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 Plus annual

Presents the access of premium content as premium feature

Premium Content

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 annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We study the ellipticity of galaxy cluster halos as characterized by thedistribution of cluster galaxies and as measured with weak lensing. We usemonte-carlo simulations of elliptical cluster density profiles to estimate andcorrect for Poisson noise bias, edge bias and projection effects. We apply ourmethodology to 10,428 SDSS clusters identified by the redMaPPer algorithm withrichness above 20. We find a mean ellipticity $= 0.271 \pm 0.002$ (stat) $\pm0.031$ (sys) corresponding to an axis ratio $= 0.573 \pm 0.002$ (stat) $\pm0.039$ (sys). We compare this ellipticity of the satellites to the halo shape,through a stacked lensing measurement using optimal estimators of the lensingquadrupole based on Clampitt and Jain (2016). We find a best-fit axis ratio of$0.56 \pm 0.09$ (stat) $\pm 0.03$ (sys), consistent with the ellipticity of thesatellite distribution. Thus cluster galaxies trace the shape of the darkmatter halo to within our estimated uncertainties. Finally, we restack thesatellite and lensing ellipticity measurements along the major axis of thecluster central galaxy's light distribution. From the lensing measurements weinfer a misalignment angle with an RMS of ${30^\circ \pm 10}^\circ$ whenstacking on the central galaxy. We discuss applications of halo shapemeasurements to test the effects of the baryonic gas and AGN feedback, as wellas dark matter and gravity. The major improvements in signal-to-noise expectedwith the ongoing Dark Energy Survey and future surveys from LSST, Euclid andWFIRST will make halo shapes a useful probe of these effects.

The ellipticity of galaxy cluster halos from satellite galaxies and weak lensing