Kiloparsec-scale Variations in the Star Formation Efficiency of Dense Gas: the Antennae Galaxies (NGC 4038/39)

Abstract

We study the relationship between dense gas and star formation in the Antennae galaxies by comparing ALMA observations of dense gas tracers (HCN, HCO${}^{+}$, and HNC $\mathrm{J}=1-0$) to the total infrared luminosity (${\mathrm{L}}_{\mathrm{TIR}}$) calculated using data from the \textit{Herschel} Space Observatory and the \textit{Spitzer} Space Telescope. We compare the luminosities of our SFR and gas tracers using aperture photometry and employing two methods for defining apertures. We taper the ALMA dataset to match the resolution of our ${\mathrm{L}}_{\mathrm{TIR}}$ maps and present new detections of dense gas emission from complexes in the overlap and western arm regions. Using OVRO CO $\mathrm{J}=1-0$ data, we compare with the total molecular gas content, $\mathrm{M}({\mathrm{H}}_2{)}_{\mathrm{tot}}$, and calculate star formation efficiencies and dense gas mass fractions for these different regions. We derive HCN, HCO${}^{+}$ and HNC upper limits for apertures where emission was not significantly detected, as we expect emission from dense gas should be present in most star-forming regions. The Antennae extends the linear ${\mathrm{L}}_{\mathrm{TIR}}-{\mathrm{L}}_{\mathrm{HCN}}$ relationship found in previous studies. The ${\mathrm{L}}_{\mathrm{TIR}}-{\mathrm{L}}_{\mathrm{HCN}}$ ratio varies by up to a factor of $\sim$10 across different regions of the Antennae implying variations in the star formation efficiency of dense gas, with the nuclei, NGC 4038 and NGC 4039, showing the lowest SFE${}_{\mathrm{dense}}$ (0.44 and 0.70 $\times 10^{-8}$ yr${}^{-1}$). The nuclei also exhibit the highest dense gas fractions ($\sim 9.1\%$ and $\sim 7.9\%$).

References in corpus (23)

• The NumPy array: a structure for efficient numerical computation
• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• The Critical Density and the Effective Excitation Density of Commonly Observed Molecular Dense Gas Tracers
• Diagnostics of irradiated dense gas in galaxy nuclei. II. A grid of XDR and PDR models
• Bias-free Measurement of Giant Molecular Cloud Properties
• A Parallax Distance to the Microquasar GRS 1915+105 and a Revised Estimate of its Black Hole Mass
• Modelling the Pan-Spectral Energy Distribution of Starburst Galaxies: IV The Controlling Parameters of the Starburst SED
• Luminous Infrared Galaxies with the Submillimeter Array: I. Survey Overview and the Central Gas to Dust Ratio
• Evidence of enhanced star formation efficiency in luminous and ultraluminous infrared galaxies
• A parsec-resolution simulation of the Antennae galaxies: Formation of star clusters during the merger
• Molecular Line Emission as a Tool for Galaxy Observations (LEGO). I. HCN as a tracer of moderate gas densities in molecular clouds and galaxies
• Turbulence sets the initial conditions for star formation in high-pressure environments
• A Portrait of Cold Gas in Galaxies at 60pc Resolution and a Simple Method to Test Hypotheses That Link Small-Scale ISM Structure to Galaxy-Scale Processes
• ALMA Observations of the Antennae Galaxies: I. A New Window on a Prototypical Merger
• HCN versus HCO+ as dense molecular gas mass tracer in Luminous Infrared Galaxies
• Mechanical feedback in the molecular ISM of luminous IR galaxies
• Millimeter-Wave Line Ratios and Sub-beam Volume Density Distributions
• Molecular gas heating mechanisms, and star formation feedback in merger/s tarbursts: NGC 6240 and Arp 193 as case studies
• The Physical Conditions in a Pre Super Star Cluster Molecular Cloud in the Antennae Galaxies
• The Global Star Formation Laws of Galaxies from a Radio Continuum Perspective
• Feedback in the Antennae Galaxies (NGC 4038/9): I. High-Resolution Infrared Spectroscopy of Winds from Super Star Clusters
• Optical Depth Estimates and Effective Critical Densities of Dense Gas Tracers in the Inner Parts of Nearby Galaxy Discs
• Mid-infrared diagnostics of starburst galaxies: clumpy, dense structures in star-forming regions in the Antennae (NGC 4038/4039)

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• Low-J CO Line Ratios From Single Dish CO Mapping Surveys and PHANGS-ALMA
• HCN/HNC intensity ratio: a new chemical thermometer for the molecular ISM
• Spatially resolved star formation and fuelling in galaxy interactions
• The ALMaQUEST Survey: II. What drives central starbursts at z~0?
• A diversity of starburst-triggering mechanisms in interacting galaxies and their signatures in CO emission
• The headlight cloud in NGC 628: An extreme giant molecular cloud in a typical galaxy disk
• The ALMaQUEST Survey X: What powers merger induced star formation?
• The ALMOND Survey: Molecular cloud properties and gas density tracers across 25 nearby spiral galaxies with ALMA
• LoTSS Jellyfish Galaxies IV: Enhanced Star Formation on the Leading Half of Cluster Galaxies and Gas Compression in IC3949
• A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946
• Highly turbulent gas on GMC-scales in NGC 3256, the nearest luminous infrared galaxy
• Planck's Dusty GEMS. VIII. Dense-gas reservoirs in the most active dusty starbursts at z~3
• Extreme Variation in Star Formation Efficiency Across a Compact, Starbursting Disk Galaxy
• Spatially Resolved Gas-phase Metallicity in FIRE-2 Dwarfs: Late-Time Evolution of Metallicity Relations in Simulations with Feedback and Mergers
• Fiery Cores: Bursty and Smooth Star Formation Distributions across Galaxy Centers in Cosmological Zoom-in Simulations
• A nearly constant CN/HCN line ratio in nearby galaxies: CN as a new tracer of dense gas
• Is this an Early Stage Merger? A Case Study on Molecular Gas and Star Formation Properties of Arp 240
• Gravitationally Bound Gas Determines Star Formation in the Galaxy
• Cold Molecular Gas in Merger Remnants. II. The properties of dense molecular gas
• Does the HCN/CO ratio trace the star-forming fraction of gas? I. A comparison with analytical models of star formation
• A 260 pc resolution ALMA map of HCN(1-0) in the galaxy NGC 4321
• Does the HCN/CO ratio trace the star-forming fraction of gas? II. Variations in CO and HCN Emissivity
• CN 2-1 and CS 5-4 observations toward Arp 299 with the SMA
• RIGEL: Feedback-regulated cloud-scale star formation efficiency in a simulated dwarf galaxy merger