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Let say we are talking about our Milky way and Sagittarius A* emitted a astrophysical jet. If the galaxy was 150 000 ly wide would its gravity with dark matter included eventually slow down that jet keeping in mind that gravity of a disk loses strength slower than a sphere as a black hole is?

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    $\begingroup$ Anything at all will slow down anything else at all, by gravitational attraction, if they are initially moving apart. So the answer is yes. But perhaps you are looking for a more thorough answer, with order-of-magnitude estimates or something like that. If so, then maybe make the question a bit more descriptive, to state more fully what you want to find out. $\endgroup$ Dec 27, 2020 at 14:03
  • $\begingroup$ @AndrewSteane Can this be a result of astr.jets sciencenewsforstudents.org/article/… $\endgroup$ Dec 27, 2020 at 22:31

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No.

These jets are jets because they are faster than the escape speed of the various relevant objects (central black hole / Active Galactic Nucleus / host galaxy). Thus, gravity is not relevant in slowing it down. For order of magnitude, the escape speed of the Milky Way galaxy is about 650km/s, but these jets are relativistic, i.e. one or two orders of magnitude faster.

Instead, jets are slowed down by Ram pressure as they encounter the intergalactic gas. This is why they "puff up" (rather than fall back on a parabolic orbit). Classic example is the jet from M87:

enter image description here

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