xlens.simulator.perturbation

Lensing and astrometric perturbation models for simulated galaxies.

Submodules

Classes

`DcrDistort`	Apply an astrometric position shift to simulate DCR effects.
`ShearHalo`	Shear and convergence field generated by an NFW halo lens.
`ShearLogNormalFlat`	Flat-sky log-normal shear field generated from a CCL weak-lensing
`ShearRedshift`	Constant shear in each redshift slice.

Package Contents

class DcrDistort(distort_func)[source]

Bases: object

Apply an astrometric position shift to simulate DCR effects.

distort_func

distort_galaxy(gso, shift, redshift)[source]

This function distorts the galaxy’s shape and position :param gso (galsim object): :type gso (galsim object): galsim galaxy :param shift (galsim.PositionD): :type shift (galsim.PositionD): position of the galaxy :param redshift (float): :type redshift (float): redshift of galaxy

Returns:: distorted galaxy object and shift
Return type:: gso, shift

class ShearHalo(*, mass, conc, z_lens, halo_profile='NFW', cosmo=None, no_kappa=False, gmax=0.95)[source]

Bases: object

Shear and convergence field generated by an NFW halo lens.

cosmo = None

mass

z_lens

conc

no_kappa = False

lens

lens_solver

gmax = 0.95

distort_galaxy(src)[source]

This function distorts the galaxy’s shape and position :param src (np.array): :type src (np.array): row of structured array

Return type:: distorted galaxy position and lensing distortions

class ShearLogNormalFlat(z_source, field_size_deg=5.0, npix=2048, seed=None)[source]

Flat-sky log-normal shear field generated from a CCL weak-lensing power spectrum.

The constructor computes kappa, gamma1, and gamma2 maps and builds bivariate spline interpolators so that distort_galaxy can evaluate the lensing fields at arbitrary sky positions.

Parameters:

z_source (float) – Source redshift for the weak-lensing tracer.
field_size_deg (float, optional) – Side length of the square field in degrees.
npix (int, optional) – Number of pixels per side used for the Fourier-space generation.
seed (int or None, optional) – Random seed for reproducible field realisations.

cosmo

z_source

field_size_deg = 5.0

npix = 2048

seed = None

ell

cl_kappa

kappa_G_map

kappa_LN_map

gamma1_map

gamma2_map

kappa_map

kappa_interp

gamma1_interp

gamma2_interp

distort_galaxy(src)[source]

Return lensing distortions interpolated at the galaxy position.

Parameters:: src (numpy structured scalar) – Row with "dx" and "dy" fields (arcseconds).
Returns:: Standard shear result dict (see _get_shear_res_dict()).
Return type:: dict

class ShearRedshift(z_bounds, mode, g_dist='g1', shear_value=0.02, kappa_value=0.0)[source]

Bases: object

Constant shear in each redshift slice.

The shear pattern across redshift bins is encoded as a ternary integer (mode), where each base-3 digit maps to -shear_value, +shear_value, or 0.0.

Parameters:

z_bounds (list[float]) – Redshift bin boundaries (length nz_bins + 1).
mode (int) – Ternary-encoded shear assignment (see class docstring).
g_dist ({'g1', 'g2'}) – Which shear component receives the test signal.
shear_value (float) – Absolute shear amplitude per bin.
kappa_value (float) – Constant convergence applied to all bins.

nz_bins

code

z_bounds

g_dist = 'g1'

shear_value = 0.02

shear_list

kappa = 0.0

determine_shear_list(code)[source]: Convert a ternary code string into a list of shear values.

_get_zshear(redshift)[source]: Return the shear value for a galaxy at the given redshift.

get_shear(redshift)[source]: Return (g1, g2, mu, gamma1, gamma2) for a given redshift.

distort_galaxy(src)[source]

This function distorts the galaxy’s shape and position :param src (np.array): :type src (np.array): row of structured array

Return type:: distorted galaxy position and lensing distortions