The Cluster Lensing and Supernova Survey with Hubble (CLASH): Strong-Lensing analysis of A383 from 16-band HST/WFC3/ACS Imaging

We examine the inner mass distribution of the relaxed galaxy cluster A383 (z = 0.189), in deep 16band Hubble Space Telescope/ACS+WFC3 imaging taken as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) multi-cycle treasury program. Our program is designed to study the dark matter distribution in 25 massive clusters, and balances depth with a wide wavelength coverage, 2000-16000 Å, to better identify lensed systems and generate precise photometric redshifts. This photometric information together with the predictive strength of our strong-lensing analysis method identifies 13 new multiply lensed images and candidates, so that a total of 27 multiple images of nine systems are used to tightly constrain the inner mass profile gradient, dlog Σ/dlog r ≃ -0.6 0.1 (r < 160kpc). We find consistency with the standard distance-redshift relation for the full range spanned by the lensed images, 1.01 < z < 6.03, with the higher-redshift sources deflected through larger angles as expected. The inner mass profile derived here is consistent with the results of our independent weak-lensing analysis of wide-field Subaru images, with good agreement in the region of overlap (0.7-1 arcmin). Combining weak and strong lensing, the overall mass profile is well fitted by a Navarro-Frenk-White profile with M _vir = (5.37 ^+0.70 _{- 0.63}± 0.26) × 10¹⁴ M _⊙ h ^-1 and a relatively high concentration, c _vir = 8.77^+0.44 _{- 0.42}± 0.23, which lies above the standard c-M relation similar to other well-studied clusters. The critical radius of A383 is modest by the standards of other lensing clusters, r_E ≃ 16 2″ (for z_s = 2.55), so the relatively large number of lensed images uncovered here with precise photometric redshifts validates our imaging strategy for the CLASH survey. In total we aim to provide similarly high-quality lensing data for 25 clusters, 20 of which are X-ray-selected relaxed clusters, enabling a precise determination of the representative mass profile free from lensing bias.