Аннотация
We investigate the spatially-resolved star formation relation using a
galactic disk formed in a comprehensive high-resolution (3.8 pc) simulation.
Our new implementation of stellar feedback includes ionizing radiation as well
as supernova explosions, and we handle ionizing radiation by solving the
radiative transfer equation rather than by a subgrid model. Photoheating by
stellar radiation stabilizes gas against Jeans fragmentation, reducing the star
formation rate. Because we have self-consistently calculated the location of
ionized gas, we for the first time are able to make spatially-resolved mock
observations of star formation tracers, such as H-alpha emission. We can also
observe how stellar feedback manifests itself in the correlation between
ionized and molecular gas. Applying our techniques to the disk in a galactic
halo of 2.3e11 Msun, we find that the correlation between star formation rate
density (estimated from mock H-alpha emission) and molecular hydrogen density
shows large scatter, especially at high resolutions of <~ 75 pc that are
comparable to the size of giant molecular clouds (GMCs). This is because an
aperture of GMC size captures only particular stages of GMC evolution. By
examining the evolving environment around star clusters, we demonstrate that
the breakdown of the traditional star formation laws of the Kennicutt-Schmidt
type at small scales results from a combination of stars drifting from their
birthplaces, and molecular clouds being dispersed via ionizing radiation and
supernova feedback.
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