Efficient adiabatic hydrodynamical simulations of the high-redshift intergalactic medium

Abstract

We present a post-processing tool for GADGET-2 adiabatic simulations to model various observed properties of the Ly$\alpha$ forest at $2.5\le z\le 4$ that enables an efficient parameter estimation. In particular, we model the thermal and ionization histories that are not computed self-consistently by default in GADGET-2. We capture the effect of pressure smoothing by running GADGET-2 at an elevated temperature floor and using an appropriate smoothing kernel. We validate our procedure by comparing different statistics derived from our method with those derived using self-consistent simulations with GADGET-3. These statistics are: line of sight density field power spectrum, flux probability distribution function, flux power spectrum, wavelet statistics, curvature statistics, HI column density (${\mathrm{N}}_{\mathrm{HI}}$) distribution function, linewidth ($b$) distribution and $b$ versus $\log {\mathrm{N}}_{\mathrm{HI}}$ scatter. For the temperature floor of $10^4$ K and typical signal-to-noise of 25, the results agree well within 20 percent of the self-consistent GADGET-3 simulation. However, this difference is smaller than the expected $1\sigma$ sample variance for an absorption path length of $\sim 5.35$ at $z=3$. Moreover for a given cosmology, we gain a factor of $\sim N$ in computing time for modelling the intergalactic medium under $N\gg 1$ different thermal histories. In addition, our method allows us to simulate the non-equilibrium evolution of thermal and ionization state of the gas and include heating due to non-standard sources like cosmic rays and high energy $\gamma$-rays from Blazars.

29 pages, 26 figures, 8 tables. New figures and tables are included, Accepted for publication in MNRAS

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Cited by in corpus (14)

• New synthesis models of consistent extragalactic background light over cosmic time
• Probing the thermal state of the intergalactic medium at $z>5$ with the transmission spikes in high-resolution Ly$\alpha$ forest spectra
• A consistent and robust measurement of the thermal state of the IGM at $2\le z\le 4$ from a large sample of Ly$\alpha$ forest spectra: Evidence for late and rapid HeII reionization
• Studying the Lyman-$\alpha$ optical depth fluctuations at $z\sim 5.5$ using fast semi-numerical methods
• Emission from the circumgalactic medium: from cosmological zoom-in simulations to multiwavelength observables
• Effect of non-equilibrium ionization on derived physical conditions of the high-$z$ intergalactic medium
• Probing the environment of high-z quasars using the proximity effect in projected quasar pairs
• Measuring the temperature and profiles of Lyman-$\alpha$ absorbers
• Three- and two-point spatial correlations of IGM at $z\sim 2$: Cloud based analysis using simulations
• Dark-Ages Reionisation & Galaxy Formation Simulation XVI: The Thermal Memory of Reionisation
• Lognormal semi-numerical simulations of the Lyman-$\alpha$ forest: comparison with full hydrodynamic simulations
• Physical conditions in high$-$z optically thin C III absorbers: Origin of cloud sizes and associated correlations
• Constraining the ratio of median pixel optical depth profile around z ~ 4 quasars using the longitudinal proximity effect
• Physical conditions and redshift evolution of optically thin C III absorbers: Low-z sample