How many parsecs is it when the redshift z=1

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Discussion Overview

The discussion revolves around the conversion of redshift (z) to parsecs, specifically addressing the case when z=1. Participants explore different methods and equations for this conversion, highlighting the dependence on various concepts of distance.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • Some participants inquire about a simple equation to convert redshift to parsecs, indicating a desire for clarity on the conversion process.
  • It is noted that the conversion depends on the concept of distance used, with references to additional materials that elaborate on this dependency.
  • One participant mentions using a lightcone calculator and provides specific parameters and results related to cosmological distances, suggesting a method for obtaining the desired conversion.
  • Another participant expresses appreciation for the quality of the information shared, indicating that they found the discussion helpful.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a single method for conversion, as the discussion reflects multiple approaches and acknowledges the complexity of the topic.

Contextual Notes

The discussion highlights the need for clarity regarding the definitions of distance in cosmology, as well as the potential variations in results based on different parameters used in calculations.

nenyan
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How to convert red shift to parsecs? Is there a simple converting equation?
 
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nenyan said:
How to convert red shift to parsecs?

This depends on which concept of distance is used. See the first paragraph of the attached file.

nenyan said:
s there a simple converting equation?

I wrote up an answer for someone else, who specified z = 0.4. I didn't use dimensionless parameters. See the last two graphs in the attached file.
 

Attachments

very useful. thanks
 
George Jones said:
This depends on which concept of distance is used. See the first paragraph of the attached file.



I wrote up an answer for someone else, who specified z = 0.4. I didn't use dimensionless parameters. See the last two graphs in the attached file.

thats one of the better quality articles I've read. Far better than some of my attempts lol. Thank you for showing it.
 
My signature first link has a handy tool called the lightcone calculator here I set stretch to 2.0 for S_upper. S=1+z. I set a randon value for lower stretch.
then I selected the columns I wanted and decimal places. Clicked linear steps.
here is the result with WMAP
flat geometry parameters.

{\small\begin{array}{|c|c|c|c|c|c|}\hline R_{0} (Gly) & R_{\infty} (Gly) & S_{eq} & H_{0} & \Omega_\Lambda & \Omega_m\\ \hline 14.4&17.3&3400&67.9&0.693&0.307\\ \hline \end{array}} {\small\begin{array}{|r|r|r|r|r|r|r|r|r|r|r|r|r|r|r|r|} \hline a=1/S&S&z&T (Gy)&D_{now} (Gly)&D_{then}(Gly) \\ \hline 0.500&2.000&1.000&5.8636&11.046&5.523\\ \hline 1.000&1.000&0.000&13.7872&0.000&0.000\\ \hline 1.668&0.599&-0.401&21.7987&6.249&10.425\\ \hline 2.783&0.359&-0.641&30.4437&10.300&28.660\\ \hline 4.642&0.215&-0.785&39.2497&12.776&59.303\\ \hline 7.743&0.129&-0.871&48.0918&14.267&110.467\\ \hline 12.915&0.077&-0.923&56.9418&15.162&195.824\\ \hline 21.544&0.046&-0.954&65.7934&15.698&338.212\\ \hline 35.938&0.028&-0.972&74.6452&16.020&575.729\\ \hline 59.948&0.017&-0.983&83.4973&16.213&971.932\\ \hline 100.000&0.010&-0.990&92.3494&16.328&1632.838\\ \hline \end{array}}

the top row has the result you want you just need to convert to parsecs.
 

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