Subaru Weak Lensing Study of Seven Merging Clusters: Distributions of Mass and Baryons

By N. Okabe, Keiichi Umetsu Tohoku Univ., Asiaa. 2007

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We present and compare projected distributions of mass, galaxies, and the intracluster medium (ICM) for a sample of merging clusters of galaxies based on the joint weak-lensing, optical photometric, and X-ray analysis. Our sample comprises seven nearby Abell clusters, for which we have conducted systematic, deep imaging observations with Suprime-Cam on Subaru telescope. Our seven target clusters, representing various merging stages and conditions, allow us to investigate in details the physical interplay between dark matter, ICM, and galaxies associated with cluster formation and evolution. A1750 and A1758 are binary systems consisting of two cluster-sized components, A520, A754, A1758N, A1758S, and A1914 are on-going cluster mergers, and A2034 and A2142 are cold-front clusters. In the binary clusters, the projected mass, optical light, and X-ray distributions are overall similar and regular without significant substructures. On-going and cold-front merging clusters, on the other hand, reveal highly irregular mass distributions. Overall the mass distribution appears to be similar to the galaxy luminosity distribution, whereas their distributions are quite different from the ICM distribution in a various ways. We also measured for individual targets the global cluster parameters such as the cluster mass,the mass-to-light ratio, and the ICM temperature. A comparison of the ICM and virial temperatures of merging clusters from X-ray and weak-lensing analyses, respectively, shows that the ICM temperature of on-going and cold-front clusters is significantly higher than the cluster virial temperature by a factor of $\sim 2$. This temperature excess in the ICM could be explained by the effects of merger boosts.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d2559ab3eecdf3bcc428035a5b7237143a39c832

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Citations in the corpus

X-ray–optical classification of cluster mergers and the evolution of the cluster merger fraction (2011, background): “…the Royal Astronomical Society C© 2012 RAS Downloaded from https://academic.oup.com/mnras/article-abstract/420/3/2120/978455 by guest on 29 July 2018 2134 A. W. Mann and H. Ebeling discrepancy between mass estimates based on X-ray and weaklensing analyses (Okabe & Umetsu 2008; Zhang et al. 2010).”
Combining Lens Distortion and Depletion to Map the Mass Distribution of A1689 (2007, methodology): “…αn2Cζm+1,n+1 + αm1 αn1Cζm,n −αm1 αn2Cζm,n+1 − αm2 αn1Cζm+1,n,(50) where Cζmn ≡ 〈δζmδζn〉 is the bin-to-bin error covariance matrix of the aperture densitometry measurements which is calculated by propagating the rms errors σ+(θm) for the tangential shear measurement (Okabe & Umetsu 2008).”
LoCuSS: Subaru Weak Lensing Study of 30 Galaxy Clusters (2009, methodology): “…the collisionless nature of dark matter should result in the merger signatures surviving longer in the dark matter distribution that dominates weak lensing maps compared to the intra-cluster hot gas (e.g., see Okabe & Umetsu 2008 for the observational; and Tormen et al. 2004 theoretical studies).”
Detailed cluster lensing profiles at large radii and the impact on cluster weak lensing studies (2011, background): “…massive clusters, we can detect weak lensing signals out to virial radii, which allows direct measurements of virial masses (e.g., Dahle 2006; Broadhurst et al. 2008; Mahdavi et al. 2008; Okabe & Umetsu 2008; Oguri et al. 2009; Umetsu et al. 2009, 2011; Medezinski et al. 2010; Okabe et al. 2010).”
Creation of cosmic structure in the complex galaxy cluster merger Abell 2744 (2011, methodology): “The data were reduced following Okabe & Umetsu (2008) and Okabe et al. (2010,a).”
CLASH: WEAK-LENSING SHEAR-AND-MAGNIFICATION ANALYSIS OF 20 GALAXY CLUSTERS (2014, methodology): “Our KSB+ implementation has been applied extensively to Subaru observations of a large number of clusters (e.g., Umetsu & Broadhurst 2008; Okabe & Umetsu 2008; Umetsu et al. 2009, 2010, 2011b, 2012; Medezinski et al. 2010, 2011, 2013; Coe et al. 2012).”
MEASURING THE ULTIMATE HALO MASS OF GALAXY CLUSTERS: REDSHIFTS AND MASS PROFILES FROM THE HECTOSPEC CLUSTER SURVEY (HeCS) (2012, background): “Okabe & Umetsu (2008) used Subaru to analyze the lensing properties of A1758N and A1758S and found confirming evidence that both components are undergoing mergers.”
The Dark Matter Crisis: Falsification of the Current Standard Model of Cosmology (2012, background): “However, different groups analysing the same lensing data obtain different mass maps (see Okabe & Umetsu 2008).”