MUSE spectroscopy and deep observations of a unique compact JWST target, lensing cluster CLIO

Alex Griffiths, Christopher J. Conselice, Mehmet Alpaslan, Brenda L. Frye, Jose M. Diego, Adi Zitrin, Haojing Yan, Zhiyuan Ma, Robert Barone-Nugent, Rachana Bhatawdekar, Simon P. Driver, Aaron S.G. Robotham, Rogier A. Windhorst, J. Stuart B. Wyithe

Research output: Contribution to journalArticlepeer-review


We present the results of a VLT MUSE/FORS2 and Spitzer survey of a unique compact lensing cluster CLIO at z = 0.42, discovered through the GAMA survey using spectroscopic redshifts. Compact and massive clusters such as this are understudied, but provide a unique prospective on dark matter distributions and for finding background lensed high-z galaxies. The CLIO cluster was identified for follow-up observations due to its almost unique combination of high-mass and dark matter halo concentration, as well as having observed lensing arcs from ground-based images. Using dual band optical and infra-red imaging from FORS2 and Spitzer, in combination with MUSE optical spectroscopy we identify 89 cluster members and find background sources out to z = 6.49. We describe the physical state of this cluster, finding a strong correlation between environment and galaxy spectral type. Under the assumption of an NFW profile, we measure the total mass of CLIO to be M200 = (4.49 ± 0.25) × 1014 M. We build and present an initial strong-lensing model for this cluster, and measure a relatively low intracluster light (ICL) fraction of 7.21 ± 1.53 per cent through galaxy profile fitting. Due to its strong potential for lensing background galaxies and its low ICL, the CLIO cluster will be a target for our 110 h James Webb Space Telescope 'Webb Medium-Deep Field' (WMDF) GTO program.

Original languageAmerican English
Pages (from-to)2853-2869
Number of pages17
Issue number3
StatePublished - 1 Apr 2018


  • galaxies: clusters: general
  • gravitational lensing: strong
  • techniques: imaging spectroscopy

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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