Molecular gas and star formation in nearby starburst galaxy mergers

Abstract

We employ the Feedback In Realistic Environments (FIRE-2) physics model to study how the properties of giant molecular clouds (GMCs) evolve during galaxy mergers. We conduct a pixel-by-pixel analysis of molecular gas properties in both the simulated control galaxies and galaxy major mergers. The simulated GMC-pixels in the control galaxies follow a similar trend in a diagram of velocity dispersion (${\sigma }_v$) versus gas surface density (${\Sigma }_{\mathrm{mol}}$) to the one observed in local spiral galaxies in the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) survey. For GMC-pixels in simulated mergers, we see a significant increase of factor of 5 - 10 in both ${\Sigma }_{\mathrm{mol}}$ and ${\sigma }_v$, which puts these pixels above the trend of PHANGS galaxies in the ${\sigma }_v$ vs ${\Sigma }_{\mathrm{mol}}$ diagram. This deviation may indicate that GMCs in the simulated mergers are much less gravitationally bound compared with simulated control galaxies with virial parameter (${\alpha }_{\mathrm{vir}}$) reaching 10 - 100. Furthermore, we find that the increase in ${\alpha }_{\mathrm{vir}}$ happens at the same time as the increase in global star formation rate (SFR), which suggests stellar feedback is responsible for dispersing the gas. We also find that the gas depletion time is significantly lower for high ${\alpha }_{\mathrm{vir}}$ GMCs during a starburst event. This is in contrast to the simple physical picture that low ${\alpha }_{\mathrm{vir}}$ GMCs are easier to collapse and form stars on shorter depletion times. This might suggest that some other physical mechanisms besides self-gravity are helping the GMCs in starbursting mergers collapse and form stars.

22 pages, 11 figures. Accepted to ApJ. Link to animation updated

References in corpus (50)

• The Resolved Properties of Extragalactic Giant Molecular Clouds
• xCOLD GASS: the complete IRAM-30m legacy survey of molecular gas for galaxy evolution studies
• Physical properties of molecular clouds for the entire Milky Way disk
• The lifecycle of molecular clouds in nearby star-forming disc galaxies
• Before the first supernova: combined effects of HII regions and winds on molecular clouds
• Starbursts triggered by inter-galactic tides and interstellar compressive turbulence
• Superbubbles in the Multiphase ISM and the Loading of Galactic Winds
• Mapping galaxy encounters in numerical simulations: The spatial extent of induced star formation
• Giant Molecular Cloud Catalogues for PHANGS-ALMA: Methods and Initial Results
• Observational Evidence of Dynamic Star Formation Rate in Milky Way Giant Molecular Clouds
• Molecular Gas Properties on Cloud Scales Across the Local Star-forming Galaxy Population
• Interacting galaxies on FIRE-2: The connection between enhanced star formation and interstellar gas content
• High-resolution simulations of galaxy mergers: Resolving globular cluster formation
• High-redshift major mergers weakly enhance star formation
• Deep learning predictions of galaxy merger stage and the importance of observational realism
• Molecular Cloud Populations in the Context of Their Host Galaxy Environments: A Multiwavelength Perspective
• 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
• FIREbox: Simulating galaxies at high dynamic range in a cosmological volume
• Spatially resolved star formation and fuelling in galaxy interactions
• Turbulent Gas in Lensed Planck-selected Starbursts at redshifts 1-3.5
• Efficient early stellar feedback can suppress galactic outflows by reducing supernova clustering
• Numerical Simulations of Turbulent, Molecular Clouds Regulated by Radiation Feedback Forces I: Star Formation Rate and Efficiency
• Disruption of giant molecular clouds and formation of bound star clusters under the influence of momentum stellar feedback
• Millimeter-Wave Line Ratios and Sub-beam Volume Density Distributions
• A Luminous Infrared Merger with Two Bipolar Molecular Outflows: ALMA and SMA Observations of NGC 3256
• Dust, CO and [CI]: Cross-calibration of molecular gas mass tracers in metal-rich galaxies across cosmic time
• The integrated properties of the molecular clouds from the JCMT CO(3-2) High Resolution Survey
• Exploring the physical properties of lensed star-forming clumps at $2\lesssim z\lesssim 6$
• Formation and evolution of young massive clusters in galaxy mergers: the SMUGGLE view
• Galaxy Pairs in the Sloan Digital Sky Survey - X: Does gas content alter star formation rate enhancement in galaxy interactions?
• The Mass-Size Relation and the Constancy of GMC Surface Densities in the Milky Way
• A diversity of starburst-triggering mechanisms in interacting galaxies and their signatures in CO emission
• The limited role of galaxy mergers in driving stellar mass growth over cosmic time
• The ALMaQUEST Survey X: What powers merger induced star formation?
• The role of gas fraction and feedback in the stability and evolution of galactic discs: implications for cosmological galaxy formation models
• A statistical study of giant molecular clouds traced by ${}^{13}$CO, C${}^{18}$O, CS, and CH${}_3$OH in the disk of NGC 1068 based on ALMA observations
• The combined and respective roles of imaging and stellar kinematics in identifying galaxy merger remnants
• VINTERGATAN-GM: The cosmological imprints of early mergers on Milky-Way-mass galaxies
• The Stellar Mass of M31 as inferred by the Andromeda Optical & Infrared Disk Survey
• The observability of galaxy merger signatures in nearby gas-rich spirals
• Shaping the structure of a GMC with radiation and winds
• Highly turbulent gas on GMC-scales in NGC 3256, the nearest luminous infrared galaxy
• Compact molecular gas emission in local LIRGs among low- and high-z galaxies
• Duality in spatially resolved star-formation relations in local LIRGs
• Realistic synthetic integral field spectroscopy with RealSim-IFS
• The Catalogue for Astrophysical Turbulence Simulations (CATS)
• Fiery Cores: Bursty and Smooth Star Formation Distributions across Galaxy Centers in Cosmological Zoom-in Simulations
• Extreme giant molecular clouds in the luminous infrared galaxy NGC 3256
• Does the HCN/CO ratio trace the star-forming fraction of gas? I. A comparison with analytical models of star formation

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• IllustrisTNG in the HSC-SSP: image data release and the major role of mini mergers as drivers of asymmetry and star formation
• Galaxy Mergers in the Epoch of Reionization I: A JWST Study of Pair Fractions, Merger Rates, and Stellar Mass Accretion Rates at $z=4.5-11.5$
• Disk settling and dynamical heating: histories of Milky Way-mass stellar disks across cosmic time in the FIRE simulations
• Transferring Data from a Voronoi Mesh to an Adaptive Cartesian Grid in Pursuit of Self-consistent Top-down Star Formation
• EMBERS I: Low redshift post-starburst galaxies are frequently depleted in molecular gas relative to star forming progenitors
• Merger Driven or Internal Evolution? A New Morphological Study of Tidal Disruption Event Host Galaxies