Star Formation and Gas Phase History of the Cosmic Web
  We present a new method of tracking and characterizing the environment in
which galaxies and their associated circumgalactic medium evolve. We use a
structure finding algorithm we developed to self-consistently parse and follow
the evolution of poor clusters, filaments and voids in large scale simulations.
We trace the complete evolution of the baryons in the gas phase and the star
formation history within each structure in our simulated volume. We vary the
structure measure threshold to probe the complex inner structure of star
forming regions in poor clusters, filaments and voids. We find the majority of
star formation occurs in cold, condensed gas in filaments at intermediate
redshifts (z ~ 3). We also show that much of the star formation above a
redshift z = 3 occurs in low contrast regions of filaments, but as the density
contrast increases at lower redshift star formation switches to the high
contrast regions, or inner parts, of filaments. Since filaments bridge the void
and cluster regions, it suggests that the majority of star formation occurs in
galaxies in intermediate density regions prior to the accretion onto poor
clusters. We find that at the present epoch, the gas phase distribution is
43.1%, 30.0%, 24.7% and 2.2% in the diffuse, WHIM, hot halo and condensed
phases, respectively. The majority of the WHIM is associated with filaments.
However, their multiphase nature and the fact that the star formation occurs
predominantly in the condensed gas both point to the importance of not
conflating the filamentary environment with the WHIM. Moreover, in our
simulation volume 8.77%, 79.1%, 2.11% of the gas at z = 0 is located in poor
clusters, filaments, and voids, respectively. We find that both filaments and
poor clusters are multiphase environments distinguishing themselves by
different distribution of gas phases.
