2001/01/10 by Charles R. Keeton, Piero Madau · 1 citation
Environmental Science · Physics and Astronomy · #Galaxies: Formation, Evolution, Phenomena #Remote Sensing in Agriculture #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.1086/319136
accepted for publication in ApJL; 5 pages, 2 figures, emulateapj
arxiv created 2001/01/10 · openalex publication_date 2001/03/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
The statistics of wide-separation (6'' < θ < 15'') gravitational lenses constrain the amount of mass in the cores of dark matter halos on group and cluster mass scales. For a family of halo models with a central cusp ρ ∝ r -α (1.0 ≤ α ≤ 1.9), the lack of wide-separation lenses in the large Cosmic Lens All-Sky Survey yields an upper limit on the fraction of the halo mass that is contained within ~4% of the virial radius, f core < 0.023 (95% confidence level, Λ cold dark matter). This limit offers an important test of the cold dark matter paradigm. While the halo profiles derived from numerical simulations appear to be consistent with this upper limit, larger surveys currently underway such as the Two-degree Field and Sloan Digital Sky Survey should detect wide-separation lenses and thus provide a measurement of the core mass fraction in massive dark matter halos.