Multi-Filament Inflows Fueling Young Star Forming Galaxies
  Theory suggests that there are two primary modes of accretion through which
dark matter halos acquire the gas to form and fuel galaxies, hot and cold mode
accretion. In cold mode accretion, gas streams along cosmic web filaments to
the center of the halo, allowing for the efficient delivery of star-forming
fuel. Recently, two QSO-illuminated HI Lyman alpha (Ly{\alpha}) emitting
objects were reported to have properties of cold, rotating structures (Martin
et al. 2015, Martin et al. 2016). However, the spatial and spectral resolution
available was insufficient to constrain radial flows associated with connecting
filaments. With the Keck Cosmic Web Imager (KCWI) we now have eight times the
spatial resolution, permitting the detection of these in-spiraling flows. In
order to detect these inflows, we introduce a suite of models which incorporate
zonal radial flows, demonstrate their performance on a numerical simulation
that exhibits coldflow accretion, and show that they are an excellent match to
KCWI velocity maps of two Ly{\alpha} emitters observed around high-redshift
quasars. These Multi-Filament Inflow models kinematically isolate zones of
radial inflow that correspond to extended filamentary emission. The derived gas
flux and inflow path is sufficient to fuel the inferred central galaxy star
formation rate and angular momentum. Thus, our kinematic emission maps provide
strong evidence for the inflow of gas from the cosmic web building galaxies at
the peak of star formation.
