Primordial gravity waves from tidal imprints in large-scale structure

Abstract

I will describe a tidal effect whereby the decay of primordial gravity waves leaves a permanent shear in the large-scale structure of the Universe. Future large-scale structure surveys - especially radio surveys of high-redshift hydrogen gas - could measure this shear and its spatial dependence to form a map of the initial gravity-wave field. The three dimensional nature of this probe makes it sensitive to the helicity of the gravity waves, allowing for searches for early-Universe gravitational parity violation. Due to the large number of measurable modes in the high-redshift large-scale structure, these tidal imprints could ultimately be more sensitive than searches for CMB B-modes.