Journal Article

Strong-lensing analysis of a complete sample of 12 MACS clusters at <i>z</i> > 0.5: mass models and Einstein radii

Adi Zitrin, Tom Broadhurst, Rennan Barkana, Yoel Rephaeli and Narciso Benítez

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 410, issue 3, pages 1939-1956
Published in print January 2011 | ISSN: 0035-8711
Published online January 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17574.x
Strong-lensing analysis of a complete sample of 12 MACS clusters at z > 0.5: mass models and Einstein radii

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We present the results of a strong-lensing analysis of a complete sample of 12 very luminous X-ray clusters at z > 0.5 using HST/ACS images. Our modelling technique has uncovered some of the largest known critical curves outlined by many accurately predicted sets of multiple images. The distribution of Einstein radii has a median value of ≃28 arcsec (for a source redshift of zs∼ 2), twice as large as other lower z samples, and extends to 55 arcsec for MACS J0717.5+3745, with an impressive enclosed Einstein mass of 7.4 × 1014 M. We find that nine clusters cover a very large area (>2.5 arcmin2) of high magnification (μ > 10×) for a source redshift of zs∼ 8, providing primary targets for accessing the first stars and galaxies. We compare our results with theoretical predictions of the standard Λ cold dark matter (ΛCDM) model which we show systematically fall short of our measured Einstein radii by a factor of ≃1.4, after accounting for the effect of lensing projection. Nevertheless, a revised analysis, once arc redshifts become available, and similar analyses of larger samples, is needed in order to establish more precisely the level of discrepancy with ΛCDM predictions.

Keywords: gravitational lensing: strong; galaxies: clusters: general; galaxies: clusters: individual: MACS z > 0.5 sample; dark matter

Journal Article.  12880 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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