2003/11/10 by A. C. Edge, Alastair C. Edge, G. P. Smith +9
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Brightest cluster galaxy #Cluster (spacecraft) #Dark matter #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Gravitation #Gravitational lens #Gravitational potential #Halo #Mass distribution #Physics #Redshift #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/381193
published as Astrophys.J. 599 (2003) L69-L72 · 11 pages, 2 figures, ApJ Letters accepted
arxiv created 2003/11/10 · openalex publication_date 2003/12/03 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present a snapshot Hubble Space Telescope (HST) image of the galaxy cluster A1201 (z=0.169), revealing a tangential arc 2 from the brightest cluster galaxy (BCG). Keck Echelle Spectrograph and Imager (ESI) spectroscopy confirms that the arc is gravitational in nature and that the source galaxy lies at z=0.451. We construct a model of the gravitational potential of the cluster that faithfully reproduces the observed arc morphology. Despite the relaxed appearance of the cluster in the HST frame, the best-fit ellipticity of the total matter distribution is total0.5, in contrast to the light distribution of the BCG (BCG=0.23±0.03) on 2 scales. Further deep optical observations and pointed X-ray spectro-imaging observations with Chandra are required to determine whether this elongation is due to a single elongated dark matter halo or a more complex distribution of matter in the cluster core. We compare the arc with a sample drawn from the published literature and confirm that it is unique among tangential systems in the small physical scales that it probes (6 kpc). In anticipation of a more thorough investigation of this cluster across a broad range of physical scales, we use our fiducial lens model to estimate the projected mass and mass-to-light ratio of the cluster within a radius of 6 kpc, obtaining M=(5.9+0.9-0.7)×1011 M, M/LV=9.4+2.4-2.1 (M/L). Overall our results confirm the importance of HST snapshot surveys for identifying rare lensing constraints on cluster mass distributions. In combination with follow-up optical and X-ray observations, the arc in A1201 should help to increase our understanding of the physics of cluster cores.