Day 786

Friday.

1411.3330
Cosmic dawn: studies of the earliest galaxies and their role in cosmic reionization
Ellis

Recent progress and challenges of the earliest galaxies, when the Universe was <1Byr old.  Can they be used as reliable traces of the physics of cosmic reionizaton thereby complementing other, more direct, probes of the evolving neutrality of the IGM?  Were SF galaxies the primary agent in the reionization process and what are the future prospects for identifying the earliest systems devoid of chemical enrichment?  Ambitious future facilities are under construction of exploring galaxies and the IGM in 6<z<20, corresponding to what is considered the heart of the reionization era.  Review that can be inferred about this period from current observations and in the near future with existing facilities, and conclude with a list of key issues where future work is required.

1411.3333
Dust in the circumgalactic medium of low-reshift galaxies
Peek, Ménard, Corrales

Using spectroscopically selected galaxies from SDSS, present a detection of reddening due to dust in the circumgalactic medium of galaxies.  Detect the mean change in the colors of "standard crayons" correlated with the presence of FG galaxies at z~0.05 as a function of angular separation.  Following Peek&Graves(2010), create standard crayons using passively evolving galaxies corrected for MW reddening and color-redshift trends, leading to a sample with as little as 2% scatter in color.  Devise methods to ameliorate possible systematic effects related to the estimation of colors, and find an excess reddening induced by FG galaxies at a level ranging from 10 to 0.5 mmags on scales ranging from 30 kpc to 1 Mpc.  Attribute this effect to a large-scale distribution of dust around galaxies similar to the findings of Menard+2010.  Find that circumgalactic reddening is a weak function of stellar mass over the range 6e9Msun-6e10Msun and note that this behavior appears to be consistent with recent results on the distribution of metals in the gas phase.