Submit that the effluence of SgrA*, during past AGN phases, contributes the bulk of the material which is now coalescing into these star forming regions.
Do we have a coherent theory of material circulation processes in spiral galaxies?
Looking at the spiral, it is not hard to imagine that material is flowing toward the center, and due to the conservation of angular momentum, it orbits more rapidly around the center as it gets drawn in. But, that doesn't explain the "bars" that form across the center.
Thinking about how material ejected from a central supermassive black hole, exiting perpendicular to the galactic plane, gets back to the galactic plane, I am not seeing simple mass and momentum principles that work out that way. Are there magnetic fields that are being followed by ionized matter after it is ejected?
And, regarding the issue raised in the article about why protoplanetary disks do not last as long in these distant star-forming regions, I am wondering if that has something to do with the observed low concentrations of "metals", which are necessary to create "dust". Without much "dust" in the disks, it seems that they would be more quickly dissipated by "stellar wind" once the star ignites fusion in its core.
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