Diverse Molecular Structures Across The Nearby Barred Spiral Galaxy M83 Revealed in CO(1-0) by ALMA

We present imaging of molecular gas across the full disk of the barred spiral galaxy M83 in CO(J=1-0). The data are taken with ALMA 12m, 7m, and Total Power arrays and imaged with the MIRIAD package. The molecular gas distribution shows coherent large-scale structures in the inner part (e.g., bar offset ridges, prominent molecular spiral arms). In the outer disk, however, while the molecular spiral arms are still present, they appear less coherent, even flocculent. Massive filamentary structures and giant molecular clouds (GMCs) are also present even in the interarm regions. Given that their formation timescales are expected to be very long in the interarm regions, the interarm molecular structures must have formed in stellar spiral arms and have been released into the interarm regions. Therefore, these molecular structures and embedded GMCs must have survived through the dynamical processes, suggesting their long lifetimes (~100Myr).