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This study measured dust content in 25 star-forming galaxies at cosmic noon (z≈2.3) with subsolar metallicities using ALMA observations. The galaxies contain 4-9 times more dust than local galaxies with similar properties but significantly less than infrared-selected galaxies at the same epoch. The findings reveal that dust buildup becomes more efficient at higher metallicities, likely due to grain growth in the interstellar medium, and that high molecular gas fractions may explain the elevated dust-to-stellar mass ratios and star formation rates compared to local galaxies.
Why it matters
Understanding dust evolution in lower-mass, metal-poor galaxies during the universe's peak star formation era helps constrain models of galaxy evolution and chemical enrichment. These measurements provide crucial insights into how dust forms and accumulates in conditions different from the well-studied massive, metal-rich systems, filling an important observational gap.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: Dust plays a key role in galaxy evolution by influencing star formation and shaping the observed spectrum of galaxies. However, at $zsim2$ (cosmic noon) our knowledge of the dust mass budget is limited to the most massive, metal-rich systems. Here, we probe the lower mass, subsolar metallicity regime by measuring the dust mass of 25 galaxies at $zapprox2.3$ from the ALMA Chemical Evolution (ACE) survey. The sample contains star-forming galaxies in the COSMOS field with robust strong-line metallicities down to $sim 0.3Z_odot$. Using the dust continuum detected at 873$mu$m or 1.3mm we constrain the dust mass by assuming an optically thin single-temperature modified blackbody (MBB). The resulting masses of the detected galaxies have a median of $M_mathrm{dust}=6.4times10^{7},mathrm{M}_odot$, which is 4-9x larger than those of $z=0$ galaxies at matched metallicity and stellar mass, but more than 10x lower than IR-selected galaxies at $zapprox 2$. We 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 $10^{-2}$ but has no clear with metallicity unless we adopt a metallicity-dependent prescription for dust temperature. We also find a positive correlation between $M_mathrm{dust}/mathrm{SFR}$ and metallicity that suggests that dust buildup becomes more efficient at higher metallicities, likely due to the role of ISM grain growth or enhanced dust survival. We also recover the relation between DtS ratio and specific SFR (sSFR), without evidence of a turnover at high sSFR that would signal inefficient dust buildup. Finally, we measure a large molecular gas fraction among ACE CO(3-2)-detected galaxies ($M_mathrm{mol}/M_mathrm{stars}gtrsim$1) that potentially explains both the sSFR and DtS excess over $zapprox0$ galaxies.