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I've been saying "some". I can't find a reference for a particular percentage.

This seems to address the question to some extent; https://arxiv.org/abs/astro-ph/0108389 would "roughly 1%" be in the right ballpark for an answer then?

pesa points out this is redshift-dependent. I am looking for a ballpark figure of the fraction of AGN at $z < 1$.

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  • $\begingroup$ don't let my hat scare you, it's "hat season" here. I added some minimal research to your question; "I looked and didn't find anything" is not a good way to elicit good quality answers, it's better to add at least a little evidence of research to a question. Welcome to Stack Exchange! $\endgroup$
    – uhoh
    Dec 9 '19 at 12:45
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    $\begingroup$ Hi Sean, the answer to your question is highly redshift-dependent. AGN activity peaked around z ~ 2, while earlier and later epochs have significantly smaller fractions. If you mean "today" (i.e. z = 0), you should probably add that information to your question. $\endgroup$
    – pela
    Dec 9 '19 at 14:10
  • $\begingroup$ That's true. The number I'm probably after is AGN fraction integrated from z = 0 to z = ~0.7. $\endgroup$ Dec 9 '19 at 14:16
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    $\begingroup$ Note that the paper you link to is about the fraction of z ~ 0 galaxies with "Seyfert 1" nuclei, which are not the only type of AGN. So that should be considered a lower limit. $\endgroup$ Jan 12 '20 at 12:30
  • $\begingroup$ In addition to the redshift dependence, there is also a strong dependence on stellar mass (more massive galaxies are more likely to host AGN). $\endgroup$ Jan 12 '20 at 12:46
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As Pela said in the comment, it is highly redshift dependent so there is no straight answer. "Some" is the safest option.

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