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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?

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    $\begingroup$ Link to the original story (or better still, a journal paper) - it is impossible to write a sensible commentary on some artists impression. I almost guarantee that the astronomers will not have said anything is "zapping" something "into existence". $\endgroup$
    – ProfRob
    Dec 2, 2014 at 15:00
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    $\begingroup$ Original story: eso.org/public/news/eso0946 $\endgroup$
    – safesphere
    Nov 24, 2019 at 17:42

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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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  • $\begingroup$ While I believe that your answer correctly identifies the subject matter which inspired the artist commissioned by the European Southern Observatory (on Nov. 30, 2009) as having been photographs made thru the Hubble telescope, I'd still guess that my own identifies the artist's treatment of that subject matter, as evinced by the ESO's surprisingly zany heading for its article. $\endgroup$
    – Edouard
    Nov 24, 2019 at 11:02
  • $\begingroup$ Re your point on the last of the OP's two secondary questions, vis-a-vis the ESO's press release at eso.org/public/news/eso0946, do you feel it likelier that its astrophysicists made some computational errors re "escape velocity" as described in the Wikipedia link you've made, or that you yourself might not have taken adequate account of such details as the effect of whatever media the plasma jet might've been traversing on the velocity of its particles, with respect to the condensation which Kshitiz Sharma had been considering as a possibility? $\endgroup$
    – Edouard
    Nov 26, 2019 at 7:02

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