L. Arriscado | Searcharxiv

arXiv2026

ALMA Chemical Evolution (ACE) survey: The gas fundamental metallicity relation at cosmic noon

Chemical enrichment shapes how galaxies form and evolve. The gas-phase metallicity is directly linked to the stellar mass, star formation rate, and cold gas of the interstellar medium. Thus, the cold gas fundamental metallicity relation (GFMR) is a powerful tool for probing galaxy evolution, bridging large-scale gas flows modulating the cold gas reservoir and small-scale metal enrichment tracing the cumulative impact of star formation. Constraining all these properties for the same representative sample of galaxies remains challenging yet essential. Using CO(3--2) band 3 observations from the Atacama Large Millimeter/submillimeter Array Chemical Evolution (ACE) survey, we investigated the GFMR in a sample of 26 main-sequence (log(M_*, med)=9.96), subsolar-metallicity (12+log(O/H)_med=8.44) star-forming galaxies (SFGs) at z~2. With 17/26 CO detections, including some of the lowest-metallicity CO detections at cosmic noon, we find that the stellar mass remains the primary driver of the chemical evolution in our sample (sigmaMZR~0.10). Whereas the molecular gas likely plays a secondary role (sigmaGFMR~0.11) similar to that of the star formation rate (sigmaFMR~0.13). This likely reflects our sensitivity to only the CO-bright component of the molecular reservoir. Our results remain consistent with gas-regulator models and suggest the existence of efficient molecular outflows, with an average mass loading factor of eta~4, regulating star formation and chemical enrichment.

astro-ph.GA↗

arXiv2026

ALMA Chemical Evolution (ACE) survey: the dust content of subsolar metallicity galaxies at cosmic noon

Dust plays a key role in galaxy evolution by influencing star formation and shaping the observed spectrum of galaxies. However, at z~2 (cosmic noon) our knowledge of the dust mass budget is currently limited to the most massive, metal-rich systems, which are not representative of the bulk galaxy population. Here, we probe the lower mass, subsolar metallicity regime by measuring the dust mass of 25 galaxies at z~2.3 from the ALMA Chemical Evolution (ACE) Large Program. The sample contains star-forming galaxies in the COSMOS field with robust strong-line metallicities down to ~0.3 $Z_\odot$. Using the dust continuum emission detected at 873micron or 1.3mm we constrain the dust mass by assuming an optically thin single-temperature modified blackbody. The resulting dust masses average $10^{8}\,\mathrm{M}_\odot$, and they are three to nine times larger than those of z=0 galaxies at a matched metallicity and stellar mass. We also find positive correlations between dust mass and stellar mass, metallicity, and star formation rate (SFR). In contrast, we find that the $M_\mathrm{dust}/M_\mathrm{stars}$ (DtS) ratio scatters around $10^{-2.2}$ but shows no evidence of correlation with metallicity. This result is consistent with dust evolution models that predict a constant DtS once the ISM reaches the critical metallicity, at which metal accretion onto grains becomes the main mode of dust buildup. The correlation between $M_\mathrm{dust}/\mathrm{SFR}$ and metallicity also suggest that ACE galaxies have already surpassed the critical metallicity. Finally, we find that the DtS ratio is correlated to the specific SFR (sSFR). Since the sSFR are high ($> 10^{-8}\,\mathrm{yr}^{-1}$) this explains the DtS excess over z~0 galaxies. In turn, both sSFR and DtS are likely driven by the molecular gas fraction, as supported by CO(3-2) measurements taken as part of ACE.

astro-ph.GA↗