The robustness of cosmological hydrodynamic simulation predictions to changes in numerics and cooling physics

摘要: We test and improve the numerical schemes in our smoothed particle hydrodynamics (SPH) code for cosmological simulations, including pressure–entropy formulation (PESPH), a time-dependent artificial viscosity, refined time-step criterion, metal-line cooling that accounts photoionization presence of recently Haardt & Madau model ionizing background. The PESPH algorithm effectively removes surface tension present traditional SPH formulation, it produces better qualitative agreement with mesh-code results Kelvin–Helmholtz instability cold cloud disruption. Using set we examine many quantities have studied previous work. Results galaxy stellar H I mass functions, star formation histories, scaling relations, statistics Lyα forest are robust to changes numerics microphysics. As gas accretion dominates growth high-redshift galaxies low-mass at low redshift, recycling winds massive redshift. However, simulation spurious clumps seen earlier rate hot increases by up an order magnitude some redshifts. new also influences distribution metals among phases, leading considerable differences metal absorption lines, most notably Ne VIII.