Ancient galaxies: lack of mergers vs. subsequent spatial expansion

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In summary, the study of ancient galaxies highlights the contrast between the absence of mergers during their formation and the impact of subsequent spatial expansion on their evolution. While mergers are commonly thought to drive galactic growth and complexity, the lack of such interactions in early galaxies suggests that other factors, including the dynamics of cosmic expansion, played a significant role in shaping their structures and distributions over time. This understanding challenges traditional views of galaxy formation and emphasizes the importance of considering the broader cosmic context.
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Has anyone had success in disentangling the phenomenon of galaxy mergers from that of spatial expansion in explaining the fact that distant galaxies are closer together?
Galaxies far away---that evolved soon after the Big Bang---are reported to be closer together than the galaxies we observe near us. This could be due to two distinct reasons. One is that relatively nearby galaxies, over time, tend to merge, and the ones we see from far away haven't had time to coalesce yet. The other reason is that the assumed spatial expansion of Big Bang Theory hadn't yet had time to separate those galaxies. Have any cosmologists succeeded in distinguishing these two possibilities?
 
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The fact that galaxies in the past were closer together isn't something we would have determined observationally, but something that follows from the expansion of the universe.
 
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I think I read a recent (and not definitive) article about observations from the James Webb Space Telescope, dealing somewhat with the issue (maybe in Nature or Nature Astronomy). I'll see if I can track it down.
 
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hkyriazi said:
I think I read a recent (and not definitive) article about observations from the James Webb Space Telescope, dealing somewhat with the issue (maybe in Nature or Nature Astronomy). I'll see if I can track it down.
If that is so, in effect, it could be just one more of the millions of fulfilled predictions of the Big Bang theory, as well as any other exotic thing that comes to mind.
 
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"I think I read somewhere" is hard to follow up on. I would hope that the article defines what "closer" means in an infinite universe where galaxies clump on multiple scales so we're all talking about the same thing.
 
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hkyriazi said:
Galaxies far away---that evolved soon after the Big Bang---are reported to be closer together than the galaxies we observe near us.
Reported where? As has already been commented, you need to give a specific reference. Otherwise we don't have a valid basis for discussion.
 
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FAQ: Ancient galaxies: lack of mergers vs. subsequent spatial expansion

What are ancient galaxies?

Ancient galaxies are galaxies that formed in the early universe, typically within the first billion years after the Big Bang. They provide crucial information about the conditions and processes that prevailed in the early cosmos.

What is meant by "lack of mergers" in the context of ancient galaxies?

The "lack of mergers" refers to the observation that some ancient galaxies appear to have formed and evolved with minimal interaction or merging with other galaxies. This is in contrast to the hierarchical model of galaxy formation, which suggests that galaxies grow primarily through mergers and accretion of smaller systems.

How does subsequent spatial expansion affect ancient galaxies?

Subsequent spatial expansion, driven by the overall expansion of the universe, affects ancient galaxies by increasing the distances between them over time. This cosmic expansion can influence their observed properties, such as their size and redshift, and can also affect the likelihood of interactions and mergers.

Why is it significant to study the lack of mergers in ancient galaxies?

Studying the lack of mergers in ancient galaxies is significant because it challenges existing models of galaxy formation and evolution. Understanding why some galaxies have evolved with minimal mergers can provide new insights into the processes that govern galaxy growth and the conditions of the early universe.

What methods are used to study ancient galaxies and their merger histories?

Astronomers use a variety of methods to study ancient galaxies and their merger histories, including deep-field observations with telescopes like the Hubble Space Telescope and the James Webb Space Telescope, spectroscopy to analyze the light from these galaxies, and computer simulations to model galaxy formation and evolution. These methods help to reconstruct the history and properties of ancient galaxies.

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