On the homepage of the galaxies research group at CfA SAO, it states, "Astronomers discovered that as many as 25% of galaxies are currently merging with others." They do not provide a reference for this statement. I'm wondering what scientific articles demonstrate this expectation?

More specifically, is this expectation purely based on theoretical calculations from e.g. cosmological simulations of the Universe, or is it motivated from observations of merging galaxies?

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    $\begingroup$ This paper from galaxy zoo has quite different numbers. From a collection of 304,182 potential target galaxies, they obtained 3003 that were clearly merging pairs or groups of galaxies. (ie 1%, or perhaps 2% if you count each merging pair as two galaxies) Their method was intended to avoid false positives, nevertheless, far few than 25% of their galaxies were merging arxiv.org/pdf/0903.4937.pdf $\endgroup$
    – James K
    Nov 14, 2022 at 19:48
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    $\begingroup$ Presumably you can boost the percentage by considering very minor mergers, like the Milky Way and some of its very low mass dwarf companions. These wouldn’t be visible in Galaxy Zoo images. (The paper JamesK links to mentions mergers where the masses of the two galaxies differ by less than a factor of three.) $\endgroup$ Nov 14, 2022 at 22:22


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