Type one A super novas come from binary stars when one star is a white dwarf and has a runaway nuke explosion with matter from the other star.
The umbrella galaxy is a red giant and a white dwarf where the white dwarf explodes only partially. Depending on the elderly stars in a binary system, they can do unexpected things. Neutron binary stars warp gravity. Binary black holes combine to make bigger black holes and ripples the universe for billions of light years. Some super massive black holes are mysteriously big at the early universe.
How did they grow ?
We just don't know.