Discovery of Molecular and Atomic Clouds Associated with the Magellanic Superbubble 30 Doradus C

Abstract

We analyzed the 2.6-mm CO and 21-cm HI lines toward the Magellanic superbubble 30 Doradus C, in order to reveal the associated molecular and atomic gas. We uncovered five molecular clouds in a velocity range from 251 to 276 km s${}^{-1}$ toward the western shell. The non-thermal X-rays are clearly enhanced around the molecular clouds on a pc scale, suggesting possible evidence for magnetic field amplification via shock-cloud interaction. The thermal X-rays are brighter in the eastern shell, where there are no dense molecular or atomic clouds, opposite to the western shell. The TeV ${\hat{I}}^3$-ray distribution may spatially match the total interstellar proton column density as well as the non-thermal X-rays. If the hadronic ${\hat{I}}^3$-ray is dominant, the total energy of the cosmic-ray protons is at least $\sim 1.2\times 10^{50}$ erg with the estimated mean interstellar proton density $\sim 60$ cm${}^{-3}$. In addition the ${\hat{I}}^3$-ray flux associated with the molecular cloud (e.g., MC3) could be detected and resolved by the Cherenkov Telescope Array (CTA). This should permit CTA to probe the diffusion of cosmic-rays into the associated dense ISM.

9 pages, 5 figures, 1 table, accepted for publication in The Astrophysical Journal (ApJ)