Cool interstellar medium as an evolutionary tracer in ALMA-observed local dusty early-type galaxies

ABSTRACT The content and distribution of cool interstellar medium (<30 K) can indicate the evolutionary mechanisms that transform late-type to early-type galaxies (ETGs). To investigate this, ALMA observations 12CO[2-1] line emission were obtained for five dusty ETGs from a complete sample in low-density environments. Four have massive (∼109 M⊙), extended molecular gas reservoirs with effective radii ∼3–5 kpc. This work provides kinematic structural analysis these observations, explore possible mechanisms. Axisymmetric or bisymmetric models fitted discs, quantify dominant structures present highlight additional asymmetries. Integral field unit also examined where available. Two ETGs, GAMA64646 622305, appear undergone tidal disturbance leading discs and/or star-forming inner rings. GAMA272990 may merger, an elliptical galaxy embedded disc. GAMA622429 has probably minor indicated by asymmetry optical images. remaining ETG, GAMA177186, was affected source confusion offset which could be high-mass dust- gas-rich object at high redshift. Overall, it appears proportion environments massive, reservoirs, some kind interaction as part their recent evolution. Secular evolution then (re-)transform passive galaxies.