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We present new simulations of the flux power spectrum of the Lyman $\alpha$ forest as a means to investigate the effects of time-dependent dark energy on structure formation. We use a linearized parameterization of the time-dependence of the dark energy equation of state and sample the parameters ($w_0,w_a$) from the the extrema of the allowed observational values as determined by the Planck results. Each chosen ($w_0,w_a$) pair is then used in a high-resolution, large-scale cosmological simulation run with a modified version of the publicly available SPH code {\tt GADGET-2}. From each of these simulations we extract synthetic Lyman $\alpha$ forest spectra and calculate the flux power spectrum. We use the k-sample Anderson-Darling test to analyze the effects of dark energy on the Lyman $\alpha$ forest. We compare each dark energy power spectrum to that due to a cosmological constant power spectrum. We find, however, that there is only a marginal effect of the choice of allowed dark energy models on the flux power spectrum., Comment: 19 pages, 10 figures, 5 tables

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., Comment: 26 pages, 17 figures, submitted to MNRAS

We introduce a new self-consistent structure finding algorithm that parses large scale cosmological structure into clusters, filaments and voids. This structure finding algorithm probes the cosmological structure at multiple scales and clas- sifies the appropriate regions with the most probable structure type and size. We show that it reproduces key observational results, including the baryon fraction of ICM, and average temperatures and densities for the different structures., Comment: 17 pages, 5 figures