Filament Formation via Collision-induced Magnetic Reconnection -- Kinematic Features

RESUMO

The Collision-induced Magnetic Reconnection (CMR) mechanism has recently been proposed as a filament formation model that emphasizes the active role of magnetic fields. To enable better observational tests with data from modern telescopes, we provide more specific observable predictions for filaments formed via CMR. Two types of CMR kinematics are revealed in position-velocity (PV) diagrams. First, due to the nature of CMR, the midplane contains a {\it converging motion} close to the filament and two {\it diverging motions} farther from the filament. They exhibit a blueshift, redshift, blueshift, redshift (BRBR) velocity pattern along the line-of-sight when the collision midplane is inclined, giving rise to a special pattern in the PV-diagram. Second, the longitudinal PV-diagram along the filament spine exhibits a velocity oscillating pattern, which is currently attributed to the magnetic transport of gas clumps in the {\it converging motion}. The first type of pattern involves emission primarily outside the filament, which can be confused with the environment. The second type, however, mainly emerges from gas inside the filament, thus more robust for observational tests. Both the integral-shaped filament and the Stick filament in the Orion A cloud show the velocity oscillation in PV-diagrams, although the spatial oscillation frequency and their velocity spread differ.