dsf.data_vector.mag_bias module

Lens-magnification correction for Delta Sigma calculations.

This module computes the correction to the comoving excess surface density profile caused by magnification of the lens sample. The correction is evaluated using a nested integral over foreground redshift and multipole.

The public function delta_sigma_lens_mag_correction returns the quantity that should be subtracted from the observed Delta Sigma signal when including lens magnification.

The calculation currently approximates the source redshift as

z_source = z_lens + delta_z_source,

where delta_z_source is controlled by the lens-magnification integration parameters.

dsf.data_vector.mag_bias.delta_sigma_lens_mag_correction(r, a, cosmo, alpha_lens)[source]

Compute the lens-magnification correction to Delta Sigma.

This returns the comoving correction to the excess surface density profile caused by magnification of the lens sample. The correction is evaluated at lens scale factor a and projected comoving radii r.

The returned correction has the same radial shape as r and is intended to be subtracted from the measured Delta Sigma signal.

The source redshift is approximated as

\[z_\mathrm{s} = z_\mathrm{l} + \Delta z_\mathrm{s},\]

where delta_z_source is taken from the lens-magnification integration parameters.

Parameters:

  • r (ndarray[tuple[Any, ...], dtype[float64]]) – Comoving projected radii in Mpc.

  • a (float) – Lens scale factor.

  • cosmo (Cosmology) – CCL cosmology object.

  • alpha_lens (float) – Lens-sample magnification-bias slope. The correction is proportional to alpha_lens - 1.

Returns:

Comoving lens-magnification correction in \(M_\odot / \mathrm{pc}^2\).

Raises:

ValueError – If the radius array, scale factor, lens magnification-bias slope, or derived lens/source redshift pair is invalid.

Return type:

ndarray[tuple[Any, …], dtype[float64]]

dsf.data_vector.mag_bias.get_lens_mag_integ_params()[source]

Return the lens-magnification integration parameters.

Returns:

Copy of the current lens-magnification integration parameter dictionary.

Return type:

dict[str, int | float]

dsf.data_vector.mag_bias.set_lens_mag_integ_params(**kwargs)[source]

Update the lens-magnification integration parameters.

Parameters:

**kwargs (Any) – Integration parameters to update. Supported keys are n_ell, ell_min, ell_max, z_stepsize, z_min, and delta_z_source.

Raises:

  • KeyError – If an unknown integration parameter is supplied.

  • ValueError – If the updated integration parameters are invalid.

Return type:

None