2024/10/07 by Hirota, Akihiko, Koda, Jin, Egusa, Fumi +17 · 2 citations
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2410.05424
We present a catalog of clouds identified from the 12CO (1--0) data of M83, which was observed using Atacama Large Millimeter/submillimeter Array (ALMA) with a spatial resolution of ∼46 pc and a mass sensitivity of ∼104 M\odot (3 σ). The almost full-disk coverage and high sensitivity of the data allowed us to sample 5724 molecular clouds with a median mass of ∼1.9 × 105 M\odot, which is comparable to the most frequently sampled mass of Giant Molecular Clouds by surveys in the Milky Way. About 60 percent of the total CO luminosity in M83's disk arises from clouds more massive than 106 M\odot. Such massive clouds comprise 16 percent of the total clouds in number and tend to concentrate toward the arm, bar, and center, while smaller clouds are more prevalent in inter-arm regions. Most >106 M\odot clouds have peak brightness temperatures Tpeak above 2 K with the current resolution. Comparing the observed cloud properties with the scaling relations determined by Solomon et al. 1987 (S87), Tpeakgt;2 K clouds follow the relations, but Tpeak<2 K clouds, which are dominant in number, deviate significantly. Without considering the effect of beam dilution, the deviations would suggest modestly high virial parameters and low surface mass densities for the entire cloud samples, which are similar to values found for the Milky Way clouds by Rice et al. (2016) and Miville-Deschênes et al. (2017). However, once beam dilution is taken into account, the observed αvir and Σ for a majority of the clouds (mostly Tpeak <2 K) can be potentially explained with intrinsic Σ of ∼100 M\odot pc-2 and αvir of ∼1, which are similar to the clouds of S87.