and Astronomy of the University of Padova
- Department of Physics of Univ. Federico II (Naples)
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We study the dark matter (DM) assembly in the central regions of massive early-type galaxies up to z similar to 0.65. We use a sample of similar to 3800 massive (logM(star)/M-circle dot > 11.2) galaxies with photometry and structural parameters from 156 deg(2) of the Kilo Degree Survey (KiDS), and spectroscopic redshifts and velocity dispersions from Sloan Digital Sky Survey (SDSS). We obtain central total-to-stellar mass ratios, M-dyn/M-star, and DM fractions, by determining dynamical masses, M-dyn, from Jeans modelling of SDSS aperture velocity dispersions and stellar masses, M-star, from KiDS galaxy colours. We first show how the central DM fraction correlates with structural parameters, mass and density proxies, and demonstrate that most of the local correlations are still observed up to z similar to 0.65; at fixed M-star, local galaxies have larger DM fraction, on average, than their counterparts at larger redshift. We also interpret these trends with a non- universal initial mass function (IMF), finding a strong evolution with redshift, which contrast independent observations and is at odds with the effect of galaxy mergers. For a fixed IMF, the galaxy assembly can be explained, realistically, by mass and size accretion, which can be physically achieved by a series of minor mergers. We reproduce both the R-e-M-star and M-dyn/M-star-M-star evolution with stellar and dark mass changing at a different rate. This result suggests that the main progenitor galaxy is merging with less massive systems, characterized by a smaller M-dyn/M-star, consistently with results from halo abundance matching.
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