The Physical Origins of the Identified and Still Missing Components of
  the Warm-Hot Intergalactic Medium: Insights from Deep Surveys in the Field of
  Blazar 1ES1553+113
  The relationship between galaxies and the state/chemical enrichment of the
warm-hot intergalactic medium (WHIM) expected to dominate the baryon budget at
low-z provides sensitive constraints on structure formation and galaxy
evolution models. We present a deep redshift survey in the field of
1ES1553+113, a blazar with a unique combination of UV+X-ray spectra for surveys
of the circum-/intergalactic medium (CGM/IGM). Nicastro et al. 2018 reported
the detection of two O VII WHIM absorbers at $z=0.4339$ and $0.3551$ in its
spectrum, suggesting that the WHIM is metal-rich and sufficient to close the
missing baryons problem. Our survey indicates that the blazar is a member of a
$z=0.433$ group and that the higher-$z$ O VII candidate arises from its
intragroup medium. The resulting bias precludes its use in baryon censuses. The
$z=0.3551$ candidate occurs in an isolated environment 630 kpc from the nearest
galaxy (with stellar mass $\log M_*/M_\odot \approx 9.7$) which we show is
unexpected for the WHIM. Finally, we characterize the galactic environments of
broad H I Ly$\alpha$ absorbers (Doppler widths of $b=40-80$ \kms;
$T\lesssim4\times10^5$ K) which provide metallicity independent WHIM probes. On
average, broad Ly$\alpha$, absorbers are ${\approx}2\times$ closer to the
nearest luminous ($L>0.25 L_*$) galaxy (700 kpc) than narrow ($b<30$ \kms;
$T\lesssim4\times10^5$ K) ones (1300 kpc) but ${\approx}2\times$ further than
O\,VI absorbers (350 kpc). These observations suggest that gravitational
collapse heats portions of the IGM to form the WHIM but with feedback that does
not enrich the IGM far beyond galaxy/group halos to levels currently observable
in UV/X-ray metal lines.
