2018ApJ...853..169D

We present H¹³CO⁺ (J = 1-0) and HNC (J = 1-0) maps of regions in Serpens South, Serpens Main, and NGC 1333 containing filaments. We also observe the Serpens regions using H¹³CN (J = 1-0). These dense gas tracer molecular line observations carried out with CARMA have an angular resolution of ∼7'', a spectral resolution of ∼0.16 km s^–1, and a sensitivity of 50-100 mJy beam^–1. Although the large-scale structure compares well with the Herschel dust continuum maps, we resolve finer structure within the filaments identified by Herschel. The H¹³CO⁺ emission distribution agrees with the existing CARMA N₂H⁺ (J = 1-0) maps, so they trace the same morphology and kinematics of the filaments. The H¹³CO⁺ maps additionally reveal that many regions have multiple structures partially overlapping in the line of sight. In two regions, the velocity differences are as high as 1.4 km s^–1. We identify eight filamentary structures having typical widths of 0.03-0.08 pc in these tracers. At least 50% of the filamentary structures have distinct velocity gradients perpendicular to their major axis, with average values in the range of 4-10 km s^–1 pc^–1. These findings are in support of the theoretical models of filament formation by 2D inflow in the shock layer created by colliding turbulent cells. We also find evidence of velocity gradients along the length of two filamentary structures; the gradients suggest that these filaments are inflowing toward the cloud core.