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High-velocity atomic clouds in the Galactic centre have attracted significant attention due to their enigmatic formation process, which is potentially linked to the starburst or supermassive black hole activities in the region. Further, the discovery of high-velocity molecular clouds (HVMCs) presents a greater puzzle, because they are much denser and more massive. If the HVMCs were accelerated by the strong activities in the Galactic centre, they are expected to be destroyed before they reach such a high velocity. To shed light on this phenomenon, we perform 3D numerical simulations to investigate the origin and hydrodynamic evolution of HVMCs during a starburst in the Galactic centre. We find that the presence of a magnetic field provides effective protection and acceleration to molecular clouds (MCs) within the galactic winds. Consequently, the MCs can attain latitudes of approximately 1 kpc with velocities around 200 km s−1, consistent with the observed characteristics of HVMCs. The consistency of our findings across a wide parameter space supports the conclusion that HVMCs can indeed withstand the starburst environment in the Galactic centre, providing valuable insights into their survival mechanisms. [ABSTRACT FROM AUTHOR]

We present the results of direct-method metallicity measurements in the disc and outflow of the low-metallicity starburst galaxy NGC 1569. We use Keck Cosmic Web Imager observations to map the galaxy across 54″ (800 pc) along the major axis and 48″ (700 pc) along the minor axis with a spatial resolution of 1″ (∼15 pc). We detect common strong emission lines ([O  iii ] λ5007, H β, [O  ii ] λ3727) and the fainter [O  iii ] λ4363 auroral line, which allows us to measure electron temperature (Te) and metallicity. Theory suggests that outflows drive metals out of the disc driving observed trends between stellar mass and gas-phase metallicity. Our main result is that the metallicity in the outflow is similar to that of the disc, Z out/ Z ISM ≈ 1. This is consistent with previous absorption line studies in higher mass galaxies. Assumption of a mass-loading factor of |$\dot{M}_{\rm out}/{\rm SFR}\sim 3$| makes the metal-loading of NGC 1569 consistent with expectations derived from the mass–metallicity relationship. Our high spatial resolution metallicity maps reveal a region around a supermassive star cluster (SSC-B) with distinctly higher metallicity and higher electron density, compared to the disc. Given the known properties of SSC-B the higher metallicity and density of this region are likely the result of star formation-driven feedback acting on the local scale. Overall, our results are consistent with the picture in which metal-enriched winds pollute the circumgalactic medium surrounding galaxies, and thus connect the small-scale feedback processes to large-scale properties of galaxy haloes. [ABSTRACT FROM AUTHOR]