Double-A wrote:
I thought you said that gamma ray bursts were caused by black holes
reaching their "critical mass"?

Known experiments on earth show that gamma bursts come from chain
reaction fission (aka "the bomb"). Environmentally induced fusion
processes (e.g. old sol) can also produce gammas, but they would be
steady state and not transient bursts. "Bomb" fusion produce gamma
bursts, but they requires a hot-cold environment to the best of our
knowledge, which I say is not natural (baked alaska is man-made).

Black holes, or any other accumulation, can become critical, I suppose,
but we need a very well thought out scenario to make it credible.

Then how come we don't observe any white holes, or white hole
candidates?

White holes as you infer, may only be accumulations that have not yet
become large enough to create an event horizon (where photon emissions
from the star can't get past).

There are gamma rays, yes, but we can't see what kind of
object they are coming from because they come from outside our galaxy.

I don't know how to interpret that thought.

I'm staying with the bow tie nebula concept where breakdown fission is
the energetic event.

Angelo Campanella