Fix massdef in miscentering calculations and virial delta_mdef

[hsinfan1996]

No description provided.

[coveralls]

coverage: 100.0%. remained the same
when pulling 8573b92 on issue/660/miscentering_massdef
into 047fed4 on main.

[combet]

Thank you @hsinfan1996 - this was super efficient :)

I confirm it behaves as expected for mean and critical now, but I just realised we still have a problem when mass_def=virial. In that case, I think Delta_vir is computed internally in the backend as a function of cosmology (i.e. it's not to the user to set a value for Delta).

However, when mis_from_backend=False, the code still uses user-defined self.delta_mdef which is not the right value for Delta_vir (unless the user computed it beforehand correctly).

So at the moment, having mis_from_backend=False and mass_def=virial does not behave as expected (mis_from_backend=True is alright of course, just much slower).

I see 2 options:

• simply prevent the combination mis_from_backend=False and mass_def=virial, with a printout explanation that mis_from_backend=False is only valid for mean and critical mass definition.
• implement a way to get Delta_vir from the backend and use that value when mass_def=virial.

Maybe option 1 is sufficient for the time being? What do you think @hsinfan1996?

[hsinfan1996]

I was thinking about virial massdef too. For the CCL backend, I can implement the function for getting Delta_vir right away. For NumCosmo, I think I know what function to use, but I will need some time to implement it. Hopefully, someone more familiar with NC can help me. So for now, I go for option 2.

[hsinfan1996]

@combet I added the functions that calculate Delta_vir to the supported backends (NC<=0.22 for now). However, since getting Delta_vir requires the redshift, which is different from other mass definitions, I am thinking what is the best way to set Delta_vir to the cluster or for it to be utilized by other functions. Any ideas? @m-aguena

[hsinfan1996]

To support virial massdef properly, all functions that call the relevant ones in generic.py have to get virial delta_mdef from the backends, so I added some functions to do the job.