Photoionising feedback in spiral arm molecular clouds

Abstract

We present simulations of a 500 pc${}^2$ region, containing gas of mass 4 $\times$ 10${}^6$ M${}_{\odot }$, extracted from an entire spiral galaxy simulation, scaled up in resolution, including photoionising feedback from stars of mass > 18 M${}_{\odot }$. Our region is evolved for 10 Myr and shows clustered star formation along the arm generating $\approx$ 5000 cluster sink particles $\approx$ 5% of which contain at least one of the $\approx$ 4000 stars of mass > 18 M${}_{\odot }$. Photoionisation has a noticeable effect on the gas in the region, producing ionised cavities and leading to dense features at the edge of the HII regions. Compared to the no-feedback case, photoionisation produces a larger total mass of clouds and clumps, with around twice as many such objects, which are individually smaller and more broken up. After this we see a rapid decrease in the total mass in clouds and the number of clouds. Unlike studies of isolated clouds, our simulations follow the long range effects of ionisation, with some already-dense gas becoming compressed from multiple sides by neighbouring HII regions. This causes star formation that is both accelerated and partially displaced throughout the spiral arm with up to 30% of our cluster sink particle mass forming at distances > 5 pc from sites of sink formation in the absence of feedback. At later times, the star formation rate decreases to below that of the no-feedback case.

22 pages, 20 figures, accepted for publication in MNRAS

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Cited by in corpus (11)

• The formation of massive stellar clusters in converging galactic flows with photoionisation
• The growth of H II regions around massive stars: the role of metallicity and dust
• The formation of clusters and OB associations in different density spiral arm environments
• Stellar winds and photoionization in a spiral arm
• Far and extreme UV radiation feedback in molecular clouds and its influence on the mass and size of star clusters
• Mechanical feedback from stellar winds with an application to galaxy formation at high redshift
• The role of previous generations of stars in triggering star formation and driving gas dynamics
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