A distant galaxy is observed at a redshift of 0.26. At the time the light was em

Question

A distant galaxy is observed at a redshift of 0.26. At the time the light was emitted from this galaxy, the temperature of the CMB was: 0.7 K 3.4 K 4.3 K 5.4 K 11.7 K What was the energy density of photons in the universe at z = 0.26 compared to the present day density? 0.26 times as dense. 1.26 times as dense. 1.6 times as dense (no change). 2.0 times as dense. 2.5 times as dense A civilization living at some other time in the history of universe measures that the CMB spectrum peaks at a wavelength of 0.763 mm. What redshift do they live at? z = 0 z = 0.2 z = 0.4 z = 0.6 Z =0.8

Explanation / Answer

Solving question 1

At any redshift ,temp is given by

T=To(1+z)

Whher To=2.725k

We have z=0.26

We got

T=3.43 K

Option(b) is correct

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