<p>As it can be seen from Plank 2018 Cosmic Microwave Background <a href="https://www.aanda.org/articles/aa/full_html/2020/09/aa33910-18/F1.html" rel="nofollow noreferrer">temperature fluctuations</a> data-</p>
<p><a href="https://i.sstatic.net/Czp2B.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Czp2B.png" alt="enter image description here" /></a></p>
<p>There are 3 sharp peaks at multipole expansions <span class="math-container">$\ell \approx 250, 550, 800 $</span>. Also as multipole expansion goes on and adds more details to angular sensitivity of temperature fluctuations,- these fluctuations are damped-down almost exponentially. First question would be,- Why there are exactly 3 sharp peaks of CMB temperature fluctuations and what they are mapped to with respect to universe evolution timeline / structures/matter formation ? Are these peaks somehow related to the fact that universe is composed of ordinary matter, dark matter and dark energy, or this is irrelevant information ? And second question would be Why temperature fluctuations are decreased almost exponentially as multipole expansion goes on ? Thanks.</p>

CC BY-SA 4.0
2022-05-31T07:49:55.680Z
I’m no cosmologist and my understanding is limited, but here’s what I remember from my undergraduate cosmology class: first peak location on x axis is related to curvature of the universe, location of first peak on y axis is related to total mass density ($\Omega_M$), second peak y axis location related to baryonic matter (higher y value means less baryonic matter) and third peak y axis is related to dark matter amount. I have some very nice graphs illustrating this from my notes, but I have no idea what the source material is for it, that said I can share if you’re interested.
Justin T
CC BY-SA 4.0
2022-05-31T07:54:45.583Z
I would also add that I remember distinctly my professor saying this structure is some of the most compelling evidence we have for dark energy/ matter
Justin T
CC BY-SA 4.0
2022-05-31T09:31:13.097Z
Thanks, Can you expand on this in a bit more detailed version posting it in your answer ?
Agnius Vasiliauskas
<astrophysics><temperature><formation><cosmic-microwave-background>
Explanation for Planck 2018 temperature fluctuations strongest peaks
Agnius Vasiliauskas
# Explanation for Planck 2018 temperature fluctuations strongest peaks

(Asked by: username_0 on 2022-05-30)

As it can be seen from Plank 2018 Cosmic Microwave Background [temperature fluctuations](https://www.aanda.org/articles/aa/full_html/2020/09/aa33910-18/F1.html) data-

[![enter image description here](https://i.sstatic.net/Czp2B.png)](https://i.sstatic.net/Czp2B.png)

There are 3 sharp peaks at multipole expansions $\ell \approx 250, 550, 800 $. Also as multipole expansion goes on and adds more details to angular sensitivity of temperature fluctuations,- these fluctuations are damped-down almost exponentially. First question would be,- Why there are exactly 3 sharp peaks of CMB temperature fluctuations and what they are mapped to with respect to universe evolution timeline / structures/matter formation ? Are these peaks somehow related to the fact that universe is composed of ordinary matter, dark matter and dark energy, or this is irrelevant information ? And second question would be Why temperature fluctuations are decreased almost exponentially as multipole expansion goes on ? Thanks.

**Tags:** astrophysics, temperature, formation, cosmic-microwave-background

> **Comments:**
> **username_1**: I’m no cosmologist and my understanding is limited, but here’s what I remember from my undergraduate cosmology class: first peak location on x axis is related to curvature of the universe, location of first peak on y axis is related to total mass density ($\Omega_M$), second peak y axis location related to baryonic matter (higher y value means less baryonic matter) and third peak y axis is related to dark matter amount. I have some very nice graphs illustrating this from my notes, but I have no idea what the source material is for it, that said I can share if you’re interested.  
> **username_1**: I would also add that I remember distinctly my professor saying this structure is some of the most compelling evidence we have for dark energy/ matter  
> **username_0**: Thanks, Can you expand on this in a bit more detailed version posting it in your answer ?  

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## 0 answers

