Cloud-cloud collision in Sgr B2
This is a short summary of our recent paper: https://arxiv.org/abs/2010.02757
In this paper we describe observations of the Sgr B2 molecular cloud, which is a star-forming region that inhabits the centre of our Galaxy. We report observations of a shock-tracer molecule, SiO, which show that Sgr B2 is potentially a region where clouds collided ~0.5Myr ago. This collision produced strong high-velocity shocks that ignited star formation during the early stages of the evolution, and also injected turbulence, whose supersonic nature is traced by CO and SiO emission lines. In this paper we show that the density structure and shock distribution of this region can be adequately reproduced by numerical simulations of colliding clouds. The movies from these simulations can be found below:
FIGURE 8:
<| 3D view of the cloud-cloud collision.
v| Zoomed-in 2D projection along the line-of-sight of the cloud-cloud collision shown on the left side.
FIGURE 11:
2D projections of the average shock velocities along the line-of-sight (LOS) for different velocity channels.
Shocks with velocities 5-50km/s are efficiently produced during the collision.
[-5,10] km/s
[10,25] km/s
[25,40] km/s
[40,55] km/s
[55,70] km/s
[70,85] km/s
[85,100] km/s
[100,115] km/s
Shock histogram
FIGURE 12:
2D histograms of number density (left) and column number density (right) versus shock velocity and average shock velocity along the LOS, respectively. High-velocity shocks are produced early on in the simulation, while moderate- and low-velocity shocks are produced later and can sustain SiO emission for ~0.5Myr.
FIGURE 13:
Position-velocity diagram during the cloud-cloud collision. The signs of a cloud-cloud collisions, i.e. the bridges, V-shaped features, and zig-zag features are present only in the early stages of the collisions. They vanish after 0.7 Myr.
