Editing Talk:2853: Redshift
Please sign your posts with ~~~~ |
Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.
The edit can be undone.
Please check the comparison below to verify that this is what you want to do, and then save the changes below to finish undoing the edit.
Latest revision | Your text | ||
Line 62: | Line 62: | ||
</nowiki></pre></tt> | </nowiki></pre></tt> | ||
− | And should you wish to make [https://i.ibb.co/ | + | And should you wish to make [https://i.ibb.co/kK21n1J/time-by-redshift.png this quick reference chart for interpreting observations in the JWST era:] |
{{cot|Supplemental code for Look-back Time by Redshift chart}} | {{cot|Supplemental code for Look-back Time by Redshift chart}} | ||
Line 69: | Line 69: | ||
import matplotlib.ticker as ticker | import matplotlib.ticker as ticker | ||
− | + | redshifts = [z * 20 / 299 for z in range(300)] # 0 to 20 in 300 steps | |
− | + | look_back_times = [zt(z) for z in redshifts] | |
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
+ | plt.plot(redshifts, look_back_times) | ||
plt.title('Look-back Time by Redshift') | plt.title('Look-back Time by Redshift') | ||
plt.xlabel('z: (observed λ - expected λ) / expected λ') | plt.xlabel('z: (observed λ - expected λ) / expected λ') | ||
Line 84: | Line 78: | ||
plt.xticks(range(21)) | plt.xticks(range(21)) | ||
plt.yticks(list(range(14)) + [age0]) | plt.yticks(list(range(14)) + [age0]) | ||
− | plt.text(-0.5, 13.78, "Big Bang", va='center') | + | plt.text(-0.5, 13.78, "Big Bang", ha='left', va='center') |
plt.gca().yaxis.set_major_formatter(ticker.FormatStrFormatter('%.1f')) | plt.gca().yaxis.set_major_formatter(ticker.FormatStrFormatter('%.1f')) | ||
plt.grid(True, color='lightgray') | plt.grid(True, color='lightgray') | ||
Line 91: | Line 85: | ||
for t in range(0, 13): | for t in range(0, 13): | ||
− | z = | + | z = redshifts[min(range(len(look_back_times)), |
+ | key=lambda i: abs(look_back_times[i]-t))] | ||
plt.text(z, t, f" z = {z:.2f}", ha='left', va='center', fontsize='small') | plt.text(z, t, f" z = {z:.2f}", ha='left', va='center', fontsize='small') | ||
Line 103: | Line 98: | ||
plt.savefig('time_by_redshift.png', bbox_inches='tight') | plt.savefig('time_by_redshift.png', bbox_inches='tight') | ||
− | #plt.show() # https://i.ibb.co/ | + | #plt.show() # https://i.ibb.co/kK21n1J/time-by-redshift.png |
</nowiki></pre></tt> | </nowiki></pre></tt> | ||
{{cob}} | {{cob}} | ||
− | Or [https://i.ibb.co/ | + | Or [https://i.ibb.co/34Rk2WM/age-by-redshift.png this one showing the age of the universe from redshift:] |
{{cot|Supplemental code for Age of Universe by Redshift chart}} | {{cot|Supplemental code for Age of Universe by Redshift chart}} | ||
<tt><pre><nowiki> | <tt><pre><nowiki> | ||
− | plt.clf() # | + | plt.clf() # reset plot |
− | |||
− | |||
− | |||
− | + | redshifts = [z * 15 / 299 + 5 for z in range(300)] # 5 to 20 in 300 steps | |
− | + | ages = [age_at_z(z) * 1000 for z in redshifts] # Gyr to million years | |
− | |||
− | |||
+ | plt.plot(redshifts, ages) | ||
plt.title('Age of Universe by Redshift') | plt.title('Age of Universe by Redshift') | ||
plt.xlabel('z: (observed λ - expected λ) / expected λ') | plt.xlabel('z: (observed λ - expected λ) / expected λ') | ||
Line 131: | Line 122: | ||
plt.savefig('age_by_redshift.png', bbox_inches='tight') | plt.savefig('age_by_redshift.png', bbox_inches='tight') | ||
− | #plt.show() # https://i.ibb.co/ | + | #plt.show() # https://i.ibb.co/34Rk2WM/age-by-redshift.png |
</nowiki></pre></tt> | </nowiki></pre></tt> | ||
{{cob}} | {{cob}} |