VALES VI: ISM enrichment in star-forming galaxies up to z ∼ 0.2 using 12CO(1–0), 13CO(1–0), and C18O(1–0) line luminosity ratios. Issue 3 (7th July 2020)

• Record Type: Journal Article
• Authors: Méndez-Hernández, H; Ibar, E; Knudsen, K K; Cassata, P; Aravena, M; Michałowski, M J; Zhang, Zhi-Yu; Lara-López, M A; Ivison, R J; van der Werf, P; Villanueva, V; Herrera-Camus, R; Hughes, T M
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 497:Issue 3(2020)
• Page Start: 2771
• Page End: 2785
• Publication Date: 2020-07-07
• Subjects: methods: statistical -- techniques: interferometric -- galaxies: star formation -- galaxies: ISM; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa1964
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present Atacama Large Millimeter/sub-millimeter Array (ALMA) observations towards 27 low-redshift (0.02 < z < 0.2) star-forming galaxies taken from the Valparaíso ALMA/APEX Line Emission Survey. We perform stacking analyses of the 12 CO(1–0), 13 CO(1–0), and C 18 O(1–0) emission lines to explore the L ′ [ 12 CO(1–0)]/ L ′ [ 13 CO(1–0)] [hereafter L ′ ( 12 CO)/ L ′ ( 13 CO)] and L ′ [ 13 CO(1–0)]/ L ′ [C 18 O(1–0)] [hereafter L ′ ( 13 CO)/ L ′ (C 18 O)] line luminosity ratio dependence as a function of different global galaxy parameters related to the star formation activity. The sample has far-IR luminosities of $10^{10.1\!-\!11.9}\, $ L⊙ and stellar masses of 10 9.8–10.9 M⊙ corresponding to typical star-forming and starburst galaxies at these redshifts. On average, we find an L ′ ( 12 CO)/ L ′ ( 13 CO) line luminosity ratio value of 16.1 ± 2.5. Galaxies with pieces of evidence of possible merging activity tend to show higher L ′ ( 12 CO)/ L ′ ( 13 CO) ratios by a factor of 2, while variations of this order are also found in galaxy samples with higher star formation rates (SFRs) or star formation efficiencies (SFEs). We also find an average L ′ ( 13 CO)/ L ′ (C 18 O) line luminosity ratio of 2.5 ± 0.6, which is in good agreement with those previously reported for starburst galaxies. We find that galaxy samples with high L IR, SFR, and SFE show low L ′ ( 13 CO)/ L ′ (C 18 O) line luminosity ratios with high L ′ ( 12 CO)/ L ′ ( 13 CO) line luminosity ratios, suggesting that these trends are produced by selective enrichment of massive stars in young starbursts.