Dense Molecular Gas in the Nearby Low Metallicity Dwarf Starburst Galaxy IC 10

Abstract

Dense molecular gas and star formation are correlated in galaxies. The effect of low metallicity on this relationship is crucial for interpreting observations of high redshift galaxies, which have lower metallicities than galaxies today. However, it remains relatively unexplored because dense molecular gas tracers like HCN and HCO+ are faint in low metallicity systems. We present Green Bank Telescope observations of HCN(1-0) and HCO+(1-0) on giant molecular cloud (34pc) scales in the nearby low metallicity ($12+\log (O/H)=8.2$) starburst IC 10 and compare them to those in other galaxies. We detect HCN and HCO+ in one and three of five pointings, respectively. The $I_{\mathrm{HCN}}/I_{\mathrm{HCO}+}$ values are within the range seen in other galaxies, but are most similar to those seen in other low metallicity sources and in starbursts. The detections follow the fiducial $L_{\mathrm{IR}}$-$L_{\mathrm{HCN}}$ and $L_{\mathrm{IR}}$-$L_{\mathrm{HCO}+}$ relationships. These trends suggest that HCN and HCO+ can be used to trace dense molecular gas at metallicities of 1/4 $Z_{\odot }$, to first order. The dense gas fraction is similar to that in spiral galaxies, but lower than that in U/LIRGs. The dense molecular gas star formation efficiency, however, is on the upper end of those in normal galaxies and consistent with those in U/LIRGs. These results suggest that the CO and HCN/HCO+ emission occupy the same relative volumes as at higher metallicity, but that the entire emitting structure is reduced in size. Dense gas mass estimates for high redshift galaxies may need to be corrected for this effect.

arXiv commentAccepted to ApJ

References in corpus (50)

• The Star Formation Rate and Dense Molecular Gas in Galaxies
• Estimating Star Formation Rates from Infrared and Radio Luminosities: The Origin of the Radio-Infrared Correlation
• The Dark Molecular Gas
• xCOLD GASS: the complete IRAM-30m legacy survey of molecular gas for galaxy evolution studies
• HCN Survey of Normal Spiral, IR-luminous and Ultraluminous Galaxies
• Common-Resolution Convolution Kernels for Space- and Ground-Based Telescopes
• Low CO Luminosities in Dwarf Galaxies
• The Properties of Massive, Dense, Clumps: Mapping Surveys of HCN and CS
• Abundances of metal-rich H II regions in M51
• The anatomy of the Orion B Giant Molecular Cloud: A local template for studies of nearby galaxies
• Star formation laws in Luminous Infrared Galaxies. New observational constraints on models
• What Phase of the Interstellar Medium Correlates with the Star Formation Rate?
• Variations in the Star Formation Efficiency of the Dense Molecular Gas across the Disks of Star-Forming Galaxies
• Evidence of enhanced star formation efficiency in luminous and ultraluminous infrared galaxies
• CO Emission in Low Luminosity, HI Rich Galaxies
• Calibration of the total infrared luminosity of nearby galaxies from Spitzer and Herschel bands
• Is HCN a True Tracer of Dense Molecular Gas in LIRGs and ULIRGs?
• The EMPIRE Survey: Systematic Variations in the Dense Gas Fraction and Star Formation Efficiency from Full-Disk Mapping of M51
• Molecular Line Emission as a Tool for Galaxy Observations (LEGO). I. HCN as a tracer of moderate gas densities in molecular clouds and galaxies
• Enhanced Dense Gas Fraction in Ultra-Luminous Infrared Galaxies
• Molecular Gas in the Low Metallicity, Star Forming Dwarf IC 10
• Uncovering Additional Clues to Galaxy Evolution. I. Dwarf Irregulars in the Field
• Dense Gas, Dynamical Equilibrium Pressure, and Star Formation in Nearby Star-Forming Galaxies
• Physical Properties of Molecular Clouds at 2 parsec Resolution in the Low-Metallicity Dwarf Galaxy NGC 6822 and the Milky Way
• Excitation Mechanisms for HCN (1-0) and HCO+ (1-0) in Galaxies from the Great Observatories All-sky LIRG Survey
• Millimeter-Wave Line Ratios and Sub-beam Volume Density Distributions
• Dense Gas in the Milky Way
• The Metallicity Evolution of Star-Forming Galaxies from Redshift 0 to 3: Combining Magnitude Limited Survey with Gravitational Lensing
• Nobeyama Millimeter Interferometric HCN(1-0) and HCO+(1-0) Observations of Further Luminous Infrared Galaxies
• The final data release of ALLSMOG: a survey of CO in typical local low-M* star-forming galaxies
• HCN and HCO+ emission in the disk of M31
• IC 10: More evidence that it is a blue compact dwarf
• The Life and Death of Dense Molecular Clumps in the Large Magellanic Cloud
• The Molecular Interstellar Medium of the Local Group Dwarf NGC6822
• Linking Dense Gas from the Milky Way to External Galaxies
• The MUSE view of He 2-10: no AGN ionization but a sparkling starburst
• On the distance and reddening of the starburst galaxy IC10
• Spectral Line Survey toward Molecular Clouds in the Large Magellanic Cloud
• Dense Gas Fraction and Star Formation Efficiency Variations in the Antennae Galaxies
• The Galactic Census of High- and Medium-mass Protostars. II. Luminosities and Evolutionary States of a Complete Sample of Dense Gas Clumps
• Dense Gas in M33 (HerM33es)
• The Green Bank Telescope Maps the Dense, Star-Forming Gas in the Nearby Starburst Galaxy M82
• Spectral Line Survey toward a Molecular Cloud in IC10
• Dense gas in low-metallicity galaxies
• Dust and molecules in the Local Group galaxy NGC 6822. III. The first-ranked HII region complex Hubble V
• High Resolution Radio and Optical Observations of the Central Starburst in the Low-Metallicity Dwarf Galaxy II Zw 40
• Dense Gas in the Outer Spiral Arm of M51
• Resolving the molecular environment of Super Star Clusters in Henize 2-10
• Minimal HCN emission from Molecular Clouds in M33
• The Association of Molecular Gas and Natal Super Star Clusters in Henize 2-10

Cited by in corpus (10)

• EMPIRE: The IRAM 30-m Dense Gas Survey of Nearby Galaxies
• Dense gas is not enough: environmental variations in the star formation efficiency of dense molecular gas at 100pc scales in M51
• The headlight cloud in NGC 628: An extreme giant molecular cloud in a typical galaxy disk
• Dense molecular gas properties on 100 pc scales across the disc of NGC 3627
• DeGaS-MC: Dense Gas Survey in the Magellanic Clouds I -- An APEX survey of HCO+ and HCN(2-1) toward the LMC and SMC
• The Evolution of NGC 7465 as Revealed by its Molecular Gas Properties
• Tracers of Dense Gas in the Outer Galaxy
• A 260 pc resolution ALMA map of HCN(1-0) in the galaxy NGC 4321
• Tracing circumnuclear dense gas in H2O maser galaxies
• Electron density distribution in HII regions in IC10