Day 672

Friday.

1406.1170
On the density profile of dark matter substructure in gravitational lens galaxies
Vegetti, Vogelsberger

Consider 3 extensions of NFW profile and investigate the intrinsic degeneracies among the density profile parameters on the gravitational lensing effect of satellite galaxies on highly magnified Einstein rings.  In particular, find that the gravitational imaging technique can be used to exclude specific regions of the considered parameter space, and therefore, models that predict a large number of satellites in those regions.  By comparing the lensing degeneracy with the intrinsic density profile degeneracies, show that theoretical predictions based on fits that are dominated by the density profile at larger radii may significantly over- or underestimate the number of satellites that are detectable with gravitational lensing.  Finally, using the previously reported detection of a satellite in the gravitational lens system JVAS B1938+666 as an example, derive for this detected satellite values of r_max and v_max that are, for each considered profile, consistent within 1 sigma with the parameters found for the luminous dwarf satellite of the MW and with a mass density slope gamma < 1.6.  Also find that the mass of the satellite within the Einstein radius as measured using gravitational lensing is stable against assumptions on the substructure profile.  In the future thanks to the increased angular resolution of very long baseline interferometry at radio wavelengths and of the E-ELT in the optical, will be able to set tighter constraints on the number of allowed substructure profiles.

1406.1174
Halo mass and assembly history exposed in the faint outskirts: the stellar and dark matter haloes of Illustris galaxies
Pillepich, Vogelsberger, et al

Use Illustris Sims to gain insight into the build-up of the outer, low-surface brightness regions which surround galaxies.  Characterize the stellar haloes by means of the logarithmic slope of the spherically-averaged stellar density profiles, alphaSTARS at z=0, and relate these slopes to the properties of the underlying DM haloes, their central galaxies, and their assembly histories.  Analyze a sample of ~5000 galaxies resolved with more than 5e4 particles each, and spanning a variety of morphologies and halo masses (3e11<Mvir<1e14 Msun).  Find a strong trend between stellar halo slope and total halo mass, where more massive objects have shallower stellar haloes than the less massive ones (-5.5 pm 0.5<alphaSTARS<-3.5pm0.2 in the studied mass range).  At fixed halo mass, show that disk-like, blue, young, and more massive galaxies are surrounded by significantly steeper stellar haloes than elliptical, red, older, and less massive galaxies.  Overall, the stellar density profiles fall off much more steeply than the underlying DM, and no clear trend holds between stellar slope and DM halo concentration.  However, DM   than their older analogs with similar masses, by up to Delta(alphaSTARS)~0.5-0.7.  The findings, combined with the most recent measurements of the strikingly different stellar power-law indexes for M31 and the Milky Way, appear to favor a massive M31, and a MW characterized by a much quieter accretion history over the past 10 Gyrs than its companion.

1406.1379
An overview of the completed Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS)
Hidebrandt, for CFHTLenS Collaboration

Review the technical challenges faced in analyzing the data and their solutions; present science highlights made possible bye this effort including cosmic shear tomography, tests for modified gravity models, and the mapping for DM structures over unprecedentedly large scales.  An outlook is given on current and future surveys that are analyzed with the tools used in CFHTLenS.