1711.09882
The shape of galaxy dark matter haloes in massive galaxy clusters: insights from strong gravitational lensing
Jauzac, Harvey, Massey
Assess how much unused strong lensing information is available in the deep HST imaging and VLT/MUSE spectroscopy of the Frontier Field clusters. As a pilot study, analyze galaxy cluster MACS J0416.1-2403 (z=0.397, M(R<200 kpc)=1.6e14 Msun), which has 141 multiple images with spectroscopic redshifts. Find that many additional parameters in a cluster mass model can be constrained, and that adding even small amounts of extra freedom to a model can dramatically improve its figures of merit. Use this information to constrain the distribution of DM around cluster member galaxies, simultaneously with the cluster's large-scale mass distribution. Find tentative evidence that some galaxies' dark matter has surprisingly similar ellipticity to their stars (unlike in the field, where it is more spherical), but that its orientation is often misaligned. When non-coincident DM and baryonic haloes are allowed, the model improves by 35%. This technique may provide a new way to investigate the processes and timescales on which DM is stripped from galaxies as they fall into a massive cluster. The preliminary conclusions will be made more robust by analyzing the remaining 5 Frontier Field clusters.
1711.10017
The effect of baryons in the cosmological lensing PDFs
Castro, et al
Understanding the effect of baryonic matter on the LSS is one of the challenges to be faced in cosmology. In this work, thoroughly study the effect of baryonic physics on different lensing statistics. Making use of the Magnetic Pathfinder suite of sims, show that on angular resolutions already achieved ongoing surveys the influence of luminous matter on the 1pt lensing statistics of point sources is significant, enhancing the probability of magnified objects with mu>3 by a factor of 2 and the occurrence of multiple-images by a factor of 6-30 depending on the source redshift. Also discuss the dependence of the lensing statistics on the angular resolution of surveys. The results and methodology were carefully tested in order to guarantee that the uncertainties are much smaller than the effects here presented.
1711.10018
Deriving galaxy cluster velocity anisotropy profiles from a joint analysis of dynamical and weak lensing data
Stark, Miller, Halenka
Present an analytic approach to lift the mass-anisotropy degeneracy in clusters of galaxies by utilizing the line-of-sight velocity dispersion of clustered galaxies jointly with WL-inferred masses. More specifically, solve the spherical Jeans equation by assuming a simple relation between the line-of-sight velocity dispersion and the radial velocity dispersion and recast the Jeans equation as a Bernoulli differential equation which has a well-known analytic solution. First test the method in cosmological N-body simulations and then derive the anisotropy profiles for 35 archival data galaxy with an average redshift of <z_c>=0.25. The resulting profiles yield a weighted average global value of <beta(0.2<=r/r200<=1)>=0.35±0.28(stat)±0.15(sys). This indicates that clustered galaxies tend to globally fall on radially anisotropic orbits. Note that this is the first attempt to derive velocity anisotropy profiles for a cluster sample of this size utilizing joint dynamical and WL data.
No comments:
Post a Comment