A cloud-cloud collision in Sgr B2? 3D simulations meet SiO observations

Abstract

AbstractWe compare the properties of shocked gas in Sgr B2 with maps obtained from 3D simulations of a collision between two fractal clouds. In agreement with 13CO(1-0) observations, our simulations show that a cloud-cloud collision produces a region with a highly turbulent density substructure with an average . Similarly, our numerical multi-channel shock study shows that colliding clouds are efficient at producing internal shocks with velocities of 5 − 50 km s−1 and Mach numbers of ∼ 4 − 40, which are needed to explain the ∼ 10−9 SiO abundances inferred from our SiO(2-1) IRAM observations of Sgr B2. Overall, we find that both the density structure and the shocked gas morphology in Sgr B2 are consistent with a Myr-old cloud-cloud collision. High-velocity shocks are produced during the early stages of the collision and can ignite star formation, while moderate- and low-velocity shocks are important over longer time-scales and can explain the extended SiO emission in Sgr B2.