2003/06/05 by D. Rusin, C. S. Kochanek, C. R. Keeton · 11 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Dark matter #Einstein radius #Fundamental plane (elliptical galaxies) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gravitational lens #Lens (geology) #Mass-to-light ratio #Statistical Mechanics and Entropy #Stellar mass #Strong gravitational lensing #astro-ph
paper · pdf · doi:10.1086/377356
published as Astrophys.J.595:29-42,2003 · 30 pages including 6 figures, to be published in ApJ
arxiv created 2003/06/05 · openalex publication_date 2003/09/16 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We introduce a self-similar mass model for early-type galaxies and constrain it using the aperture mass-radius relations determined from the geometries of 22 gravitational lenses. The model consists of two components: a concentrated component, which traces the light distribution, and a more extended power-law component (ρ ∝ r - n ), which represents the dark matter. We find that lens galaxies have total mass profiles that are nearly isothermal, or slightly steeper, on the several-kiloparsec radial scale spanned by the lensed images. In the limit of a single-component, power-law radial profile, the model implies n = 2.07 ± 0.13, consistent with isothermal ( n = 2). Models in which mass traces light are excluded at higher than 99% confidence. An n = 1 cusp (such as the Navarro-Frenk-White profile) requires a projected dark matter mass fraction of f cdm = 0.22 ± 0.10 inside two effective radii. These are the best statistical constraints yet obtained on the mass profiles of lenses and provide clear evidence for a small but nonzero dark matter mass fraction in the inner regions of early-type galaxies. In addition, we derive the first strong-lensing constraint on the relation between the stellar mass-to-light ratio ϒ and galaxy luminosity L , ϒ ∝ L , which is consistent with the relation suggested by the fundamental plane. Finally, we apply our self-similar mass models to current problems regarding the interpretation of time delays and flux ratio anomalies in gravitational lens systems.