TRAO survey of the nearby filamentary molecular clouds, the universal nursery of stars (TRAO-FUNS). IV. filaments and dense cores in the W40 and serpens south regions of aquila

Abstract

We present the results of molecular line observations toward the W40 and Serpens South regions of the Aquila molecular cloud complex, conducted as part of the Taeduk Radio Astronomy Observatory survey of Filaments, the Universal Nursery of Stars project to investigate the role of filamentary structures in the formation of dense cores and stars in molecular clouds. We performed a Gaussian decomposition of the C18O spectra to disentangle multiple velocity components along the line of sight and a "Friends-of-Friends" algorithm on these decomposed components to identify 24 velocity-coherent filaments in the observed region. The "FellWalker" algorithm is applied on the N2H+ integrated intensity map to identify the dense cores embedded within the filaments. Many of the filaments previously identified from the Herschel survey are found to contain multiple velocity-coherent filaments. Virial analysis indicated that all of our identified filaments are thermally supercritical and gravitationally bound. Velocity gradients are observed along the filaments in the vicinity of embedded dense cores, indicating the presence of longitudinal flows that contribute to core formation. The median mass flow rate across the observed region is estimated to be ∼35 M⊙ Myr−1, with Serpens South showing a rate ∼40% higher than W40. The analysis of nonthermal motions revealed that the dense cores mainly show subsonic to transonic motions, while their host filaments are mostly supersonic, suggesting that the turbulent motions in filaments may dissipate on smaller scales, allowing core formation. These findings highlight the essential role of the filaments' criticality, mass flow, and turbulent dissipation in the formation of dense cores within the filaments.