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Resolved Molecular Gas Observations of MaNGA Post-starbursts Reveal a Tumultuous Past

Presentation #241.02 in the session Evolution of Galaxies — iPoster Session.

Published onJun 29, 2022
Resolved Molecular Gas Observations of MaNGA Post-starbursts Reveal a Tumultuous Past

Post-starburst galaxies (PSBs) have recently and rapidly quenched their star-formation, making them an important population for understanding the processes that cause galaxies to transition from star-forming late-type galaxies to quiescent early-type galaxies. However, the recent discovery of large cold gas reservoirs in PSBs calls into question the theory that galaxies must expel or exhaust their gas to become quiescent. To better understand the mechanisms that quench star formation, we analyze a sample of 14 nearby (z < 0.1) PSBs with spatially resolved optical IFU data from the MaNGA survey and with matched resolution ALMA observations of 12CO(1-0). This unique sample allows us to study the molecular gas and star-formation properties on kpc scales and increases the total number of PSBs with resolved gas measurements by a factor of 3. We find centrally concentrated molecular gas morphologies, with ~75% of the molecular gas contained within 3-σ of the beam size, on average. We also see a diversity in the alignments of the kinematic axes of the stellar, ionized and molecular gas components, which depend on whether the post-starburst spaxels are centrally concentrated. We compare the molecular gas and star-formation rate surface densities of the post-starburst regions of galaxies in our sample to other star-forming galaxies and PSBs and find that star-formation tends to be suppressed in our PSBs with central post-starburst regions in particular. While the post-starburst regions in some of our galaxies are gas-poor with typical star-formation efficiencies, others display typical star-forming gas fractions with greatly reduced star-formation efficiencies. Overall, our results point to a major event disrupting the gas in these post-starbursts, driving it inwards and resulting in centrally concentrated gas reservoirs with varied kinematics that form stars at a suppressed rate.

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