Spatially-resolved relation between [CI] ${}^3{P}_1$-${}^3{P}_0$ and ${}^{12}$CO (1-0) in Arp 220

Abstract

We present $\sim$0."3 (114 pc) resolution maps of [CI] ${}^3{P}_1$-${}^3{P}_0$ (hereafter [CI] (1-0)) and ${}^{12}$CO (1-0) obtained toward Arp 220 with the Atacama Large Millimeter/submillimeter Array. The overall distribution of the [CI] (1-0) emission is consistent with the CO (1-0). While the [CI] (1-0) and CO (1-0) luminosities of the system follow the empirical linear relation for the unresolved ULIRG sample, we find a sublinear relation between [CI] (1-0) and CO (1-0) using the spatially-resolved data. We measure the [CI] (1-0)/CO (1-0) luminosity ratio per pixel in star-forming environments of Arp 220 and investigate its dependence on the CO (3-2)/CO (1-0) ratio ($R_{\mathrm{CO}}$). On average, the [CI] (1-0)/CO (1-0) luminosity ratio is almost constant up to $R_{\mathrm{CO}}\simeq 1$ and then increases with $R_{\mathrm{CO}}$. According to the radiative transfer analysis, a high CI/CO abundance ratio is required in regions with high [CI] (1-0)/CO (1-0) luminosity ratios and $R_{\mathrm{CO}}>1$, suggesting that the CI/CO abundance ratio varies at $\sim$100 pc scale in Arp 220. The [CI] (1-0)/CO (1-0) luminosity ratio depends on multiple factors and may not be straightforward to interpret. We also find the high-velocity components traced by [CI] (1-0) in the western nucleus, likely associated with the molecular outflow. The [CI] (1-0)/CO (1-0) luminosity ratio in the putative outflow is 0.87 $\pm$ 0.28, which is four times higher than the average ratio of Arp 220. While there is a possibility that the [CI] (1-0) and CO (1-0) emission traces different components, we suggest that the high line ratios are likely because of elevated CI/CO abundance ratios based on our radiative transfer analysis. A CI-rich and CO-poor gas phase in outflows could be caused by the irradiation of the cosmic rays, the shock heating, and the intense radiation field.

arXiv comment16 pages, 10 Figures, 2 tables, accepted for publication in PASJ

References in corpus (42)

• The Global Schmidt Law in Star Forming Galaxies
• The CO-to-H2 Conversion Factor
• A computer program for fast non-LTE analysis of interstellar line spectra
• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• What Powers Ultra-luminous IRAS Galaxies?
• Molecular Gas at High Redshift
• Re-examining Larson's Scaling Relationships in Galactic Molecular Clouds
• xCOLD GASS: the complete IRAM-30m legacy survey of molecular gas for galaxy evolution studies
• Observations of Ultraluminous Infrared Galaxies with the Infrared Spectrograph on the Spitzer Space Telescope II: The IRAS Bright Galaxy Sample
• GOALS: The Great Observatories All-Sky LIRG Survey
• Diagnostics of irradiated dense gas in galaxy nuclei. II. A grid of XDR and PDR models
• Observations of Arp 220 using Herschel-SPIRE: An Unprecedented View of the Molecular Gas in an Extreme Star Formation Environment
• The CI lines as tracers of molecular gas, and their prospects at high redshifts
• Counterrotating Nuclear Disks in Arp 220
• Molecular gas in extreme star-forming environments: the starbursts Arp220 and NGC6240 as case studies
• A Survey of Atomic Carbon at High Redshift
• Star Formation in Extreme Environments: The Effects of Cosmic Rays and Mechanical Heating
• Effective destruction of CO by cosmic rays: implications for tracing H${}_2$ gas in the Universe
• L'CO/LFIR Relations with CO Rotational Ladders of Galaxies Across the Herschel SPIRE Archive
• SMA Imaging of CO(3-2) Line and 860 micron Continuum of Arp 220 : Tracing the Spatial Distribution of Luminosity
• ALMA observations of atomic carbon in z~4 dusty star-forming galaxies
• A Survey of Atomic Carbon [C I] in High-redshift Main-Sequence Galaxies
• The ALMA Spectroscopic Survey in the HUDF: CO Excitation and Atomic Carbon in Star-Forming Galaxies at $z=1-3$
• High-J CO Versus Far-Infrared Relations in Normal and Starburst Galaxies
• ALMA Resolves the Nuclear Disks of Arp 220
• CI emission in Ultra Luminous Infrared Galaxies as a molecular gas mass tracer
• CO/H2, C/CO, OH/CO, and OH/O2 in Dense Interstellar Gas: From High Ionization to Low Metallicity
• Fast, Collimated Outflow in the Western Nucleus of Arp 220
• Giant galaxy growing from recycled gas: ALMA maps the circumgalactic molecular medium of the Spiderweb in [CI]
• Neutral carbon and CO in 76 (U)LIRGs and starburst galaxy centers A method to determine molecular gas properties in luminous galaxies
• Neutral Carbon Emission in luminous infrared galaxies The \CI\ Lines as Total Molecular Gas Tracers
• Subarcsecond international LOFAR radio images of Arp 220 at 150 MHz: A kpc-scale star forming disk surrounding nuclei with shocked outflows
• New places and phases of CO-poor/CI-rich molecular gas in the Universe
• Resolved neutral carbon emission in nearby galaxies: [CI] Lines as Total Molecular Gas Tracers
• Gamma-Ray Emission from Arp 220: Indications of an Active Galactic Nucleus
• The subthermal excitation of the C{\sc i} lines in the molecular gas reservoirs of galaxies: its significance and potential utility
• High Atomic Carbon Abundance in Molecular Clouds in the Galactic Center Region
• ALMA Observations of Atomic Carbon [C I] (${{}^3\mathrm{P}}_1\to {{}^3\mathrm{P}}_0$) and Low-$J$ CO Lines in the Starburst Galaxy NGC 1808
• PdBI U/LIRG Survey (PULS): Dense Molecular Gas in Arp 220 and NGC 6240
• An ACA Survey of [CI] ${}^3{P}_1{-}^3{P}_0$, CO $J=4-3$, and Dust Continuum in Nearby U/LIRG
• Arp 220: New Observational Insights into the Structure and Kinematics of the Nuclear Molecular Disks and Surrounding Gas
• Atomic Carbon [CI]${(}^3{P}_1{-}^3{P}_0)$ Mapping of the Nearby Galaxy M83

Cited by in corpus (4)

• A sensitive APEX and ALMA CO(1-0), CO(2-1), CO(3-2), and [CI](1-0) spectral survey of 40 local (U)LIRGs
• No evidence of AGN features in the nuclei of Arp 220 from JWST/NIRSpec IFS
• JWST/NIRSpec insights into the circumnuclear region of Arp 220: A detailed kinematic study
• CI and CO in Nearby Spiral Galaxies -- I. Line Ratio and Abundance Variations at ~ 200 pc Scales