21-cm brightness temperature monopole from CAMB
Posted: October 22 2020
Greetings!
I was wondering if it is possible to obtain the monopole of the brightness temperature (as a function of redshift) from CAMB. I am using the Python wrapper for CAMB.
My own attempt:
I have instructed CAMB to compute 21-cm relevant observables with:
pars.Do21cm = True
pars.transfer_21cm_cl = True
Switching these on returns different transfer functions when I then
run get_matter_transfer_data() and get transfer functions out, so it is doing something.
I have found that the 4th transfer function that the command returns
is the "21 cm monopole source". It is indexed by redshift and
wavenumber. However, I have doubts that this is the right place to
be looking as I would not expect a monopole signal to need
information about the primordial power spectrum. I suppose this
transfer function is supposed to be multiplied by the power spectrum and then
integrated/summed.
I was wondering if it is possible to obtain the monopole of the brightness temperature (as a function of redshift) from CAMB. I am using the Python wrapper for CAMB.
My own attempt:
I have instructed CAMB to compute 21-cm relevant observables with:
pars.Do21cm = True
pars.transfer_21cm_cl = True
Switching these on returns different transfer functions when I then
run get_matter_transfer_data() and get transfer functions out, so it is doing something.
I have found that the 4th transfer function that the command returns
is the "21 cm monopole source". It is indexed by redshift and
wavenumber. However, I have doubts that this is the right place to
be looking as I would not expect a monopole signal to need
information about the primordial power spectrum. I suppose this
transfer function is supposed to be multiplied by the power spectrum and then
integrated/summed.