Day 1060

Thursday.  Friday.  Monday.


1603.01276
Selection bias in dynamically-measured super-massive black hole samples: its consequences and the quest for the most fundamental relation
Shankar, Bernardi, Sheth, et al

Compare the set of local galaxies having dynamically measured BHs with a large, unbiased sample of galaxies extracted from the SDSS.  Confirm earlier work showing that majority of BH hosts have significantly higher velocity dispersions sigma than local galaxies of similar stellar mass.  Use MC sims to illustrate the effect on BH scaling relations if this bias arises from the requirement that the BH sphere of influence must be resolved to measure BH masses with spatially resolved kinematics.  Find that the selection effect artificially increases the normalization of the Mbh-sigma relation by a factor of at least ~3; the bias for the Mbh-Mstar relation is even larger.  The MC simulations and the analysis of the residuals from scaling relations both indicate that sigma is more fundamental than Mstar or effective radius.  The Mbh-Mstar relation is mostly a consequence of Mbh-sigma and sigma-star relations, and is heavily biased by up to a factor of 50 at small masses.  This helps resolve the discrepancy between dynamically-based BH-galaxy scaling relations versus those of active galaxies.  Sims also disfavor broad distributions of BH masses at fixed sigma.  Correcting for this bias suggests that the calibration factor used to estimate BH masses in active galaxies should be reduced to values of f_vir~1.  BH mass densities should also be proportionally smaller, perhaps implying significantly higher radiative efficiencies/BH spins.  Reducing BH masses also reduces the gravitational wave signal expected from BH mergers.


1603.01599
High resolution weak lensing mass-mapping combining shear and flexion
Lanusse, Starck, Leonard, Pires

Propose a new mass-mapping algorithm, specifically designed to recover small-scale information from a combination of gravitational shear and flexion.  Including flexion allows supplement on the shear on small scale in order to increase the sensitivity to substructures and the overall resolution of the convergence map without relying on strong lensing constraints.  In order to preserve all available small scale information, avoid any binning of the irregularly sampled input shear and flexion fields and treat the mass-mapping problem as a general ill-posed inverse problem, regularized using a robust multi-scale wavelet sparsity prior.  The resulting algorithm incorporates redshift, reduced shear, and reduced flexion measurements for individual galaxies and is made highly efficient by the use of fast Fourier estimators.  Test the reconstruction method on a set of realistic WL simulations corresponding to typical HST/ACS cluster observations and demonstrate the ability to recover substructures with the inclusion of flexion with are lost if only shear information is used .  In particular, can detect substructures at the 15" scale well outside of the critical region of the clusters.  In addition, flexion also helps to constrain the shape of the central regions of the main dark matter halos.  The mass-mapping software, called Glimpse2D, is made freely available at cosmostat.org.