Day 768

Tuesday.

1410.4937
Galaxy stellar mass assembly: the difficulty to match observations and semi-analytical predictions
Cousin, et al

SAMs are currently the best way to understand the formation of galaxies within the cosmic DM structures.  While they fairly well reproduce the local stellar MFs, correlation functions and LFs, they fail to match observations at high z (>3) in most cases, particularly in the low-mass range.  The inconsistency between models and observations indicates that the history of gas accretion in galaxies, within their host DM halo, and the transformation of gas into stars, are not well followed.  Briefly present a new version of the GalICS SAM. Explore the impacts of classical mechanisms, such as SNe feedback or photoionization, on the evolution of the stellar mass assembly.  Even with a strong efficiency, these two processes cannot explain the observed stellar MF and SFR distribution and some other relations.  Thus introduce an ad-hoc modification of the standard paradigm, based on the presence of a no-SF gas component, and a concentration of the SF gas in galaxy disks.  The main idea behind the existence of the no-SF gas reservoir is that only a fraction of the total gas mass in a galaxy is available to form stars.  The reservoir generates a delay between the accretion of the gas and the SF process.  This new model is in much better agreement with the observations of the stellar MF in the low-mass range than the previous models, and agrees quite well with a large set of observations, including the z evolution of the sSFR.  However, it predicts a large fraction of no-SF baryonic gas, potentially larger than observed, even if its nature has still to be examined in the context of the missing baryon problem.

1410.4997
Evidence of cross-correlation between the CMB lensing and the gamma-ray sky
Fornengo et al

3.2 sigma, in correlation with Planck CMB lensing map.