dsf.data_vector.ccl_integration module

Excess surface density projection from CCL power spectra.

This module provides the standalone DeltaSigma class for calculating excess surface density profiles from CCL Pk2D objects.

The calculation uses a second-order projected Hankel transform,

\[\Delta\Sigma(R, a) = \int_0^\infty \frac{k\,\mathrm{d}k}{2\pi} \tilde{\rho}(k, a) J_2(kR),\]

where the input Pk2D supplies the Fourier-space density profile. The transform is evaluated using DSF’s FFTLog implementation.

class dsf.data_vector.ccl_integration.DeltaSigma(*, pk2d, k=None)[source]

Bases: object

Calculate excess surface density from a CCL Pk2D object.

The class evaluates the Fourier-space profile on a logarithmic wavenumber grid and applies a second-order Hankel transform to obtain \(\Delta\Sigma(R, a)\).

The input Pk2D must include the required density normalization. Projected radii are comoving and expressed in Mpc.

Parameters:

  • pk2d (ccl.Pk2D)

  • k (NDArray[np.float64] | None)

delta_sigma(cosmo, r, a)[source]

Calculate \(\Delta\Sigma(R, a)\) at projected radii.

Parameters:

  • cosmo (Cosmology) – CCL cosmology object.

  • r (NDArray[float64]) – Projected comoving radii in Mpc.

  • a (float) – Scale factor at which the profile is evaluated.

Returns:

Excess surface density in the projected-density units implied by the input Pk2D.

Return type:

NDArray[float64]