The natural emergence of the correlation between $H_2$ and star formation rate surface densities in galaxy simulations
Résumé
In this study, we present a suite of high-resolution numerical simulations of an isolated galaxy to test a sub-grid framework to consistently follow the formation and dissociation of H_2 with non-equilibrium chemistry. The latter is solved via the package krome, coupled to the mesh-less hydrodynamic code gizmo. We include the effect of star formation (SF), modelled with a physically motivated prescription independent of H_2, supernova feedback and mass-losses from low-mass stars, extragalactic and local stellar radiation, and dust and H_2 shielding, to investigate the emergence of the observed correlation between H_2 and SF rate surface densities. We present two different sub-grid models and compare them with on-the-fly radiative transfer (RT) calculations, to assess the main differences and limits of the different approaches. We also discuss a sub-grid clumping factor model to enhance the H_2 formation, consistent with our SF prescription, which is crucial, at the achieved resolution, to reproduce the correlation with H_2. We find that both sub-grid models perform very well relative to the RT simulation, giving comparable results, with moderate differences, but at much lower computational cost. We also find that, while the Kennicutt–Schmidt relation for the total gas is not strongly affected by the different ingredients included in the simulations, the H_2-based counterpart is much more sensitive, because of the crucial role played by the dissociating radiative flux and the gas shielding.
Domaines
Astrophysique [astro-ph]Origine | Fichiers éditeurs autorisés sur une archive ouverte |
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