TY - JOUR
T1 - Self-gravitating filament formation from shocked flows
T2 - Velocity gradients across filaments
AU - Chen, Che Yu
AU - Mundy, Lee G.
AU - Ostriker, Eve C.
AU - Storm, Shaye
AU - Dhabal, Arnab
N1 - Publisher Copyright:
© 2020 The Author(s).
PY - 2020
Y1 - 2020
N2 - In typical environments of star-forming clouds, converging supersonic turbulence generates shock-compressed regions, and can create strongly magnetized sheet-like layers. Numerical magnetohydrodynamic simulations show that within these post-shock layers, dense filaments and embedded self-gravitating cores form via gatheringmaterial along themagnetic field lines. As a result of the preferred-direction mass collection, a velocity gradient perpendicular to the filament major axis is a common feature seen in simulations.We show that this prediction is in good agreement with recent observations from theCARMALarge Area Star Formation Survey (CLASSy), from which we identified several filaments with prominent velocity gradients perpendicular to their major axes. Highlighting a filament from the north-west part of Serpens South, we provide both qualitative and quantitative comparisons between simulation results and observational data. In particular, we show that the dimensionless ratio Cv = Δvh2/(GM/L), where Δvh is half of the observed perpendicular velocity difference across a filament, and M/L is the filament's mass per unit length, can distinguish between filaments formed purely due to turbulent compression and those formed due to gravity-induced accretion.We conclude that the perpendicular velocity gradient observed in the Serpens South north-west filament can be caused by gravity-induced anisotropic accretion of material from a flattened layer. Using synthetic observations of our simulated filaments, we also propose that a density-selection effect may explain observed subfilaments (one filament breaking into two components in velocity space) as reported in recent observations.
AB - In typical environments of star-forming clouds, converging supersonic turbulence generates shock-compressed regions, and can create strongly magnetized sheet-like layers. Numerical magnetohydrodynamic simulations show that within these post-shock layers, dense filaments and embedded self-gravitating cores form via gatheringmaterial along themagnetic field lines. As a result of the preferred-direction mass collection, a velocity gradient perpendicular to the filament major axis is a common feature seen in simulations.We show that this prediction is in good agreement with recent observations from theCARMALarge Area Star Formation Survey (CLASSy), from which we identified several filaments with prominent velocity gradients perpendicular to their major axes. Highlighting a filament from the north-west part of Serpens South, we provide both qualitative and quantitative comparisons between simulation results and observational data. In particular, we show that the dimensionless ratio Cv = Δvh2/(GM/L), where Δvh is half of the observed perpendicular velocity difference across a filament, and M/L is the filament's mass per unit length, can distinguish between filaments formed purely due to turbulent compression and those formed due to gravity-induced accretion.We conclude that the perpendicular velocity gradient observed in the Serpens South north-west filament can be caused by gravity-induced anisotropic accretion of material from a flattened layer. Using synthetic observations of our simulated filaments, we also propose that a density-selection effect may explain observed subfilaments (one filament breaking into two components in velocity space) as reported in recent observations.
KW - ISM: clouds
KW - ISM: magnetic fields
KW - MHD
KW - Stars: formation
KW - Turbulence
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U2 - 10.1093/MNRAS/STAA960
DO - 10.1093/MNRAS/STAA960
M3 - Article
AN - SCOPUS:85092755773
SN - 0035-8711
VL - 494
SP - 3675
EP - 3685
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -