After The Fall: Resolving the Molecular Gas in Post-Starburst Galaxies

Abstract

Post-starburst (PSB), or 'E+A', galaxies represent a rapid transitional phase between major, gas-rich mergers and gas-poor, quiescent early-type galaxies. Surprisingly, many PSBs have been shown to host a significant interstellar medium (ISM), despite theoretical predictions that the majority of star-forming gas should be expelled in AGN- or starburst-driven outflows. To-date, the resolved properties of this surviving ISM have remained unknown. We present high resolution ALMA continuum and CO(2$-$1) observations in six gas- and dust-rich PSBs, revealing for the first time the spatial and kinematic structure of their ISM on sub-kpc scales. We find extremely compact molecular reservoirs, with dust and gas surface densities rivaling those found in (ultra-)luminous infrared galaxies. We observe spatial and kinematic disturbances in all sources, with some also displaying disk-like kinematics. Estimates of the internal turbulent pressure in the gas exceed those of normal star-forming disks by at least 2 orders of magnitude, and rival the turbulent gas found in local interacting galaxies, such as the Antennae. Though the source of this high turbulent pressure remains uncertain, we suggest that the high incidence of tidal disruption events (TDEs) in PSBs could play a role. The star formation in these PSBs' turbulent central molecular reservoirs is suppressed, forming stars only 10% as efficiently as starburst galaxies with similar gas surface densities. "The fall" of star formation in these galaxies was not precipitated by complete gas expulsion or redistribution. Rather, this high-resolution view of PSBs' ISM indicates that star formation in their remaining compact gas reservoirs is suppressed by significant turbulent heating.

19 pages, 9 figures, 3 tables; Accepted for publication in ApJ

References in corpus (25)

• Array Programming with NumPy
• The NumPy array: a structure for efficient numerical computation
• Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
• A parsec-resolution simulation of the Antennae galaxies: Formation of star clusters during the merger
• Revisiting the Integrated Star Formation Law. Paper I: Non-Starbursting Galaxies
• New Constraints on the ${}^{12}$CO(2-1)/(1-0) Line Ratio Across Nearby Disc Galaxies
• Discovery of Large Molecular Gas Reservoirs in Post-Starburst Galaxies
• Revisiting the Integrated Star Formation Law. II. Starbursts and the Combined Global Schmidt Law
• Suppression of Star Formation in NGC 1266
• Cold Molecular Gas in Merger Remnants: I. Formation of Molecular Gas Disks
• The evolution of the cold interstellar medium in galaxies following a starburst
• Millimeter-Wave Line Ratios and Sub-beam Volume Density Distributions
• Massive Compact Galaxies with High-Velocity Outflows: Morphological Analysis and Constraints on AGN Activity
• Powerful H2 Line Cooling in Stephan's Quintet II. Group-wide Gas and Shock Modeling of the Warm H2 and a Comparison with [CII]157.7um Emission and Kinematics
• ALMA 200 pc imaging of a z~7 quasar reveals a compact, disk-like host galaxy
• E+A Galaxies with Blue Cores: Active Galaxies in Transition
• First light from tidal disruption events
• Distinguishing Tidal Disruption Events from Impostors
• Dense molecular gas properties on 100 pc scales across the disc of NGC 3627
• Strong Far-IR Cooling Lines, Peculiar CO Kinematics and Possible Star Formation Suppression in Hickson Compact Group 57
• The Evolution of the Interstellar Medium in Post-Starburst Galaxies
• Highly turbulent gas on GMC-scales in NGC 3256, the nearest luminous infrared galaxy
• The Star Formation History of a Post-Starburst Galaxy Determined From Its Cluster Population
• On the quenching of star formation in observed and simulated central galaxies: Evidence for the role of integrated AGN feedback

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• Interacting galaxies in the IllustrisTNG simulations -- IV: Enhanced Supermassive Black Hole Accretion Rates in Post-Merger Galaxies
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• Molecular Gas Reservoirs in Massive Quiescent Galaxies at $\mathrm{z}\sim 0.7$ Linked to Late Time Star Formation
• The Compact Structures of Massive $z\sim 0.7$ Post-Starburst Galaxies in the SQuIGG$\vec{L}$E Sample
• Post-Starburst Properties of Post-Merger Galaxies
• The State of the Molecular Gas in Post-Starburst Galaxies
• A Multiwavelength view of IC 860: What Is in Action inside Quenching Galaxies
• Star formation and molecular gas properties of post-starburst galaxies
• Resolved Molecular Gas Observations of MaNGA Post-starbursts Reveal a Tumultuous Past
• The large molecular gas fraction of post-starburst galaxies at z > 1
• The molecular gas resolved by ALMA in the low-metallicity dwarf merging galaxy Haro 11
• No evidence for excess AGN activity in recently quenched massive galaxies at cosmic noon
• The fate of the interstellar medium in early-type galaxies. III. The mechanism of ISM removal and quenching of star formation
• Evolution of Gas Flows along the Starburst to Post-Starburst to Quiescent Galaxy Sequence
• Do Post-Starburst Galaxies Host Compact Molecular Gas Reservoirs?
• Central Concentration of Asymmetric Features in Post-starburst Galaxies at $z\sim 0.8$
• Shocked POststarburst Galaxy Survey. IV. Outflows in Shocked Post-Starburst Galaxies Are Not Responsible For Quenching
• An Imaging and Spectroscopic Exploration of the Dusty Compact Obscured Nucleus Galaxy Zw~049.057
• Radio Variability in Recently-Quenched Galaxies: The Impact of TDE or AGN Driven Outflows
• Clumpy Starburst in a Local Dwarf Galaxy, NGC 1522
• EMBERS I: Low redshift post-starburst galaxies are frequently depleted in molecular gas relative to star forming progenitors