${}^{13}$CO/C${}^{18}$O Gradients Across the Disks of Nearby Spiral Galaxies

Abstract

We use the IRAM Large Program EMPIRE and new high-resolution ALMA data to measure 13CO(1-0)/C18O(1-0) intensity ratios across nine nearby spiral galaxies. These isotopologues of CO are typically optically thin across most of the area in galaxy disks, and this ratio allows us to gauge their relative abundance due to chemistry or stellar nucleosynthesis effects. Resolved 13CO/C18O gradients across normal galaxies have been rare due to the faintness of these lines. We find a mean 13CO/C18O ratio of 6.0$\pm$0.9 for the central regions of our galaxies. This agrees well with results in the Milky Way, but differs from results for starburst galaxies (3.4$\pm$0.9) and ultraluminous infrared galaxies (1.1$\pm$0.4). In our sample, the 13CO/C18O ratio consistently increases with increasing galactocentric radius and decreases with increasing star formation rate surface density. These trends qualitatively agree with expectations for carbon and oxygen isotopic abundance variations due to stellar nucleosynthesis, with a possible effect of fractionation.

References in corpus (25)

• Calibrating Extinction-Free Star Formation Rate Diagnostics with 33GHz Free-Free Emission in NGC6946
• Molecular Gas and Star Formation in Nearby Disk Galaxies
• Re-examining Larson's Scaling Relationships in Galactic Molecular Clouds
• HERACLES: The HERA CO-Line Extragalactic Survey
• A Molecular Star Formation Law in the Atomic Gas Dominated Regime in Nearby Galaxies
• The Spitzer Local Volume Legacy: Survey Description and Infrared Photometry
• Common-Resolution Convolution Kernels for Space- and Ground-Based Telescopes
• KINGFISH -- Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel: Survey Description and Image Atlas
• CO Isotopologues in the Perseus Molecular Cloud Complex: the X-Factor and Regional Variations
• Molecular gas in extreme star-forming environments: the starbursts Arp220 and NGC6240 as case studies
• Calibration of the total infrared luminosity of nearby galaxies from Spitzer and Herschel bands
• Molecules as tracers of galaxy evolution: an EMIR survey. I. Presentation of the data and first results
• The EMPIRE Survey: Systematic Variations in the Dense Gas Fraction and Star Formation Efficiency from Full-Disk Mapping of M51
• A high-dispersion molecular gas component in nearby galaxies
• On carbon and oxygen isotope ratios in starburst galaxies: New data from NGC253 and Mrk231 and their implications
• DESPOTIC -- A New Software Library to Derive the Energetics and SPectra of Optically Thick Interstellar Clouds
• Galactic interstellar 18O/17O ratios - a radial gradient?
• A lambda=3 mm molecular line survey of NGC1068. Chemical signatures of an AGN environment
• 13CO and C18O emission from a dense gas disk at z=2.3: abundance variations, cosmic rays and the initial conditions for star formation
• Optical Depth Estimates and Effective Critical Densities of Dense Gas Tracers in the Inner Parts of Nearby Galaxy Discs
• Dynamically Influenced Molecular Clouds in the Nucleus of NGC 6946: Variations in the CO Isotopic Line Ratios
• Chemistry and radiative shielding in star forming galactic disks
• Nuclear Bar Catalyzed Star Formation: 13^CO, C18^O and Molecular Gas Properties in the Nucleus of Maffei 2
• Systematic variation of the 12CO/13CO ratio as a function of star-formation rate surface density
• 12CO, 13CO and C18O observations along the major axes of nearby bright infrared galaxies

Cited by in corpus (39)

