2024/08/19 by William Sheu, Anowar J. Shajib, Sheu, William +13 · 2 citations
Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.2408.10316
openalex publication_date 2024/08/19 · openalex created_date 2024/10/01 · openalex updated_date 2026/07/28
We present a new measurement of the dark and luminous matter distribution of massive elliptical galaxies, and their evolution with redshift, by combining strong lensing and dynamical observables. Our sample of 56 lens galaxies covers a redshift range of 0.090 ≤ z\rm l ≤ 0.884. By combining new Hubble Space Telescope imaging with previously observed velocity dispersion and line-of-sight measurements, we decompose the luminous matter profile from the dark matter profile and perform a Bayesian hierarchical analysis to constrain the population-level properties of both profiles. We find that the inner slope of the dark matter density profile ("cusp"; ρ\rm DM ∝ r^-γ\rm in) is consistent (μ_γ\rm in=0.97+0.03-0.03 with ≤0.07 intrinsic scatter) with a standard Navarro-Frenk-White (NFW; γ\rm in=1) at z=0.35. Additionally, we find an appreciable evolution with redshift (dlog(γ\rm in)/dz=-0.44+0.14-0.15) resulting in a shallower slope (of > 2 σ tension from NFW) at redshifts z ≥ 0.49. This is in excellent agreement with previous population-level observational studies, as well as with predictions from hydrodynamical simulations such as IllustrisTNG. We also find the stellar mass-to-light ratio at the population level is consistent with that of a Salpeter initial mass function, a small stellar mass-to-light gradient (κ*(r)∝ r-η, with η ≤ 5 × 10-5), and isotropic stellar orbits. Our averaged total mass density profile is consistent with a power-law profile within 0.25 to 4 Einstein radii (γ = 2.24 ± 0.14), with an internal mass-sheet transformation parameter λ = 0.96 ± 0.03 consistent with no mass sheet. Our findings confirm the validity of the standard mass models used for time-delay cosmography.