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Has the Lyman-alpha forest ever been used to test Halton Arp's theory that quasars are not cosmological but instead are ejected from relatively near-by galaxies? If Arp was right, then the spectra of the quasar and the 'parent galaxy' should both show the same Lyman-alpha forest; if it only appears in the quasar spectra, then the quasar must be much further away.

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  • $\begingroup$ By "parent galaxy", do you mean not the galaxy that hosts the quasar, but rather a galaxy that is nearby in projected distance but not in redshift? $\endgroup$
    – pela
    Apr 21, 2017 at 19:52
  • $\begingroup$ Also, "relatively nearby galaxies" do not really show any Ly$\alpha$ forest since the Universe is completely ionized. A clear evolution in the Ly$\alpha$ forest is seen in quasar spectra. But arguably a more robust evidence for the cosmological nature of quasars is the redshift of their emission lines. $\endgroup$
    – pela
    Apr 21, 2017 at 19:59
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    $\begingroup$ It is a concern here that google throws up a load of creationist nonsense associated with this question. $\endgroup$
    – ProfRob
    Apr 21, 2017 at 20:10
  • $\begingroup$ Yes, by 'parent galaxy' I meant the nearby galaxy with a lower redshift that, according to Arp, ejected the quasar. $\endgroup$ Apr 21, 2017 at 22:17
  • $\begingroup$ "It is a concern here that google throws up a load of creationist nonsense associated with this question." Yes, and it would be nice to be able to shoot them down by pointing to such a measurement that showed Ly-alpha in the quasar's spectra but not in the supposed 'parent galaxy'. $\endgroup$ Apr 25, 2017 at 2:52

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All possible tests of the Arp model have been failed. High redshift quasars have Lyman alpha forests, low redshift galaxies do not.

The Arp model suggests that the Lyman alpha forests are somehow intrinsic to the quasar. There are many problems with this idea.

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