Day 819

Tuesday.

1501.04104
Bluk flows and end of the dark ages with the SKA
Maio, Ciardi, Koopmans

The early Universe is a probe of the birth of primordial objects, first SF events and consequent production of photons and heavy elements.  Higher-order corrections to the cosmological linear perturbation theory predicts the formation of coherent supersonic gases streaming motions at decoupling time.  These bulk flows impact the gas cooling process and determine a cascade effect on the whole baryon evolution.  By analytical estimates and N-body hydrodynamical chemistry numerical simulations including atomic an molecular evolution, gas cooling, SF, feedback  effects and metal spreading for individual species from different stellar populations according to the proper yields and lifetimes, discuss the role of these primordial bulk flows at the end of the dark ages and their detectable impacts during the first GYr in view of the upcoming SKA mission.  Early bulk flows can inhibit molecular gas cooling capabilities, suppressing SF, metal spreading and the abundance of small primordial galaxies in the infant Universe.  This can determine a delay in the re-ionization process and in the heating of neutral hydrogen making the observable HI signal during cosmic evolution patchier and noisier.  The planned SKA mission will represent a major advance over existing instruments, since it will be able to probe the effects on HI 21cm at z~6-20 and on molecular ling emissions from first collapsing sites at z~20-40.  Therefore, it will be optimal to address the effects of primordial streaming motions on early baryon evolution and to give constraints on structure formation in the first Gyr.

1501.04105
The bias of the submillimetre galaxy population: SMGs are poor tracers of the most massive structures n the z~2 universe
Miller, ... Behroozi et al

From Bolshoi cosmo sims, find that SMGs exhibit a relatively complex bias: some regions of high SMG overdensity are underdense in terms of DM mass, and some regions of high DM overdensity contain no SMGs.  Because of their rarity, Poisson noise causes scattering the SMG overdensity at fixed DM overdensity.  Consequently, rich associations of less-luminous, more-abundant galaxies (i.e., Lyman-break galaxy analogues) trace the highest DM over densities because of 'downsizing': at z<~2.5, the most-massive galaxies that reside in the highest DM over densities have already had their SF quenched and are thus no longer SMGs. Furthermore, because of Poisson noise and downsizing, some of the highest over densities are not associated with any SMGs.  Conversely, some bright SMGs are in underdense regions.