Day 1274

Tuesday.  Wednesday.


1706.06125
The galaxy-subhalo connection in low-redshift galaxy clusters from weak gravitational lensing
Sifón, et al

Measure the gravitational lensing signal around satellite galaxies in a sample of galaxy clusters at z<0.15 by combining high-quality imaging data from CFHT with a large sample of spectroscopically-confirmed cluster members.  Use extensive image sims to assess the accuracy of shape measurements of faint, background sources in the vicinity of bright satellite galaxies.  Find a small but significant bias, as light from the lenses makes the shapes of background galaxies appear radially aligned with the lens.  Account for this bias by applying a correction that depends on both lens size and magnitude.  Also correct for contamination of the source sample by cluster members.  Use a physically-motivated definition of sub halo mass, namely the mass bound to the sub halo, m_bg, similar to definitions used by common sub halo finders in numerical sims.  Binning the satellites by stellar mass, provide a direct measurement of the subhalo-to-stellar-mass relation, log m_bg/Msun=(11.66±0.07)+(0.94±0.15) log [m*/(2e10Msun)].  This best-fitting relation implies that, at a stellar mass m*~3e10 Msun, sub halo masses are roughly 50% lower than their central counterparts, and this fraction decreases at higher stellar masses.  On the other hand, find no statistically significant evidence for mass segregation when lenses are binned by their projected cluster-centric distance, contrary to recent claims, with an average total-to-stellar mass ratio <m_bg/m*>=21.5+6.3-5.5.  Find that, once the projected effects and for differences between DM sub haloes and satellite galaxies are accounted for, the results are consistent with theoretical predictions.