- #1
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I am trying to understand this graph but I am confused about the distance definitions. So there's an object located at a comoving distance ##r##.
The proper distance of the object at ##z'## can be written as
$$d(z{'}) = \frac{1}{1+z{'}}\int_0^{z{'}} \frac{dz{'}}{H(z{'})}$$
In this case,
$$d_1(z) = \frac{1}{1+z}\int_0^z \frac{dz}{H(z)}$$
and
$$d_0(z) = \int_0^z \frac{dz}{H(z)}$$
And we can also define the conformal time where it represents the distance taken by photon from the distant galaxy to us and can be written as
$$\eta(z) = \int_0^z \frac{dz}{H(z)}$$
There is also lookback time/distance but I am not sure it's same as the conformal time or not...
Are these definition that I have made are correct ?