Strong-lensing Measurement of the Mass-density Profile out to 3 Effective Radii for $z \sim 0.5$ Early-type Galaxies

Rui Li, Yiping Shu, Jiangcheng Wang

Published 2018-05-17Version 1

We obtain the total mass-density profiles out to three effective radii for a sample of 63 intermediate-redshift early-type galaxies (ETGs) through a joint analysis of strong gravitational lensing and stellar dynamics. The sample is compiled from three galaxy-scale strong-lens surveys, including the Baryon Oscillation Spectroscopic Survey (BOSS) Emission-Line Lens Survey (BELLS), BELLS for GALaxy-Ly EmitteR sYstems (BELLS GALLERY) Survey, and Strong Lensing Legacy Survey (SL2S). The lens redshifts of the sample have a mean value of $0.52$, but the source redshifts span a wide range from $0.8$ to $3.5$, which leads to a wide range of Einstein radii up to three effective radii. We find that: (1) the total mass distribution is very close to isothermal one with the average logarithmic density slope $\langle\gamma\rangle=2.000_{-0.032}^{+0.033}$ ($68\%$CL) and intrinsic scatter $\delta=0.180_{-0.028}^{+0.032}$, similar with previous work. (2) we normalize the Einstein radius by the effective radius to study whether the slope $\gamma$ evolutes along radius for a fixed galaxy. We find the density profile would be steeper with increasing radius. Therefore, We conclude that the total mass-density slope have a slight increasing trend along radius for a fixed galaxy, which is consistent with previous numerical simulation depending on galactic wind and AGN feedback