Lensing emission angle¶
This module calculates the corrections to the standard lensed CMB power spectra results due to time delay and emission angle, following arXiv:1706.02673. This can be combined with the result from the postborn module to estimate the leading corrections to the standard lensing B modes.
Corrections to T and E are negligible, and not calculated. The result for BB includes approximately contributions from reionization, but this can optionally be turned off.

camb.emission_angle.
get_emission_angle_powers
(camb_background, PK, chi_source, lmax=3000, acc=1, lsamp=None)[source]¶ Get the power spectrum of \(\psi_d\), the potential for the emission angle, and its cross with standard lensing. Uses the Limber approximation (and assumes flat universe).
Parameters:  camb_background – a CAMB results object, used for calling background functions
 PK – a matter power spectrum interpolator (from camb.get_matter_power_interpolator)
 chi_source – comoving radial distance of source in Mpc
 lmax – maximum L
 acc – accuracy parameter
 lsamp – L sampling for the result
Returns: a InterpolatedUnivariateSpline object containing \(L(L+1) C_L\)

camb.emission_angle.
get_emission_delay_BB
(params, kmax=100, lmax=3000, non_linear=True, CMB_unit='muK', raw_cl=False, acc=1, lsamp=None, return_terms=False, include_reionization=True)[source]¶ Get B modes from emission angle and time delay effects. Uses fullsky result from appendix of arXiv:1706.02673
Parameters:  params –
model.CAMBparams
instance with cosmological parameters etc.  kmax – maximum k (in \({\rm Mpc}^{1}\) units)
 lmax – maximum \(\ell\)
 non_linear – include nonlinear corrections
 CMB_unit – normalization for the result
 raw_cl – if true return \(C_\ell\), else \(\ell(\ell+1)C_\ell/2\pi\)
 acc – accuracy setting, increase to test stability
 lsamp – array of \(\ell\) values to compute output at. If not set, set to sampling good for interpolation
 return_terms – return the three subterms separately rather than the total
 include_reionization – approximately include reionization terms by second scattering surface
Returns: InterpolatedUnivariateSpline for \(C_\ell^{BB}\)
 params –

camb.emission_angle.
get_source_cmb_cl
(params, CMB_unit='muK')[source]¶ Get the angular power spectrum of emission angle and time delay sources \(\psi_t\), \(\psi_\zeta\), as well as the perpendicular velocity and E polarization. All are returned with 1 and 2 versions, for recombination and reionization respectively. Note that this function destroys any custom sources currently configured.
Parameters:  params –
model.CAMBparams
instance with cosmological parameters etc.  CMB_unit – scale results from dimensionless, use ‘muK’ for \(\mu K^2\) units
Returns: dictionary of power spectra, with \(L(L+1)/2\pi\) factors.
 params –