arXiv subjects

Carl Fields

Publications and source records attributed to Carl Fields.

3 recordsLinked to original sources

arXiv2026

AMReX-Astrophysics Microphysics: A set of microphysics routines for astrophysical simulation codes based on the AMReX library

The AMReX-Astrophysics Microphysics library provides a common set of microphysics routines (reaction networks and associated physics, equations of state, and various transport coefficients) as well as solvers (stiff ODE integrators, nonlinear system solvers) for astrophysical simulation codes built around the AMReX adaptive mesh refinement library (W. Zhang et al., 2019). Several multi-dimensional simulation codes, including the compressible hydrodynamics code Castro (Almgren et al., 2010), the low-Mach number hydrodynamics code MAESTROeX (Fan et al., 2019), and the radiation-hydrodynamics code Quokka (Wibking & Krumholz, 2022) use Microphysics to provide the physics and solvers needed to close the hydrodynamics systems that they evolve. The library is implemented in C++ with GPU-offloading a key design feature.

astro-ph.IM↗

arXiv2024

Phoebus: Performance Portable GRRMHD for Relativistic Astrophysics

We introduce the open source code PHOEBUS (phifty one ergs blows up a star) for astrophysical general relativistic radiation magnetohydrodynamic simulations. PHOEBUS is designed for, but not limited to, high energy astrophysical environments such as core-collapse supernovae, neutron star mergers, black-hole accretion disks, and similar phenomena. General relativistic magnetohydrodynamics are modeled in the Valencia formulation with conservative finite volume methods. Neutrino radiation transport is included with Monte Carlo and moment methods. PHOEBUS is built on the PARTHENON (Grete et al. 2022) performance portable adaptive mesh refinement framework, uses a GPU first development strategy, and is capable of modeling a large dynamic range in space and time. PHOEBUS utilizes KOKKOS for on-node parallelism and supports both CPU and GPU architectures. We describe the physical model employed in PHOEBUS, the numerical methods used, and demonstrate a suite of test problems to showcase its abilities. We demonstrate weak scaling to over 500 H100 GPUs.

astro-ph.HE↗

arXiv2019

Catching Element Formation In The Act

Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions.

astro-ph.HE↗