Well, black holes aren't portals to some other place in the cosmos, but they are a kind of "wormhole". Not in some unique sense, though, nor in the way that we think of wormholes; but everything is a "wormhole" in its own right. For example, the Earth pulls infinitesimal particles around it by its force of gravity which then travel physically through it and out the other side in a sort of "wormhole" kind of way. Those that come out the other side and are still stuck in its gravity are bent back inward over time and travel in a Figure-8 orbital which then arises in what we see as Earth's electromagnetic field. This is how gravity can be shown to produce electromagnetism, in general, due to the ability of smaller particles to physically pass through larger ones (such as neutrinos being known to pass through the Earth). Any electromagnetic field is the result of this type of "wormhole" for smaller particles flowing through larger particles by gravity. Again, though, it isn't the same concept of "wormhole" that we propose, where it is essentially a portal to some other location in the cosmos.

If we are small enough relative to a black hole, we could also theoretically pass through a black hole but we wouldn't come out at some other physical location in the universe, we would come out the other side of the body just the same. Even if our atoms could make the journey without physically colliding with the "atoms" of the black hole (think of it as a planet composed of what we call 'solar systems' as its 'atoms') we would still be in the extremely high temperatures and pressures that would be present which would not be pleasant.

Black hole emissions are no different than a star's emissions; they are a function of its mass. Larger masses emit larger mass systems, but they are still ultimately components of the system that are radiated outward and aren't originating from some other location in the universe (through a wormhole).

I write a bit more about black holes in other posts, such as What is a Black Hole? and The Truth About Black Holes, if you'd like to check them out. Most my interpretations largely build off of the concept that the universe is infinite and that gravity causes everything, though. The Big Bang's Big Assumption goes through many critical observations and really explains why gravity, the only fundamental force in the universe, causes them. There is a lot to it, if you are interested I have written many articles here on Steemit that go into extensive detail on it all.

Thanks for reading, commenting, and liking the article! Hope my answer made some sense and that you check out other posts of mine for more exposure to it all. :)

-Steve