Strong-lensing measurement of the total-mass-density profile out to three effective radii for z ∼ 0.5 early-type galaxies. Issue 1 (27th July 2018)

• Record Type: Journal Article
• Authors: Li, Rui; Shu, Yiping; Wang, Jiancheng
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 480:Issue 1(2018)
• Page Start: 431
• Page End: 438
• Publication Date: 2018-07-27
• Subjects: gravitational lensing: strong -- galaxies: elliptical and lenticular, cD -- galaxies: structure; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty1813
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We measure the total-mass-density profiles out to three effective radii for a sample of 63$z$ ∼ 0.5, massive early-type galaxies (ETGs) acting as strong gravitational lenses through a joint analysis of lensing and stellar dynamics. The compilation is selected from three galaxy-scale strong-lens samples, namely the Baryon Oscillation Spectroscopic Survey (BOSS) Emission-Line Lens Survey (BELLS), the BELLS for GALaxy-Lyα EmitteR sYstems Survey (BELLS GALLERY), and the Strong Lensing Legacy Survey (SL2S). Utilizing the wide source-redshift coverage (0.8–3.5) provided by these three samples, we build a statistically significant ensemble of massive ETGs for which robust mass measurements can be achieved within a broad range of Einstein radii up to three effective radii. Characterizing the three-dimensional total-mass-density distribution by a power-law profile as ρ ∝ r −γ, we find that the average logarithmic density slope for the entire sample is $\langle \gamma \rangle =2.000_{-0.032}^{+0.033}$ (68 per cent CL) with an intrinsic scatter of $\delta =0.180_{-0.028}^{+0.032}$ . Further parametrizing 〈γ〉 as a function of redshift $z$ and the ratio of Einstein radius to effective radius R ein / R eff, we find that the average density distributions of these massive ETGs become steeper at later cosmic times and at larger radii, with magnitudes $\mathrm{d} \langle \gamma \rangle / \mathrm{d}z=-0.309_{-0.160}^{+0.166}$ and $\mathrm{d} \langle \gamma \rangle / \mathrm{d} \log _{10} ({R_{\rm ein}}/{R_{\rm eff}})=0.194_{-0.083}^{+0.092}$ .