Understanding Void effects on the Hubble constant

[Arman777]

Its proposed that Voids can solve the Hubble Tension but later on with detailed studies its shown that, its not possible. And I am reading an online site and I saw a nice graph but I am troubling to understand it.

https://aasnova.org/2019/03/05/can-we-a-void-the-hubble-tension-with-local-voids/

What is $z_{split}$ ? The author tries to explain it but its not so good.

For a detailed discussion : https://arxiv.org/abs/1901.08681

 

[AndyW]

Hello,

First of all, thank you for bringing up this topic. The "Hubble Tension" is a hotly debated topic in the scientific community and it's always interesting to see new theories and studies being proposed.

To answer your question, $z_{split}$ refers to the redshift at which the expansion rate of the Universe begins to deviate from the expected value based on the cosmic microwave background (CMB) measurements. This deviation is what is causing the Hubble Tension.

In the article you mentioned, the author proposes that the presence of local voids (regions of lower matter density) could explain this deviation and thus solve the Hubble Tension. However, as you mentioned, further studies have shown that this is not a viable solution. In fact, recent studies have shown that the presence of local voids actually exacerbates the Hubble Tension rather than solving it.

I would recommend reading the detailed discussion in the linked arXiv paper for a better understanding of the concept and the current debates surrounding it. As scientists, it's important for us to constantly question and evaluate our theories in order to reach a deeper understanding of the Universe.

I hope this helps clarify the concept of $z_{split}$ and the proposed solution for the Hubble Tension. Keep exploring and questioning!