Combined strong and weak lensing analysis of 28 clusters from the Sloan Giant Arcs Survey★

Abstract

We study the mass distribution of a sample of 28 galaxy clusters using strong and weak lensing observations. The clusters are selected via their strong lensing properties as part of the Sloan Giant Arcs Survey (SGAS) from the Sloan Digital Sky Survey (SDSS). Mass modelling of the strong lensing information from the giant arcs is combined with weak lensing measurements from deep Subaru/Suprime-cam images to primarily obtain robust constraints on the concentration parameter and the shape of the mass distribution. We find that the concentration c vir is a steep function of the mass, c vir ∝ M −0.59±0.12 vir , with the value roughly consistent with the lensing-bias-corrected theoretical expectation for high-mass (∼10 15 h −1 M ) clusters. However, the observationally inferred concentration parameters appear to be much higher at lower masses (∼10 14 h −1 M ), possibly a consequence of the modification to the inner density profiles provided by baryon cooling. The steep mass-concentration relation is also supported from direct stacking analysis of the tangential shear profiles. In addition, we explore the 2D shape of the projected mass distribution by stacking weak lensing shear maps of individual clusters with prior information on the position angle from strong lens modelling, and find significant evidence for a large mean ellipticity with the best-fitting value of e = 0.47 ± 0.06 for the mass distribution of the stacked sample. We find that the luminous cluster member galaxy distribution traces the overall mass distribution very well, although the distribution of fainter cluster galaxies appears to be more extended than the total mass.

LoCuSS: weak-lensing mass calibration of galaxy clusters

“…In common with several authors (e.g. Umetsu et al 2010;Oguri et al 2012;Okura & Futamase 2012;Umetsu et al 2015a) we have found that this dependence can be reduced significantly for KSB shape measurement methods if the galaxies upon which the isotropic PSF correction is based are limited to those detected at high signal-to-noise ratio (Okabe et al 2013). We therefore calibrate the isotropic PSF correction, using galaxies detected at very high significance, i.e.…”

“…The weighting wn (e.g. Hoekstra, Franx & Kuijken 2000;Hamana et al 2003;Okabe et al 2010a;Umetsu et al 2010;Oguri et al 2012) is used to down-weight galaxies whose shapes are less reliably measured, based on the uncertainty in the shape measurement, σg,n, given by…”

“…Each galaxy is characterized by bulge and disc components, with Sersic profiles indices of n = 4 and 1, respectively. Galaxy images are convolved with a PSF model based on the Moffat profile Σ(R) ∝ 1 + (R/a) 2 −β , with seeing in the range 0.5 FWHM 1arcsec and the Moffat profile with power slopes 3 < β < 12, as described in Oguri et al (2012). A number of fits frames matching the Suprime-Cam field of view were produced and analysed using the pipeline described in §2.4.…”

“Refsdal” Meets Popper: Comparing Predictions of the Re-Appearance of the Multiply Imaged Supernova Behind MACSJ1149.5+2223

“…In addition, the second-order (external shear) and third-order perturbations are included so as to account for asymmetry of the overall lens potential. Interested readers are referred to Oguri (2010Oguri ( , 2015, Oguri et al (2012Oguri et al ( , 2013, and Ishigaki et al (2015) for more detailed descriptions and examples of cluster mass modeling with GLAFIC. Additional details are given in a dedicated paper .…”

What if LIGO’s gravitational wave detections are strongly lensed by massive galaxy clusters?

“…We have assembled a list of 130 spectroscopically confirmed strong cluster lenses from the literature, drawing mainly on HST studies of X-ray selected clusters, and strong-lensing clusters from the Sloan Digital Sky Survey (Smith et al 2005(Smith et al , 2009Limousin et al 2007Limousin et al , 2012Richard et al 2010;Christensen et al 2012;Oguri et al 2012;Jauzac et al 2015;Paraficz et al 2016;Umetsu et al 2016). We compare the celestial coordinates of these clusters with the sky localization maps of the BBH merger detections from 2015, finding that none of the known strong-lensing clusters are located The sky localizations of all three GW events intersect the disc of the Milky Way.…”