How the Cookie Crumbles: A Model for Star-forming Clumps in High-redshift Disk Galaxies
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| Format: | Preprint |
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2024
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| author | Orr, Matthew E. Rennehan, Douglas |
| author_facet | Orr, Matthew E. Rennehan, Douglas |
| contents | We present a simple model for the number distribution of maximally star-forming clumps in rotating disk galaxies, at high-$z$ with high gas surface densities. By combining assumptions surrounding marginal stability of disks against gravitational fragmentation and collapse (i.e., Toomre's $Q\approx 1$), star cluster formation efficiency scaling with local gas surface density, and star formation rates being tied to the relevant local dynamical/free-fall times, we find a star-forming clump distribution of $N_c(> \dot M_\star) \propto \dot M_\star^{-4/3}$ when assuming a power-law form for the gas surface density profile, and a numerically integrable relation for arbitrary gas disk profiles. We compare this model with recent high-redshift observations of lensed clumpy star-forming rotation-dominated galaxies, and find good agreement with the distribution of clump star formation rates and number of clumps. Moreover, we argue that any rotation-supported galaxy should have a significantly higher number of identifiable star-forming clumps relative to dispersion supported objects at a similar mass as $N_c \sim (V_c/σ)^2$. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2410_23337 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | How the Cookie Crumbles: A Model for Star-forming Clumps in High-redshift Disk Galaxies Orr, Matthew E. Rennehan, Douglas Astrophysics of Galaxies We present a simple model for the number distribution of maximally star-forming clumps in rotating disk galaxies, at high-$z$ with high gas surface densities. By combining assumptions surrounding marginal stability of disks against gravitational fragmentation and collapse (i.e., Toomre's $Q\approx 1$), star cluster formation efficiency scaling with local gas surface density, and star formation rates being tied to the relevant local dynamical/free-fall times, we find a star-forming clump distribution of $N_c(> \dot M_\star) \propto \dot M_\star^{-4/3}$ when assuming a power-law form for the gas surface density profile, and a numerically integrable relation for arbitrary gas disk profiles. We compare this model with recent high-redshift observations of lensed clumpy star-forming rotation-dominated galaxies, and find good agreement with the distribution of clump star formation rates and number of clumps. Moreover, we argue that any rotation-supported galaxy should have a significantly higher number of identifiable star-forming clumps relative to dispersion supported objects at a similar mass as $N_c \sim (V_c/σ)^2$. |
| title | How the Cookie Crumbles: A Model for Star-forming Clumps in High-redshift Disk Galaxies |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2410.23337 |