• Stellar populations dominated by massive stars in dusty starburst galaxies across cosmic time
• The evolution of CNO isotopes: a new window on cosmic star-formation history and the stellar IMF in the age of ALMA
• CHAOS IV: Gas-Phase Abundance Trends From The First Four CHAOS Galaxies
• EMPIRE: The IRAM 30-m Dense Gas Survey of Nearby Galaxies
• New Constraints on the ${}^{12}$CO(2-1)/(1-0) Line Ratio Across Nearby Disc Galaxies
• Dense Gas, Dynamical Equilibrium Pressure, and Star Formation in Nearby Star-Forming Galaxies
• Full-disc ${}^{13}$CO(1-0) mapping across nearby galaxies of the EMPIRE survey and the CO-to-H${}_2$ conversion factor
• Identification of Low Surface Brightness Tidal Features in Galaxies Using Convolutional Neural Networks
• Gas phase Elemental abundances in Molecular cloudS (GEMS). IV. Observational results and statistical trends
• Molecular Gas Properties and CO-to-H2 Conversion Factors in the Central Kiloparsec of NGC 3351
• Extreme CO Isotopic Abundances in the ULIRG IRAS 13120-5453: An Extremely Young Starburst or Top-Heavy Initial Mass Function
• Extreme CO Isotopologue Line Ratios in ULIRGS: Evidence for a top-heavy IMF
• The ALMA Detection of Extraplanar 13CO in a Ram-pressure-stripped Galaxy and Its Implication
• Spatially resolved carbon and oxygen isotopic ratios in NGC 253 using optically thin tracers
• Bright Extragalactic ALMA Redshift Survey (BEARS) III: Detailed study of emission lines from 71 Herschel targets
• A CO isotopologue Line Atlas within the Whirlpool galaxy Survey (CLAWS)
• CO Multi-line Imaging of Nearby Galaxies (COMING). III. Dynamical effect on molecular gas density and star formation in the barred spiral galaxy NGC 4303
• Luminous Infrared Galaxies with the Submillimeter Array V: Molecular Gas in Intermediate to Late-stage Mergers
• Unusual Isotopic Abundances in a Fully-Convective Stellar Binary
• An H-band Vector Vortex Coronagraph for the Subaru Coronagraphic Extreme-Adaptive Optics System
• PdBI U/LIRG Survey (PULS): Dense Molecular Gas in Arp 220 and NGC 6240
• Wide-field CO isotopologue emission and the CO-to-H${}_2$ factor across the nearby spiral galaxy M101
• The Evolution of NGC 7465 as Revealed by its Molecular Gas Properties
• A 3 mm Spectral Line Survey toward the Barred Spiral Galaxy NGC 3627
• TIMES I: a Systematic Observation in Multiple Molecular Lines Toward the Orion A and Ophiuchus Clouds
• SMA Observations of Extended $\mathrm{CO}(\mathrm{J}=2-1)$ Emission in Interacting Galaxy NGC 3627
• VALES VI: ISM enrichment in star-forming galaxies up to z$\sim$0.2 using ${}^{12}$CO(1-0), ${}^{13}$CO(1-0) and C${}^{18}$O(1-0) line luminosity ratios
• Simultaneous Deep Measurements of CO isotopologues and Dust Emission in Giant Molecular Clouds in the Andromeda Galaxy
• CO emission and CO hotspots in diffuse molecular gas
• Molecular Gas of the Most Massive Spiral Galaxies I: a Case Study of NGC 5908
• Planck Galactic Cold Clumps at High Galactic Latitude-A Study with CO Lines
• CO-CHANGES I: IRAM 30m CO Observations of Molecular Gas in the Sombrero Galaxy
• Down but not out: properties of the molecular gas in the stripped Virgo Cluster early-type galaxy NGC4526
• Opacities of dense gas tracers in galactic massive star-forming regions
• CO-CHANGES II: spatially resolved IRAM 30M CO line observations of 23 nearby edge-on spiral galaxies
• ${}^{14}$N${/}^{15}$N abundance ratio toward massive star-forming regions with different Galactic distances
• VERTICO IX: Signatures of environmental processing of the gas in Virgo cluster spiral galaxies through mapping of CO isotopologues
• Surveying the Whirlpool at Arcseconds with NOEMA (SWAN): III. ${}^{13}$CO/C${}^{18}$O ratio variations across the M51 galaxy
• The AGN fuelling/feedback cycle in nearby radio galaxies -- IV. Molecular gas conditions and jet-ISM interaction in NGC3100