Dust Grain Growth and Dusty Supernovae in Low-metallicity Molecular Clouds

We present 3D hydrodynamical models of the evolution of superbubbles powered by stellar winds and supernovae from young coeval massive star clusters within low-metallicity (Z = 0.02 Z(circle dot)), clumpy molecular clouds. We explore the initial stages of the superbubble evolution, including the occurrence of pair-instability and core-collapse supernovae. Our aim is to study the occurrence of dust grain growth within orbiting dusty clumps, and in the superbubble's swept-up supershell. We also aim to address the survival of dust grains produced by sequential supernovae. The model accounts for the star cluster gravitational potential and self-gravity of the parent cloud. It also considers radiative cooling (including that induced by dust) and a state-of-the-art population synthesis model for the coeval cluster. As shown before, a superbubble embedded into a clumpy medium becomes highly distorted, expanding mostly due to the hot gas streaming through low-density channels Our results indicate that in the case of massive (similar to 10 M-circle dot) molecular clouds, hosting a super star cluster (similar to 5.6 x 10(5) M-circle dot), grain growth increments the dust mass at a rate similar to 4.8 x 10(-5) M-circle dot yr(-1) during the first 2.5 Myr of the superbubble's evolution, while the net contribution of pair-instability and core-collapse supernovae to the superbubble's dust budget is similar to 1200 M circle dot (M-SC/5.6 x 10(5) M-circle dot), where M-SC is the stellar mass of the starburst. Therefore, dust grain growth and dust injection by supernovae lead to the creation of, without invoking a top-heavy initial mass function, massive amounts of dust within low-metallicity star-forming molecular clouds, in accordance with the large dust mass present in galaxies soon after the onset of cosmic reionization.