Do post-starburst galaxies host compact molecular gas reservoirs?

Fengwu Sun, Eiichi Egami

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


We analysed the high-resolution (up to ∼0.2 arcsec) ALMA CO (2-1) and 1.3 mm dust continuum data of eight gas-rich post-starburst galaxies (PSBs) in the local Universe, six of which had been studied by a recent work. In contrast to this study reporting the detections of extraordinarily compact (i.e. unresolved) reservoirs of molecular gas in the six PSBs, our visibility-plane analysis resolves the CO (2-1) emission in all eight PSBs with effective radii (Re, CO) of 0.8-0.4+0.9 kpc, typically consisting of gaseous components at both circumnuclear and extended disc scales. With this new analysis, we find that the CO sizes of gas-rich PSBs are compact with respect to their stellar sizes (median ratio =0.43-0.21+0.27), but comparable to the sizes of the gas discs seen in local luminous infrared galaxies (LIRGs) and early-type galaxies. We also find that the CO-to-stellar size ratio of gas-rich PSBs is potentially correlated with the gas depletion time-scale, placing them as transitional objects between LIRGs and early-type galaxies from an evolutionary perspective. Finally, the star formation efficiency of the observed PSBs appear consistent with those of star-forming galaxies on the Kennicutt-Schmidt relation, showing no sign of suppressed star formation from turbulent heating.

Original languageEnglish (US)
Pages (from-to)L126-L131
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
StatePublished - Nov 1 2022


  • galaxies: ISM
  • galaxies: evolution
  • galaxies: star formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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