THE ORIGIN OF METALS IN THE CIRCUMGALACTIC MEDIUM OF MASSIVE GALAXIES AT<i>z</i>= 3
Bibliographic record
Abstract
We present a detailed study of the metal-enriched circumgalactic medium (CGM) of a massive galaxy at z = 3 using results from "ErisMC," a new cosmological hydrodynamic "zoom-in" simulation of a disk galaxy with mass comparable to the Milky Way. The reference run adopts a blast wave scheme for supernova feedback that generates galactic outflows without explicit wind particles, a star formation recipe based on a high gas density threshold and high-temperature metal cooling. ErisMC's main progenitor at z = 3 resembles a "Lyman break" galaxy of total mass M vir = 2.4 × 10 11 M ☉ , virial radius R vir = 48 kpc, and star formation rate 18 M ☉ yr −1 , and its metal-enriched CGM extends as far as 200 (physical) kpc from its center. Approximately 41%, 9%, and 50% of all gas-phase metals at z = 3 are locked in a hot ( T > 3 × 10 5 K), warm (3 × 10 5 K > T > 3 × 10 4 K), and cold ( T < 3 × 10 4 K) medium, respectively. We identify three sources of heavy elements: (1) the main host, responsible for 60% of all the metals found within 3 R vir ; (2) its satellite progenitors, which shed their metals before and during infall, and are responsible for 28% of all the metals within 3 R vir , and for only 5% of those beyond 3 R vir ; and (3) nearby dwarfs, which give origin to 12% of all the metals within 3 R vir and 95% of those beyond 3 R vir . Late ( z < 5) galactic "superwinds"—the result of recent star formation in ErisMC—account for only 9% of all the metals observed beyond 2 R vir , the bulk having been released at redshifts 5 ≲ z ≲ 8 by early star formation and outflows. In the CGM, lower overdensities are typically enriched by "older," colder metals. Heavy elements are accreted onto ErisMC along filaments via low-metallicity cold inflows and are ejected hot via galactic outflows at a few hundred km s −1 . The outflow mass-loading factor is of order unity for the main halo, but can exceed a value of 10 for nearby dwarfs. We stress that our "zoom-in" simulation focuses on the CGM of a single massive system and cannot describe the enrichment history of the intergalactic medium as a whole by a population of galaxies with different masses and star formation histories.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".