Wednesday

The number densities of Lyman alpha emitters (LAEs) around L* drop very quickly above z=6, yet several examples of bright LAEs at z>7 suggest a different evolution at the bright end. One explanation is earlier reionization and higher Lyman alpha escape fractions in overdense regions. I will show that bright LAEs also have their detectability strongly enhanced by strong magnification bias from gravitational lensing by foreground galaxies, regardless of the high-z evolution of the luminosity function. The implication is that Euclid's 40 square degree imaging and grism spectroscopy survey will be extremely effective at probing bright ultra-high-redshift populations through strong lensing. These will be the brightest ultra-high-redshift line emitters known on the sky and wonderful JWST targets. I will also review the prospects of using similar magnification bias in CMB stage IV experiments, and the prospects of using SPICA follow-ups to track shock-heated molecular hydrogen lines at ultra-high-redshifts and the formation of the first organic molecules in the Universe.