<p>On the <a href="https://pweb.cfa.harvard.edu/research/topic/galaxies-merging-and-interacting" rel="noreferrer">homepage</a> of the galaxies research group at CfA SAO, it states, &quot;Astronomers discovered that as many as 25% of galaxies are currently merging with others.&quot; They do not provide a reference for this statement. I'm wondering what scientific articles demonstrate this expectation?</p>
<p>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?</p>

CC BY-SA 4.0
2022-11-14T19:48:22.010Z
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  https://arxiv.org/pdf/0903.4937.pdf
James K
CC BY-SA 4.0
2022-11-14T22:22:12.773Z
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.)
Peter Erwin
<galaxy><galactic-dynamics><galaxy-cluster><galactic-evolution>
How many galaxies are currently merging?
Daddy Kropotkin
# How many galaxies are currently merging?

(Asked by: username_0 on 2022-11-14)

On the [homepage](https://pweb.cfa.harvard.edu/research/topic/galaxies-merging-and-interacting) 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?

**Tags:** galaxy, galactic-dynamics, galaxy-cluster, galactic-evolution

> **Comments:**
> **username_1**: 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  https://arxiv.org/pdf/0903.4937.pdf  
> **username_2**: 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.)  

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## 0 answers

