Adam S. Bolton, Joel R. Brownstein, Christopher S. Kochanek, Yiping Shu, David J. Schlegel, Daniel J. Eisenstein, David A. Wake, Natalia Connolly, Claudia Maraston, Benjamin A. Weaver
We present an analysis of the evolution of the central mass-density profile
of massive elliptical galaxies from the SLACS and BELLS strong gravitational
lens samples over the redshift interval z ~ 0.1--0.6. We find a significant
trend towards steeper mass profiles (parameterized by the power-law density
model with rho propto r^[-gamma]) at later cosmic times, with magnitude
d/dz = -0.56 +/- 0.14. We show that this detection cannot be explained
by variations in the lensing measurement aperture with redshift. This result
suggests that major dry mergers involving off-axis trajectories play a
significant role in the secular evolution of the average mass-density structure
of massive galaxies over the past 6 Gyr.
View original:
http://arxiv.org/abs/1201.2988
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