Day 1013

Monday after Thanksgiving.


1511.08211
MultiDarkLens Simulations: weak lensing light-cones and data base presentation
Giocoli, Jullo, Metcalf, et al

Present a large database of WL light cones constructed using different snapshots of the Big MultiDark sim (BigMDPL).  The ray-tracing through different multiple planes has been performed with the GLAMER code accounting both for single source redshifts and for sources distributed along the cosmic time.  This first paper presents WL forecasts and results according to the geometry of the VIPERS-W1and W4 field of view.  Additional fields will be available on the database and new ones can be run upon request.  The database also contains some tools for lensing analysis.  In this paper, present results for convergence power spectra, one point and high order WL statistics useful for forecasts and for cosmo studies.  Covariance matrices have also been computed for the different realizations of the W1 and W4 fields.  In addition compute also galaxy-shear and projected density contrasts for different halo masses at two lens redshifts according to the CFHTLS source redshift distribution both using stacking and cross-correlation techniques, finding very good agreement.


1511.08212
The lifecycle of clusters in galaxies
Adamo, Bastian

Review basic properties of star cluster systems, and how they relate to their host galaxy properties and ambient environment.  Custer mass and LFs well approximated by power laws with alpha~-2 over most of the observable range.  Both become steeper at high masses/luminosities, with the value of the downward turn dependent on environment.  The host galaxy properties also appear to affect the cluster formation efficiency (Gamma - i.e., the fraction of stars that form in bound clusters), with higher star-formation rate density galaxies having higher Gamma values.  Within individual galaxies, there is evidence for Gamma to vary by a factor of 3-4, likely following the molecular gas surface density, in agreement with recent predictions.  Finally, discuss cluster disruption and its effect on the observed properties of a population, focussing on the age distribution of clusters.  Briefly discuss the expectations of theoretical and numerical studies, and also the observed distributions in a number of galaxies.  Most observational studies now find agreement with theoretical expectations, namely nearly a constant cluster age distribution for ages up to ~100 Myr (i.e., little disruption), and a drastic steepening above this value caused by a combination of cluster disruption and incompleteness.  Rapid cluster disruption for clusters with ages <100 Myr is ruled out for most galaxies.


1511.08311
The Megamaser Cosmology project VIII.  A geometric distance to NGC 5765b
Gao, et al

Present a new geometric distance measurement to the megamaser galaxy NGC 5765b.  Confirmed the water masers trace a thin, sub parsec Keplerian disk around the nucleus, implying an enclosed mass of 4.55±0.40e7 Msun.  Meanwhile, from observations over 2 years, measure the secular drifts of maser features near the systemic velocity of the galaxy with rates between 0.5 and 1.2 km/s/yr.  Fitting a warped, thin disk model to these measurements, determine a Hubble constant H0 of 66.0±6.0 km/s/Mpc with the angular-diameter distance to 126.3±11.6 Mpc.  Apart from the distance measurement, also investigate some physical properties related to the maser disk in the galaxy.  The high-velocity features are spatially distributed into several clumps, which may indicate the existence of a spiral density wave associated with the accretion disk. For the red-shifted features, the envelope defined by the peak maser intensities increases with radius.  The profile of the systemic masers in the galaxy is smooth and shows almost no structural changes over the 2 years of monitoring time, which differs form the more variable case of NGC 4258.


1511.08502
How big can a black hole grow?
King

Show that there is a physical limit to the mass of a BH, above which it cannot grow through luminous accretion of gas, and so cannot appear as a quasar or AGN.  The limit is M_max~5e10 Msun for typically parameters, but can reach 2.7e11 Msun in extreme cases (maximal prograde spin).  The largest BH masses so far found are close but below the limit.  The Eddington luminosity ~ 6.5e48 erg/s corresponding to Mmax is remarkable close to the largest AGN bolometric luminosity so far observed.  The mass and luminosity limits both rely on a reasonable but currently untestable hypothesis about AGN disk formation, so future observations of extreme SMBH masses can therefore probe fundamental disc physics.  BHs can in principle glow their masses above Mmax by non-luminous means such as mergers with other holes, but cannot become luminous accretions again.  They might nevertheless be detectable in other ways, for example through gravitational lensing.  Show further that BHs with masses~Mmax can probably grow above the values specified by the BH -- host-galaxy scaling relations, in a agreement with observation.