Towards a Unified Description of the Intergalactic Medium at Redshift
  z~2.5
  We examine recent measurements of the z~2.5 intergalactic medium (IGM) which
constrain the HI frequency distribution f(N) and the mean free path MFP to
ionizing radiation. We argue that line-blending and the clustering of strong
absorption-line systems have led previous authors to systematically
overestimate the effective Lyman limit opacity, yielding too small of a MFP for
the IGM. We further show that recently published measurements of f(N) at log
NHI ~ 16 lie in strong disagreement, implying underestimated uncertainty from
sample variance and/or systematics like line-saturation. Allowing for a larger
uncertainty in the f(N) measurements, we provide a new cubic Hermite spline
model for f(N) which reasonably satisfies all of the observational constraints
under the assumption of randomly distributed absorption systems. We caution,
however, that this formalism is invalid in light of absorber clustering and use
a toy model to estimate the effects. Future work must properly account for the
non-Poissonian nature of the IGM.
