Astronomy & space · Advanced university
Scale factor from cosmological redshift · formula reference
Apply the homogeneous expanding-universe cosmological-redshift model, not a local Doppler shift.
Formula
Apply the homogeneous expanding-universe cosmological-redshift model, not a local Doppler shift.
aemit/anow = 1/(1+z)
Worked example
In a cosmological expansion model, a source has redshift 5.4. Find aemit/anow. Round the final result to 4 decimal places if needed.
The ratio is the reciprocal of 1+5.4.
0.1563
Prerequisites and checking
Algebra and the topic definitions. Keep units and rounding consistent. State the model conditions before applying the formula.
Further reading and review references
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