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Observations are revealing the ubiquity of filamentary structures inmolecular clouds. As cores are often embedded in filaments, it is important tounderstand how line profiles from such systems differ from those of isolatedcores. We perform radiative transfer calculations on a hydrodynamic simulationof a molecular cloud in order to model line emission from collapsing coresembedded in filaments. We model two optically thick lines, CS(2-1) andHCN(1-0), and one optically thin line, N2H+(1-0), from three embedded cores. Inthe hydrodynamic simulation, gas self-gravity, turbulence, and bulk flowscreate filamentary regions within which cores form. Though the filaments havelarge dispersions, the N2H+(1-0) lines indicate subsonic velocities within thecores. We find that the observed optically thick line profiles of CS(2-1) andHCN(1-0) vary drastically with viewing angle. In over 50% of viewing angles,there is no sign of a blue asymmetry, an idealised signature of infall motionsin an isolated spherical collapsing core. Profiles which primarily trace thecores, with little contribution from the surrounding filament, arecharacterised by a systematically higher HCN(1-0) peak intensity. The N2H+(1-0)lines do not follow this trend. We demonstrate that red asymmetric profiles arealso feasible in the optically thick lines, due to emission from the filamentor one-sided accretion flows onto the core. We conclude that embedded cores mayfrequently undergo collapse without showing a blue asymmetric profile, and thatobservational surveys including filamentary regions may underestimate thenumber of collapsing cores if based solely on profile shapes of optically thicklines.

Line Profiles of Cores within Clusters: I. The Anatomy of a Filament