Mass distribution in the core of MACS J1206

Robust modeling from an exceptionally large sample of central multiple images

¹ Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, via Saragat 1, 44122 Ferrara, Italy
e-mail: gbcaminha@fe.infn.it
² INAF–Osservatorio Astronomico di Bologna, via Gobetti 93/3, 40129 Bologna, Italy
³ Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano, Italy
⁴ Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
⁵ INFN – Sezione di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
⁶ INAF–Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Napoli, Italy
⁷ University Observatory Munich, Scheinerstrasse 1, 81679 Munich, Germany
⁸ INAF–Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34143 Trieste, Italy
⁹ Institute of Astronomy and Astrophysics, Academia Sinica, PO Box 23-141, 10617 Taipei, Taiwan
¹⁰ Dipartimento di Fisica, Università degli Studi di Trieste, via G. B. Tiepolo 11, 34143 Trieste, Italy
¹¹ INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 50125 Firenze, Italy
¹² Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Philosophenweg 12, 69120 Heidelberg, Germany
¹³ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21208, USA
¹⁴ Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen, The Netherlands
¹⁵ Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
¹⁶ INAF–Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF) Milano, via E. Bassini 15, 20133 Milano, Italy
¹⁷ School of Physics, Korea Institute for Advanced Study, Hoegiro 85, Dongdaemun-gu, 02455 Seoul, Republic of Korea
¹⁸ Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, 85748 Garching, Germany
¹⁹ Physics Department, Ben-Gurion University of the Negev, PO Box 653, 84105 Be’er-Sheva, Israel

Received: 3 July 2017
Accepted: 8 September 2017

Abstract

We present a new strong lensing analysis of the galaxy cluster MACS J1206.2−0847 (MACS 1206), at z = 0.44, using deep spectroscopy from CLASH-VLT and VLT/MUSE archival data in combination with imaging from the Cluster Lensing and Supernova survey with Hubble. MUSE observations enable the spectroscopic identification of 23 new multiply imaged sources, extending the previous compilations by a factor of approximately five. In total, we use the positional measurements of 82 spectroscopic multiple images belonging to 27 families at z = 1.0−6.1 to reconstruct the projected total mass distribution of MACS 1206. Remarkably, 11 multiple images are found within 50 kpc of the brightest cluster galaxy, making this an unprecedented set of constraints for the innermost projected mass distribution of a galaxy cluster. We thus find that, although dynamically relaxed, the smooth matter component (dark matter plus hot gas) of MACS 1206 shows a significant asymmetry, which closely follows the asymmetric distribution of the stellar component (galaxy members and intracluster light). We determine the value of the innermost logarithmic slope of the projected total mass density profile and find it to be close to the canonical Navarro-Frenk-White value. We demonstrate that this quantity is very robust against different parametrizations of the diffuse mass component;however, this is not the case when only one central image is used in the mass reconstruction. We also show that the mass density profile from our new strong lensing model is in very good agreement with dynamical and X-ray measurements at larger radii, where they overlap.