Day 555

Thursday.

1311.6473
Central galaxies in different environments: do they have similar properties?
Lacerna et al

Perform exhaustive comparison among central galaxies from SDSS catalogs in different local environments at 0.01<=z<=0.08.  The central galaxies are separated into two categories: group centrals (host halos containing satellites) and field centrals (host halos without satellites).  From the latter, select other two subsamples: isolated centrals and bright field centrals, both with the same magnitude limit.  The stellar mass (Ms) distributions of the field and group central galaxies are different, which explain why in general the field central galaxies are located in the blue cloud/SF regions, where as the group central galaxies are in the red sequence/ passive regions.  The isolated centrals occupy the same regions as the bright field centrals since both populations have similar Ms distributions.  At parity [?] of Ms, the color and sSFR distributions of the samples are similar, especially between field and group centrals.  Furthermore, find that the stellar-to-halo mass (Ms/Mh) relation of isolated galaxies does not depend on the color, sSFR and morphological type.  For systems without satellites, the Ms-Mh relation steep ends at high Mh compared to group centrals, which is explained as a condition of the Ms distribution inside the halo.  The scatter around the Ms-Mh relation of systems without satellites is <0.08 dex and roughly constant with Mh, in contrast to the scatter for group centrals which is >0.1 dex and increasing with Mh.  Results suggest that the mass growth of central galaxies is mostly driven by the halo mass.

1311.6523
First galaxy-galaxy lensing measurement of satellite halo mass in the CFHT/MegaCam stripe-82 survey
Li, … Kneib, … van den Bosch, Erbein, … et al

Measure the tangential shear around satellite galaxies, fit to truncated NFW, find mass.  [Not a very significant detection.]

1311.7035
How well do third-order aperture mass statistics separate E- and B-modes?
Shi, Joachimi, Schneider

It has been demonstrated that 2nd order aperture mass statistics suffer from E-/B-mode mixing because it is impossible to reliably estimate the shapes of close pairs of galaxies.  This finding has triggered developments of several new 2nd-order statistical measures for cosmic shear.  Whether the same developments are needed for 3rd-order shear statistics is largely determined by how severe this E-/B-mixing is for 3rd-order statistics.  Test 3rd-order aperture mass statistics against E-/B-mode mixing, and find that the level of contamination is well described by a function of theta/theta_min, with theta_min being the cut-off scale.  At angular scales of theta>10 theta_min, the decrease in the E-mode signal due to E-/B-mode mixing is smaller than 1 percent, and the leakage into B-modes is even less.  For typical small-scale cut-offs this E-/B-mixing is negligible on scales larger than a few arc minutes.  Therefore, 3rd-order aperture mass statistics can safely be used to separate E- and B-modes and infer cosmological information, for ground-based surveys as well as forthcoming space-based surveys such as Euclid.

1311.7036
Testing cosmological models with the brightness profile of distant galaxies
Olivares-Salaverri, Ribeiro

Use observed galaxy surface brightness profiles at high redshifts to determine the cosmological model based suited to interpret these observations.  Theoretical predictions of galactic surface brightness profiles are compared to observational data in two cosmological models, LCDM and Einstein-de Sitter, to calculate the evolutionary effects of different space-time geometries in these profiles in order to try to find out if the available data is capable of indicating the cosmology that best represents actual galactic brightness profiles observations.  Starting from the connection between the angular diameter distance and the galactic surface brightness as advanced by Ellis hand Perry, derive scaling relations using data from the Virgo galactic cluster in order to obtain theoretical predictions of the galactic surface brightness modeled by the Sersic profile at redshift values equal to a sample of galaxies in the range 1.5<z<2.3 composed by a subset of Szomoru+ 2012 observations.  Then calculate the difference between theory and observation in order to determine the changes required in the effective radius and effective surface brightness so that the observed galaxies may evolve to have features similar to the Virgo cluster ones.  Results show that within the data uncertainties of this particular subset of galaxies it is not possible to distinguish which of the two cosmological models used here predicts theoretical curves in better agreement with the observed ones, that is, one cannot identify a clear and detectable difference in galactic evolution incurred by the galaxies of the sample when applying each cosmology.  Conclude that the Sersic index n does not seem to play a significant effect in the evolution of these galaxies.