The Agora High-Resolution Galaxy Simulations Comparison Project

Abstract

We introduce the AGORA project, a comprehensive numerical study of well-resolved galaxies within the ΛCDM cosmology. Cosmological hydrodynamic simulations with force resolutions of ∼ 100 proper pc or better will be run with a variety of code platforms to follow the hierarchical growth, star formation history, morphological transformation, and the cycle of baryons in and out of 8 galaxies with halo masses M vir ≃ 10 10 , 10 11 , 10 12 , and 10 13 M ⊙ at z = 0 and two different ("violent" and "quiescent") assembly histories. The numerical techniques and implementations used in this project include the smoothed particle hydrodynamics codes GADGET and GASOLINE, and the adaptive mesh refinement codes ART, ENZO, and RAMSES. The codes will share common initial conditions and common astrophysics packages including UV background, metaldependent radiative cooling, metal and energy yields of supernovae, and stellar initial mass function. These are described in detail in the present paper. Subgrid star formation and feedback prescriptions will be tuned to provide a realistic interstellar and circumgalactic medium using a non-cosmological disk galaxy simulation. Cosmological runs will be systematically compared with each other using a common analysis toolkit, and validated against observations to verify that the solutions are robust -i.e., that the astrophysical assumptions are responsible for any success, rather than artifacts of particular implementations. The goals of the AGORA project are, broadly speaking, to raise the realism and predictive power of galaxy simulations and the understanding of the feedback processes that regulate galaxy "metabolism." The initial conditions for the AGORA galaxies as well as simulation outputs at various epochs will be made publicly available to the community. The proof-ofconcept dark matter-only test of the formation of a galactic halo with a z = 0 mass of M vir ≃ 1.7 × 10 11 M ⊙ by 9 different versions of the participating codes is also presented to validate the infrastructure of the project. The project website is http://www.AGORAsimulations.org/. Need for High-Resolution Galaxy SimulationAs the above discussion should make clear, the success of cosmological galaxy formation simulations in producing real- 30 The force softening of the Aquila GASOLINE simulation was 460 proper pc from z = 9 to z = 0, and the mass per dark matter and gas particle was 2.1 and 0.5 × 10 6 M ⊙ , respectively. The Eris simulation had the force softening of 120 proper pc from z = 9 to z = 0, and better mass per dark matter and gas particle of 9.8 and 2.0 × 10 4 M ⊙ , respectively.

Dusty star-forming galaxies at high redshift

“…The uncertainty, of course, is whether locally-calibrated observational templates are applicable to galaxies at the same luminosity at high-z. A recent example of this sort of application of observed SED templates to SAMs is presented in Somerville et al (2012); Kim et al (2014).…”

“…A number of code comparison projects have been performed, and are currently underway (e.g. Scannapieco et al, 2012;Kim et al, 2014).…”

GMC Collisions as Triggers of Star Formation. II. 3D Turbulent, Magnetized Simulations

“…The resulting heating and cooling rates are incorporated into Enzo via the Grackle external chemistry and cooling library 7 (Bryan et al 2014;Kim et al 2014). The information is read in via the purely tabulated method and modifies the gas internal energy,…”

“…Software: Enzo (Bryan et al 2014), Grackle (Bryan et al 2014;Kim et al 2014), PyPDR, and yt (Turk et al 2011).…”

Tracing the Evolution of High-Redshift Galaxies Using Stellar Abundances

“…In Equation (5), the first term represents gas that cools from the reservoir and condenses into the central region, and τ cool is the cooling time of the gas, which is calculated using the Grackle chemistry and cooling library 10 (Bryan et al 2014;Kim et al 2014). The second term represents gas ejected from the SNe in the central region that enters the reservoir, where Δt is the integration timestep and Λ is a factor encapsulating information about the SNe that occurred during this integration time step (see Equation (11) in Section 2.4).…”