The earliest stars and their relics in the Milky Way
Bibliographic record
Abstract
We have implemented a simple model to identify the likely sites of the first stars and galaxies in the high-resolution simulations of the formation of galactic dark matter haloes of the Aquarius Project. The first star in a galaxy like the Milky Way formed around redshift z= 35; by z= 10, the young galaxy contained up to ∼3 × 104 dark matter haloes capable of forming stars by molecular hydrogen cooling. These minihaloes were strongly clustered, and feedback may have severely limited the actual number of Population III stars that formed. By the present day, the remnants of the first stars would be strongly concentrated to the centre of the main halo. If a second generation of long-lived stars formed near the first (the first star relics), we would expect to find half of them within 30 h−1 kpc of the Galactic Centre and a significant fraction in satellites where they may be singled out by their anomalous metallicity patterns. The first halo in which gas could cool by atomic hydrogen line radiation formed at z= 25; by z= 10, the number of such ‘first galaxies’ had increased to ∼300. Feedback might have decreased the number of first galaxies at the time when they undergo significant star formation, but not the number that survive to the present because near neighbours merge. Half of all the ‘first galaxies’ that formed before z= 10 merge with the main halo before z∼ 3 and most lose a significant fraction of their mass. However, today there should still be more than 20 remnants orbiting within the central ∼30 h−1 kpc of the Milky Way. These satellites have circular velocities of a few kilometres per second or more, comparable to those of known Milky Way dwarfs. They are a promising hunting ground for the remnants of the earliest epoch of star formation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".