Filamentary Fragmentation and Accretion in High-mass Star-forming Molecular Clouds

Filamentary structures are ubiquitous in high-mass star-forming molecular clouds. Their relation with high-mass star formation is still to be understood. Here we report interferometric observations toward eight filamentary high mass star-forming clouds. A total of 50 dense cores are identified in these clouds, most of which present signatures of high-mass star formation. Five of them are not associated with any star formation indicators and hence are prestellar core candidates. Evolutionary phases of these cores and their line widths, temperatures, NH3 abundances, and virial parameters are found to be correlated. In a subsample of four morphologically well-defined filaments, we find that their fragmentation cannot be solely explained by thermal or turbulence pressure support. We also investigate distributions of gas temperatures and nonthermal motions along the filaments and find a spatial correlation between nonthermal line widths and star formation activities. We find evidence of gas flows along these filaments and derive an accretion rate along filaments of similar to 10(-4) M-circle dot yr(-1). These results suggest a strong relationship between massive filaments and high-mass star formation, through (i) filamentary fragmentation in very early evolutionary phases to form dense cores, (ii) accretion flows along filaments that are important for the growth of dense cores and protostars, and (iii) enhancement of nonthermal motion in the filaments by the feedback or accretion during star formation.