STARBENCH: the D-type expansion of an HII region

Bisbas, T G, Haworth, T J, Williams, R J R, Mackey, J, Tremblin, P, Raga, A C, Arthur, S J, Baczynski, C, Dale, J E, Frostholm, T, Iliev, I T, Sullivan, D, et al, and Unset (2015) STARBENCH: the D-type expansion of an HII region. Monthly Notices of the Royal Astronomical Society, 453 (2). pp. 1324-1343. ISSN 0035-8711

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STARBENCH is a project focused on benchmarking and validating different star formation and stellar feedback codes. In this first STARBENCH paper we perform a comparison study of the D-type expansion of an H II region. The aim of this work is to understand the differences observed between the 12 participating numerical codes against the various analytical expressions examining the D-type phase of H II region expansion. To do this, we propose two well-defined tests which are tackled by 1D and 3D grid- and smoothed particle hydrodynamics-based codes. The first test examines the ‘early phase’ D-type scenario during which the mechanical pressure driving the expansion is significantly larger than the thermal pressure of the neutral medium. The second test examines the ‘late phase’ D-type scenario during which the system relaxes to pressure equilibrium with the external medium. Although they are mutually in excellent agreement, all 12 participating codes follow a modified expansion law that deviates significantly from the classical Spitzer solution in both scenarios. We present a semi-empirical formula combining the two different solutions appropriate to both early and late phases that agrees with high-resolution simulations to ≲ 2 per cent. This formula provides a much better benchmark solution for code validation than the Spitzer solution. The present comparison has validated the participating codes and through this project we provide a data set for calibrating the treatment of ionizing radiation hydrodynamics codes.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Astronomy Centre
Subjects: Q Science > QB Astronomy
Depositing User: Billy Wichaidit
Date Deposited: 06 Jul 2017 13:10
Last Modified: 06 Jul 2017 13:16

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