AFAIK, objects in the universe thought to be black holes show evidence of radiatively inefficient accretion flow. But is this the case with Quasars? If not, is there a possibility that the core of a quasar is an object similar to a neutron star.

  • $\begingroup$ The properties of the accretion flow are more a function of the environment than that of the compact object. So I think you're not comparing apples and apples here. $\endgroup$ Jan 19, 2018 at 5:17
  • $\begingroup$ @AtmosphericPrisonEscape: However, when there is a compact object present the infalling matter strikes the surface and results in intense bursts of radiation that can exceed the Eddington limit. Whereas with an event horizon the radiation released is well below the Eddington limit because much of that energy is being sucked into a black hole. $\endgroup$ Jan 19, 2018 at 6:55
  • $\begingroup$ You should be right with that. I think the argument for the 'central engine' of a quasar to be a black hole were something something relativity. I'll look it up later if I have time. Else you can google for the central engine, that's the keyword in that field. $\endgroup$ Jan 19, 2018 at 12:58

1 Answer 1


The solution to your question is surprisingly simple, I think:

A quasar that puts out energy around Eddington luminosity or higher, must accrete at a certain rate, corresponding to the energy output.

When consulting a lecture and a random paper from the archive on this topic, it is evident that those accretion rates correspond to 1-10 solar masses per year or higher. A neutron star accreting 1-10 solar masses in one year will become a very massive black hole quickly enough.


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