BUG: Overgeneration of galaxies

[Fox-Davidson]

Description

This fixes the overgeneration of galaxies caused by the lack of a $h_0^3$ factor in the number density calculation (required due to the units of $phi_*$. Attached are a PDF of a notebook showing this result and text files for the generation of the galaxies.
This will close #576 .

Checklist

• Follow the Contributor Guidelines
• Write unit tests
• Write documentation strings
• Assign someone from your working team to review this pull request
• Assign someone from the infrastructure team to review this pull request
  red_galaxy_text.txt
  blue_galaxy_text.txt
  Galaxy_Overgeneration_(Git).pdf

[philipp128]

I don't think this is the right place to account for h. The parameter phi_star has the same dimension [unit] as the luminosity function, which is 1/V/luminosity [commonly Mpc^-3 mag^-1]. That means phi_star must agree with these dimensions/units.

In your example, you are using the parameters of Tortorelli2020. In this work, they are giving phi_star in units of h_70 = H_0/70. So the input parameter must be corrected by this unit. However, as your defined cosmology includes H_0 = 70, h_70 is equal to 1. Therefore, the number that you have in your config files corresponds to units of Mpc^-3 mag^-1, which are as I said the physical units.

If we, however, want to enable phi_star to be given in units of h_0, we would also need to specify this in the documentation. But in this case, the parameter in your config file has the wrong value.

[philipp128]

The current implementation is correct but we will add clarification about the units in the docs with a new PR. Issue #576 will be changed accordingly.