The Rise and Fall of Star-Forming Clumps: Formation and Evolution of the Building Blocks of Galaxies Across Cosmic Time
Bibliographic record
Abstract
It is well established that many high-redshift star-forming galaxies host massive, clumpy regions of intense star formation. However, the physical mechanisms responsible for clump formation remain uncertain, largely due to the lack of observations directly linking clump properties to their formation processes. In this dissertation, we investigate clump formation and evolution through three complementary studies. First, we test whether clump formation is associated with the accretion of metal-poor gas, which is expected to dilute a galaxy’s gas-phase metallicity. Using GNIRS spectroscopy from the Gemini-North telescope, we measure gas-phase metallicities for a small sample (<30) of clumpy and nonclumpy galaxies. We find that clumpy galaxies exhibit systematically lower metallicities relative to the mass–metallicity relation, consistent with clump formation driven by gas inflow. The second study uses resolved imaging from the James Webb Space Telescope CANUCS extragalactic fields to characterize clump populations and their mass distributions. We show that the slope of the aggregated clump mass function is consistent with clumps forming in-situ, but varies with host galaxy mass, becoming flatter in more massive systems and steeper in lower-mass galaxies. We also find that the clump mass function flattens with clump age, likely suggesting mechanisms effecting clump evolution. Finally, we combine spectroscopic and photometric data to extend our analysis to a larger sample of 300 star-forming galaxies. We find that clumpy galaxies with lower gas-phase metallicities tend to host younger, more actively star-forming clumps. Together, the results of this dissertation provide the first cohesive observational evidence linking gas accretion, clump formation, and clump evolution in high-redshift galaxies.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".