2023ApJ...955...52T

Recent millimeter/submillimeter facilities have revealed the physical properties of filamentary molecular clouds in relation to high-mass star formation. A uniform survey of the nearest, face-on star-forming galaxy, the Large Magellanic Cloud (LMC), complements the Galactic knowledge. We present ALMA survey data with a spatial resolution of ∼0.1 pc in the 0.87 mm continuum and HCO⁺ (4-3) emission toward 30 protostellar objects with luminosities of 10⁴-10^5.5L_⊙ in the LMC. The spatial distributions of the HCO⁺ (4-3) line and thermal dust emission are well correlated, indicating that the line effectively traces dense, filamentary gas with an H₂ volume density of ≳10⁵ cm^–3 and a line mass of ∼10³-10⁴M_⊙ pc^–1. Furthermore, we obtain an increase in the velocity line widths of filamentary clouds, which follows a power-law dependence on their H₂ column densities with an exponent of ∼0.5. This trend is consistent with observations toward filamentary clouds in nearby star-forming regions within ≲1 kpc from us and suggests enhanced internal turbulence within the filaments due to surrounding gas accretion. Among the 30 sources, we find that 14 are associated with hub-filamentary structures, and these complex structures predominantly appear in protostellar luminosities exceeding ∼5 × 10⁴L_⊙. The hub-filament systems tend to appear in the latest stages of their natal cloud evolution, often linked to prominent H II regions and numerous stellar clusters. Our preliminary statistics suggest that the massive filaments accompanied by hub-type complex features may be a necessary intermediate product in forming extremely luminous high-mass stellar systems capable of ultimately dispersing the parent cloud.