Simulating Radiative Magnetohydrodynamical Flows with AstroBEAR: Implementation and Applications of Non-equilibrium Cooling

TL;DR

This paper introduces a new non-equilibrium cooling scheme integrated into the AstroBEAR MHD code, enabling accurate simulation of radiative shocks and synthetic emission maps for astrophysical jets and Herbig-Haro objects.

Contribution

The paper presents a novel non-equilibrium cooling implementation in AstroBEAR that accurately models ionization and emission in radiative MHD flows, validated against established shock codes.

Findings

AstroBEAR accurately predicts ionization and temperature in low-velocity radiative shocks.

The new routine enables synthetic emission maps for key atomic lines in stellar jets.

Validation shows good agreement with the Cox-Raymond shock code.

Abstract

Radiative cooling plays a crucial role in the dynamics of many astrophysical flows, and is particularly important in the dense shocked gas within Herbig-Haro (HH) objects and stellar jets. Simulating cooling processes accurately is necessary to compare numerical simulations with existing and planned observations of HH objects, such as those from the Hubble Space Telescope and the James Webb Space Telescope. In this paper we discuss a new, non-equilibrium cooling scheme we have implemented into the 3-D magnetohydrodynamic (MHD) code AstroBEAR. The new cooling function includes ionization, recombination, and excitation of all the important atomic species that cool below 10000 K. We tested the routine by comparing its predictions with those from the well-tested 1-D Cox-Raymond shock code (Raymond 1979). The results show thatAstroBEAR accurately tracks the ionization fraction, temperature, and other MHD variables for all low-velocity (.90 km/s) magnetized radiative shock waves. The new routine allows us to predict synthetic emission maps in all the bright forbidden and permitted lines observed in stellar jets, including H{\alpha}, [NII], [OI], and [SII]. We present an example as to how these synthetic maps facilitate a direct comparison with narrowband images of HH objects.