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enter image description here

I am referring to this picture published here. Apparently super massive black holes emit radiation and matter in astrophysical jets. And these jets can form galaxies. I have some questions:

  1. Isn't throwing out matter contrary to what a black hole is supposed to do? I imagine that the collapsing stars and gas falling into black hole would get super-heated and would emit energy as radiation but why would it throw out matter?

  2. The matter is said to leave at near speed of light. Can such fast moving jet condense to form a galaxy? If it does, shouldn't it be a stretched, thin thread like structure and not a Spiral galaxy as shown in the illustration?

Kshitiz Sharma
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1 Answers1

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  1. No, throwing matter out isn't contrary to a BH; there is often an accretion disc surrounding the black hole and that is what forms the jet.
  2. No, the ejected material cannot condense to form a galaxy. A galaxy requires the material to be gravitationally bound to some central point, a jet moving at $\sim c$ is moving too fast to be gravitationally bound to anything.

As to the shape of the jet, it should be a stream, as evidenced by the Hubble Space Telescope image of Messier 87 (M87): enter image description here

but this is nowhere near the spiral shape of a galaxy.

The artist's impression of the situation is to show that the jet (the bright object in the upper left) from the black hole is illuminating a nearby galaxy (the object towards the right of your image). What researchers have further found is that the particular quasar, called HE0450-2958, appears to be inducing a high star formation rate in a nearby galaxy--a rate of about 100 times what is found in the Milky Way! It is based on this that the (likely misleading) title of the article Black Hole Caught Zapping Galaxy into Existence? is given.

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Kyle Kanos
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