Day 1128

Wednesday.

1607.07881
How cosmic web detachment drive galaxy quenching
Aragon-Calvo, Neyrinck, Silk

Present the cosmic web detachment (CWD) model, a conceptual framework to interpret galaxy evolution in a cosmo context, providing a direct link between the star formation history of galaxies and the cosmic web.  The CWD model unifies several mechanism known to disrupt or stop SF into one single physical process and provides a natural explanation for a wide range of galaxy properties.  Galaxies begin accretion SF gas at early times via a network of primordial highly coherent filaments.  The efficient SF phase ends when NL interactions with other galaxies or elements of the cosmic web detach the galaxy from its network of primordial filaments, thus ending the efficient accretion of cold gas.  The stripping of the filamentary web around galaxies is the physics process responsible of SF quenching in gas stripping, harassment, strangulation and starvation.  Being a purely gravitational/mechanical process CWD acts at a more fundamental level than internal feedback processes.  Introduce a simple and efficient formalism to identify CWD events in N-body sims.  With it, reproduce and explain, in the context of CWD, several key observations including downsizing, the cosmic SFR history, the galaxy mass-color diagram and the dependence of the fraction of red galaxies with mass and local density.


1607.07910
Simultaneous constraints on cosmology and photometric redshift bias from weak lensing and galaxy clustering
Samuroff, Trowel, Bridle, Zuntz, MacCrann, Krause, Eifler, Kirk

Investigate the expected cosmo constraints from a combination of WL and LS galaxy clustering using realistic z distributions.  Introducing a systematic bias in the WL redshift distributions (of 0.05 in z) produces a >2 sigma bias in the recovered matter power spectrum amplitude and DE EoS, for preliminary Stage III surveys.  Demonstrate that these cosmological errors can be largely removed by marginalizing over unknown biases in the assumed WL redshift distributions, if we assume high quality z information for the galaxy clustering sample.  Furthermore the cosmo constraining power is mostly retained despite removing much of the information on the WL z distribution biases.  Show that this comes from complementary degeneracy directions between cosmic shear and the combination of galaxy clustering with cross-correlation between shear and galaxy number density.  Finally, examine how the self-calibration performs when the assumed distribution differ from the true distribution by more than a simple uniform bias.  Find that the effectiveness of this self-calibration method will depend on the details of a given experiment and the nature of the uncertainties on the estimated redshift distributions.