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Old February 22nd 17, 08:03 PM posted to sci.astro.research
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Default Galactic Bar Formation?

It's been a while since I've explored this topic. Years ago no one
had posited this model and I was told it was wrong. I thought I'd
check if anything has changed since.

Has anyone posited the following model for creating a galactic bar?

Two galaxies merge. A pair of massive black holes (and stars)
become trapped in orbit at some kpc separation (the ends of the
bar).

A bar of stars forms between them, probably having orbits that
are co rotating and longitudinal. In a frame rotating with the
forming bar, it would appear the stars are moving essentially
along a line within the bar.

At some point enough stars are within the bar that the gravity of
the stars between the BH's causes the massive black holes to slide
down the bar to the center, where they orbit and merge.

We see the bar and we see a line of dust down each bar, that curves
into what appears to be a circular trajectory near the center.

See: https://en.wikipedia.org/wiki/Barred_spiral_galaxy

to see the dust lanes.

Any aspects matching (or refuting) this model been observed?

Thanks,

rt

[[Mod. note -- One big problem with this model is that massive black
holes aren't massive enough to dominate the stellar dynamics at kiloparsec
(= galactic-bar-size) distances. That is, on the size scale of a galactic
bar, even a "supermassive" black hole is still only a tiny fraction of
the mass in stars, interstellar gas/dust, and maybe dark matter.
-- jt]]