English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We report on the detection of dark matter in the cluster of galaxiesAbell~2163 using the weak gravitational distortion of background galaxies, andan analysis of the cluster X-ray emission. We find that while the qualitativedistributions of the cluster light and the dark matter are similar -- shallowand extended, with significant substructure -- the X-ray morphology shows amore regular overall appearance. We interpret the joint lensing and X-rayobservations as a signature of a merger event in the cluster. We present newROSAT/HRI data and reanalyze ROSAT/PSPC data, accounting for the effect of avarying background to determine the best fit parameters in the $\beta$-modelformalism. We combine the surface brightness fits with two determinations ofthe radial temperature profile to determine the total mass. Although there areslight variations in the total mass determinations introduced by theuncertainties in the $\beta$-fit, the main contributor to the error arises fromthe uncertainties in the temperature determinations. Even though themorphologies of the dark matter/light and X-ray gas are quite different, wefind that the total mass determined from the X-ray and weak lensing estimatesare consistent with each other within the $2\sigma$ error bars, with the X-rayinferred mass a factor of $\simeq 2$ larger. However, as the lensing massestimates are differential (the surface density at any point is determinedrelative to the mean in a control annulus), the shallow, extended nature of themass profile biases the lensing inferred mass downwards. We estimate thecorrection for this effect and find very good agreement between the correctedlensing and X-ray results. We determine the gas mass fraction and find $f_g\simeq 0.07h^{-3/2}$ at all radii and a constant mass-to-light ratio of $M/L_VComment: 30 pages, latex file. Postscript file also available at  ftp://magicbean.berkeley.edu/pub/squires/a2163/a2163_paper.ps.g

Weak Gravitational Lensing and X‐Ray Analysis of Abell 2163