<p>Redshifts are plotted because usually that is all that can be <em>measured</em>.</p>
<p>Other quantities could be plotted, but since these are <em>inferred</em> from the redshift itself (e.g. density would just mean plotting <span class="math-container">$(1+z)^3$</span>), or would need to assume particular cosmological models or parameters (e.g. if you plotted look-back time), then it makes sense to stick with plotting the observed data.</p>

CC BY-SA 4.0
2020-12-03T08:16:17.493Z
2020-12-03T08:16:17.493Z
ProfRob
<p>Why do astrophysicists often use redshift in plots? Why it is important to know how an astrophysical object evolves in function of redshift? I was seeing an &quot;cosmological time per redshift galaxies formation plot&quot; and thinking why redshift and not, who knows, density?</p>

CC BY-SA 4.0
2020-12-02T19:53:30.853Z
I'm voting to close this question because it needs more focus. Perhaps ask these "sub-questions" in new ones?
WarpPrime
<astrophysics><redshift>
redshift in astrophysical plots
Anderson Costa
# redshift in astrophysical plots

(Asked by: username_0 on 2020-12-02)

Why do astrophysicists often use redshift in plots? Why it is important to know how an astrophysical object evolves in function of redshift? I was seeing an "cosmological time per redshift galaxies formation plot" and thinking why redshift and not, who knows, density?

**Tags:** astrophysics, redshift
> **Comments:**
> **username_1**: I'm voting to close this question because it needs more focus. Perhaps ask these "sub-questions" in new ones?  

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## 1 answers

### Answer by username_2 on 2020-12-03. Score: 3

Redshifts are plotted because usually that is all that can be *measured*.

Other quantities could be plotted, but since these are *inferred* from the redshift itself (e.g. density would just mean plotting $(1+z)^3$), or would need to assume particular cosmological models or parameters (e.g. if you plotted look-back time), then it makes sense to stick with plotting the observed data.


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