The atomic-to-molecular gas conversion is a critical step in the baryon cycle of galaxies,which sets the initial conditions for subsequent star formation and influences the multi-phase interstellar medium.We compiled ...The atomic-to-molecular gas conversion is a critical step in the baryon cycle of galaxies,which sets the initial conditions for subsequent star formation and influences the multi-phase interstellar medium.We compiled a sample of 94 nearby galaxies with observations of multi-phase gas contents by utilizing public H_(Ⅰ),CO,and optical IFU data from the Ma NGA survey together with new FAST H_(Ⅰ)observations.In agreement with previous results,our sample shows that the global molecular-to-atomic gas ratio(R_(mol)≡log M_(H2)/M_(H_(Ⅰ)))is correlated with the global stellar mass surface densityμ_*with a Kendall'sτcoefficient of 0.25 and p<10^(-3),less tightly but still correlated with stellar mass and NUV-r color,and not related to the specific star formation rate(sSFR).The cold gas distribution and kinematics inferred from the H_(Ⅰ)and CO global profile asymmetry and shape do not significantly rely on R_(mol).Thanks to the availability of kpc-scale observations of MaNGA,we decompose galaxies into H_(Ⅱ),composite,and AGN-dominated regions by using the BPT diagrams.With increasing R_(mol),the fraction of H_(Ⅱ)regions within 1.5 effective radius decreases slightly;the density distribution in the spatially resolved BPT diagram also changes significantly,suggesting changes in metallicity and ionization states.Galaxies with high R_(mol)tend to have high oxygen abundance,both at one effective radius with a Kendall'sτcoefficient of 0.37(p<10^(-3))and their central regions.Among all parameters investigated here,the oxygen abundance at one effective radius has the strongest relation with global R_(mol).The dependence of gas conversion on gas distribution and galaxy ionization states is weak.In contrast,the observed positive relation between oxygen abundance(μ_(*))and R_(mol)indicates that the gas conversion is efficient in regions of high metallicity(density).展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11988101,11973051,12041302,12373012,11903003,and U1931110)the support by the National Natural Science Foundation of China(Grant No.11973030)+6 种基金the China Postdoctoral Science Foundation(Grant Nos.2022M723175,and GZB20230766)the International Partnership Program of Chinese Academy of Sciences(Grant No.114A11KYSB20210010)the National Key Research and Program of China(Grant Nos.2023YFE0110500,2023YFA1608004,and 2023YFC2206403)the Ministry of Science and Technology of China(Grant No.2022YFA1605300)supported by the Young Researcher Grant of Institutional Center for Shared Technologies and Facilities of National Astronomical Observatories,Chinese Academy of Sciencesthe fellowship of China National Postdoctoral Program for Innovation Talents(Grant No.BX20220301)supported by the project funded by China Postdoctoral Science Foundation(Grant No.2021M703236)。
文摘The atomic-to-molecular gas conversion is a critical step in the baryon cycle of galaxies,which sets the initial conditions for subsequent star formation and influences the multi-phase interstellar medium.We compiled a sample of 94 nearby galaxies with observations of multi-phase gas contents by utilizing public H_(Ⅰ),CO,and optical IFU data from the Ma NGA survey together with new FAST H_(Ⅰ)observations.In agreement with previous results,our sample shows that the global molecular-to-atomic gas ratio(R_(mol)≡log M_(H2)/M_(H_(Ⅰ)))is correlated with the global stellar mass surface densityμ_*with a Kendall'sτcoefficient of 0.25 and p<10^(-3),less tightly but still correlated with stellar mass and NUV-r color,and not related to the specific star formation rate(sSFR).The cold gas distribution and kinematics inferred from the H_(Ⅰ)and CO global profile asymmetry and shape do not significantly rely on R_(mol).Thanks to the availability of kpc-scale observations of MaNGA,we decompose galaxies into H_(Ⅱ),composite,and AGN-dominated regions by using the BPT diagrams.With increasing R_(mol),the fraction of H_(Ⅱ)regions within 1.5 effective radius decreases slightly;the density distribution in the spatially resolved BPT diagram also changes significantly,suggesting changes in metallicity and ionization states.Galaxies with high R_(mol)tend to have high oxygen abundance,both at one effective radius with a Kendall'sτcoefficient of 0.37(p<10^(-3))and their central regions.Among all parameters investigated here,the oxygen abundance at one effective radius has the strongest relation with global R_(mol).The dependence of gas conversion on gas distribution and galaxy ionization states is weak.In contrast,the observed positive relation between oxygen abundance(μ_(*))and R_(mol)indicates that the gas conversion is efficient in regions of high metallicity(density).
