pyccl.cells module

pyccl.cells.angular_cl(cosmo, tracer1, tracer2, ell, *, p_of_k_a='delta_matter:delta_matter', l_limber=-1, limber_max_error=0.01, limber_integration_method='qag_quad', non_limber_integration_method='FKEM', p_of_k_a_lin='delta_matter:delta_matter', return_meta=False)[source]

Calculate the angular (cross-)power spectrum for a pair of tracers.

Parameters:

  • cosmo (Cosmology) – A Cosmology object.

  • tracer1 (Tracer) – a Tracer object, of any kind.

  • tracer2 (Tracer) – a second Tracer object.

  • ell (float or array) – Angular multipole(s) at which to evaluate the angular power spectrum.

  • p_of_k_a (Pk2D, str or None) – 3D Power spectrum to project. If a string, it must correspond to one of the non-linear power spectra stored in cosmo (e.g. ‘delta_matter:delta_matter’).

  • l_limber (int, float or 'auto') – Angular wavenumber beyond which Limber’s approximation will be used. Defaults to -1. If ‘auto’, then the non-limber integrator will be used to compute the right transition point given the value of limber_max_error.

  • limber_max_error (float) – Maximum fractional error for Limber integration.

  • limber_integration_method (string) – integration method to be used for the Limber integrals. Possibilities: ‘qag_quad’ (GSL’s qag method backed up by quad when it fails) and ‘spline’ (the integrand is splined and then integrated numerically).

  • non_limber_integration_method (string) – integration method to be used for the non-Limber integrals. Currently the only method implemented is 'FKEM' (see the N5K paper for details).

  • p_of_k_a_lin (Pk2D, str or None) – 3D linear Power spectrum to project, for special use in PT calculations using the FKEM non-limber integration technique. If a string, it must correspond to one of the linear power spectra stored in cosmo (e.g. ‘delta_matter:delta_matter’).

  • return_meta (bool) – if True, also return a dictionary with various metadata about the calculation, such as l_limber as calculated by the non-limber integrator.

Returns:

Angular (cross-)power spectrum values, \(C_\ell\), for the pair of tracers, as a function of \(\ell\).

Return type:

float or array