1302.3687
Confronting cold dark matter predictions with observed galaxy rotations
Obreschkow, et al
Galaxy rotation constrain galactic baryon physics and nature of DM. But comparing galaxy rotation with cosmo models is prone to subtle caveats. This analysis reveals full statistical consistency between 5k galaxy rotations, observed LoS projection, and predictions based on the standard LCDM at the mass-resolution of Millennium sim (HI line-based circular velocities above ~50 km/s). The HI linewidths in the HIPASS survey are found consistent with those in S3-SAX, a post-processed SAM for Millennium. Previously found anomalies in the VF can be plausibly attributed to (1) the mass-limit of the Millennium sim, (2) confused sources in HIPASS, (3) inaccurate inclination measurements for optically faint sources, and (4) the non-detectability of gas-poor early-type galaxies. These issues can be bypassed by comparing observations and models using linewidth source counts rather than VFs. Investigate if and how well such source counts can constrain the temperature of DM. [but no results given in abstract.]
1302.3825
The consequences of large Theta_13 for the turbulence signatures in supernova neutrinos
Kneller, Mauney
Set of transition probabilities for a single neutrino emitted from a pt src after passage through a turbulent SNe density profile have been found to be random variates drawn from parent distributions whose properties depend upon the stage of the explosion, the neutrino energy and mixing parameters, the observed channel, and the properties of the turbulence such as the amplitude C*. In this paper, examine the consequences of the recently meausured mixing angle theta_13 upon the neutrino flavor transformation in SNe when passing through turbulence. Find: measurements of a relatively large value of theta_13 means the neutrinos are relatively immune to small, C*<1%, amplitude turbulence, but as C* increases the turbulence effects grow rapidly and spread to all mixing channels. For C* > 10% the turbulence effects in the high density resonance mixing channels are independent of theta_13 but non-resonant mixing channels are more sensitive to turbulence when theta_13 is large.
1302.3243
The cosmic evolution of faint satellite galaxies as a test of galaxy formation and the nature of dark matter
Nierenberg, Treu, Menci, Lu, Wang
Show: cosmic evolution and host mass dependence of the satellite LF provides a powerful new diagnostic to disentangle astrophysical effects from variations in the underlying DM MF, for use of subhalo comparison between sim and observation. Illustrate with z=0.8 comparison of HST data with 3 SAM models of CDM and 1 SAM with WDM spectrum. Find: even though CDM models provide a reasonable fit to the local LF of satellites around galaxies comparable or slightly larger than the MW, they do not reproduce the data as well for different z and host galaxy stellar mass. This tension indicates that further improvements are likely to be needed in the description of SF if the models are to be reconciled with the data. The WDM model matches the observed mass dependence and z evolution of satellite galaxies more closely than any of the CDM models, indicating that a modification of the underlying PS may offer an alternative solution to this tension. Conclude by presenting predictions for the color magnitude relation of satellite galaxies to demonstrate how future observations will be able to further distinguish between these models and help constrain baryonic and non-baryonic physics.
1301.4220
A research note on the implementation of star formation and stellar feedback in semi-analytic models
Fontanot, ... Boylan-Kolchin et al
Study impact of SF and stellar feedback prescriptions on galaxy properties predicted by means of "stripped-down" versions of independent SAMs. These include cooling, SF, feedback from SNe, and simplified prescriptions for galaxy merging, but no chemical evolution, disc instabilities or AGN feedback.
1205.6906
The strongest gravitational lenses: I. the statistical impact of cluster mergers
Redlich, Bartelmann, Waizmann, Fedeli
Controversial: whether the high rate of giant gravitational arcs and the largest observed Einstein radii are consistent with the standard cosmological model. Indication: mergers provide an efficient mechanism to increase SL efficiency of individual clusters. Based on purely semi-analytic methods, investigate the statistical impact of cluster mergers on the distribution of the largest Einstein radii and the optical depth for gian gravitational arcs of selected cluster samples. Find: mergers increase the number of Einstein radii above 10" (20") by 35% (55%). Exploiting the tight correlation between Einstein radii and lensing cross sections, infer that the optical depth for giant gravitational arcs with length-to-width radio > 7.5 of those clusters with Einstein radii above 10" (20") increases by 45% (85%). Cluster mergers significantly influence the statistical lensing properties of the strongest gravitational lenses. Conclude that semi-analytic studies must inevitably take these events into account before questioning the standard cosmological model.
* merger increases Einstein radius, which increases number of arcs, based on SAM. that's that.
1205.5268
The gap closes: a new scenario for the evolution of supermassive black hole binaries with gaseous disks
Kocsis, Haiman, Loeb
SMBH binary and a standard radiatively efficient thin accretion disk. Steady-state configurations of the disk and migrating SMBH system, self-consistently accounting for tidal and viscous torques and heating
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