The Low-Redshift Lyman Continuum Survey II: New Insights into LyC
  Diagnostics
  The Lyman continuum (LyC) cannot be observed at the epoch of reionization (z
{\gtrsim} 6) due to intergalactic H I absorption. To identify Lyman continuum
emitters (LCEs) and infer the fraction of escaping LyC, astronomers have
developed various indirect diagnostics of LyC escape. Using measurements of the
LyC from the Low-redshift Lyman Continuum Survey (LzLCS), we present the first
statistical test of these diagnostics. While optical depth indicators based on
Ly{\alpha}, such as peak velocity separation and equivalent width, perform
well, we also find that other diagnostics, such as the [O III]/[O II] flux
ratio and star formation rate surface density, predict whether a galaxy is a
LCE. The relationship between these galaxy properties and the fraction of
escaping LyC flux suggests that LyC escape depends strongly on H I column
density, ionization parameter, and stellar feedback. We find LCEs occupy a
range of stellar masses, metallicities, star formation histories, and
ionization parameters, which may indicate episodic and/or different physical
causes of LyC escape.
