Molecular loops in the Galactic centre; evidence for magnetic floatation accelerating molecular gas

Extract

The new molecular image obtained by NANTEN telescope in the galactic center has revealed the existence of the two loop like structures, loop 1 and loop 2, which have never been seen before toward l = 355° to 358°. The velocities of loop 1 and loop 2 are −180 to −90 km s⁻¹ and −90 and −40 km s⁻¹, respectively, and these two loops have strong velocity gradients. The foot points of the loops show a very broad linewidth of ~40 to 80 km s⁻¹ whose large velocity spans are characteristic of the molecular gas near the galactic center. Therefore, we classified the loops as being located in the galactic center and adopt a distance of 8.5 kpc. Then, the projected lengths of loop 1 and loop 2 were estimated as ~500 and ~300 pc, respectively and velocity gradients corresponds to ~80 km s⁻¹ per 250 pc along loop 1 and ~60 km s⁻¹ per 150 pc along loop 2. The heights of these loops are also estimated as ~220 to ~300 pc from the galactic plane, significantly higher than the typical scale height in the nuclear disk.