In article , jacobnavia
writes:

Heavy stars are produced by the galaxy, converting cold gas into black
holes or heavy neutron stars.

Supernova explosions aren't symmetric, most stars receive a "kick" when
transforming into a black hole or a neutron star.

As eons pass, the dead stars accumulate either at the center of the
galaxy or in a diffuse halo of invisible matter around the galaxy.

This invisible mass can't explain the sorely needed black matter?

No, since it would mean a baryonic density higher than that obtained by
other arguments. Also, such a population would be detectable via
microlensing.

Couldn't a symmetrical population of dead and invisible halo stars make
for the modified gravity we see?

No; see above.

[[Mod. note -- These black holes are more massive than most stars,
so dynamical friction (
https://en.wikipedia.org/wiki/Dynami...uitive_account
) causes them to gradually sink towards the center of the galaxy.
This means that there may be a high density of black holes near the
center of the galaxy. But, because these black holes are concentrated
at the center of the galactic, they can't explain flat galaxy rotation
curves. To explain those (without MOND) dark matter must be widely
distributed throughout the galaxy.
-- jt]]

Right. Actually, to explain flat rotation curves with dark matter, most
of the dark matter must be outside the visible galaxy.