galsbi.ucat.galaxy_population_models package

Submodules

galsbi.ucat.galaxy_population_models.galaxy_light_profile module

Created 2021 author: Tomasz Kacprzak

galsbi.ucat.galaxy_population_models.galaxy_light_profile.sample_sersic_berge(numgalaxies, int_mag, par)

Sample the Sersic index-distribution parametrized as described in (Berge et al. 2013)

Parameters:

• numgalaxies – number of galaxies, i.e. number of samples

• int_mag – intrinsic, unmagnified magnitude of all galaxies

• par – ctx.parameters; part of ctx containing parameters

Returns:

Sersic index

galsbi.ucat.galaxy_population_models.galaxy_light_profile.sample_sersic_betaprime(n_gal, mode, size, alpha=0, z=0.0, min_n=0.2, max_n=5.0)

Sample the Sersic index-distribution parametrized as described in (Moser et al. 2024). The parameter mode corresponds to the mode of the distribution, the size parameter is responsible for the scatter (with larger size the distribution becomes tighter). The alpha parameter is responsible for the redshift dependence of the mode. This was first introduced in Fischbacher et al. 2024.

Parameters:

• n_gal – number of galaxies, i.e. number of samples

• mode – mode of the distribution

• size – size of the distribution (with larger size the distribution becomes tighter)

• alpha – redshift dependence of the mode

• z – redshift

• min_n – minimum Sersic index, raise exception if the sampled value is below this value

• max_n – maximum Sersic index, raise exception if the sampled value is above this value

Returns:

Sersic index

galsbi.ucat.galaxy_population_models.galaxy_light_profile.sample_sersic_for_galaxy_type(n_gal, galaxy_type, app_mag, par, z=0.0)

galsbi.ucat.galaxy_population_models.galaxy_luminosity_function module

Created on Sept 2021 author: Tomasz Kacprzak using code from: Joerg Herbel

class galsbi.ucat.galaxy_population_models.galaxy_luminosity_function.LuminosityFunction(name, lum_fct_parametrization, m_star_slope, m_star_intcpt, phi_star_amp, phi_star_exp, z_const, alpha, cosmo, pixarea, galaxy_type, seed_ngal, z_res=0.001, m_res=0.001, z_max=inf, m_max=2, z_m_intp=None, ngal_multiplier=1)

Bases: object

Luminosity function

sample_z_mabs_and_apply_cut(seed_ngal, seed_lumfun, n_gal_max=inf, size_chunk=10000)

This function gets the abs mag and z using chunking, which uses less memory than the original method. It does not give exactly the same result as before due to different order of random draws in z_mabs_sampler, but it’s the same sample.

class galsbi.ucat.galaxy_population_models.galaxy_luminosity_function.NumGalCalculator(z_max, m_max, parametrization, z_const, alpha, m_star_par, phi_star_par, cosmo, pixarea, ngal_multiplier=1)

Bases: object

Computes galaxy number counts by integrating the galaxy luminosity function. The integral over absolute magnitudes can be done analytically, while the integral over redshifts is computed numerically. See also docs/jupyter_notebooks/sample_redshift_magnitude.ipynb.

class galsbi.ucat.galaxy_population_models.galaxy_luminosity_function.RedshiftAbsMagSampler(z_res, z_max, m_res, m_max, parametrization, z_const, alpha, m_star_par, phi_star_par, cosmo)

Bases: object

Samples redshifts and absolute magnitudes from the galaxy luminosity function. The sampling is done by first drawing redshifts from the redshift-pdf obtained by integrating out absolute magnitudes. Then, we sample absolute magnitudes from the conditional pdfs obtained by conditioning the luminosity function on the sampled redshifts (the conditional pdf is different for each redshift). See also docs/jupyter_notebooks/sample_redshift_magnitude.ipynb and docs/jupyter_notebooks/test_self_consistency.ipynb.

galsbi.ucat.galaxy_population_models.galaxy_luminosity_function.find_closest_ind(grid, vals)

galsbi.ucat.galaxy_population_models.galaxy_luminosity_function.initialize_luminosity_functions(par, pixarea, cosmo, z_m_intp=None)

galsbi.ucat.galaxy_population_models.galaxy_luminosity_function.m_star_lum_fct(z, parametrization, z_const, slope, intercept)

galsbi.ucat.galaxy_population_models.galaxy_luminosity_function.maximum_redshift(z_m_intp, m_max, z_max, parametrization, z_const, alpha, m_star_par, seed_ngal)

Computes the maximum redshift up to which we sample objects from the luminosity function. The cutoff is based on the criterion that the CDF for absolute magnitudes is larger than 1e-5, i.e. that there is a reasonable probability of actually obtaining objects at this redshift and absolute magnitude which still pass the cut on par.gals_mag_max.

galsbi.ucat.galaxy_population_models.galaxy_luminosity_function.phi_star_lum_fct(z, parametrization, amplitude, exp)

galsbi.ucat.galaxy_population_models.galaxy_luminosity_function.upper_inc_gamma(a, x)

galsbi.ucat.galaxy_population_models.galaxy_position module

Created 2021 author: Tomasz Kacprzak

galsbi.ucat.galaxy_population_models.galaxy_position.sample_position_uniform(numobj, w, pixel_index, nside)

Sample a Healpix pixel uniformly

Parameters:

• numobj – Number of uniform samples

• w – wcs-object containing all the relevant wcs-information

• pixel_index – Index of the Healpix pixels sampled

• nside – NSIDE of the Healpix map

Returns:

Uniformly drawn x-coordinate (in pixels)

Returns:

Uniformly drawn y-coordinate (in pixels)

galsbi.ucat.galaxy_population_models.galaxy_sed module

Created 2021 author: Tomasz Kacprzak

galsbi.ucat.galaxy_population_models.galaxy_sed.dirichlet_alpha_ev(z, alpha0, alpha1, z1)

galsbi.ucat.galaxy_population_models.galaxy_sed.draw_dirichlet_add_weight(alpha, weight)

galsbi.ucat.galaxy_population_models.galaxy_sed.sample_template_coeff_dirichlet(z, alpha0, alpha1, z1, weight)

Samples template coefficients from redshift-dependent Dirichlet distributions. See also docs/jupyter_notebooks/coeff_distribution_dirichlet.ipynb.

galsbi.ucat.galaxy_population_models.galaxy_sed.sample_template_coeff_dirichlet__alpha_mode(z, amode0, amode1, z1, weight, alpha0_std, alpha1_std)

Samples template coefficients from redshift-dependent Dirichlet distributions. See also docs/jupyter_notebooks/coeff_distribution_dirichlet.ipynb. Then the alpha0 and alpha1 will be scaled such that std(alpha)=alpha_std, for a equal alphas. alpha_std is also interpolated between redshifts.

galsbi.ucat.galaxy_population_models.galaxy_sed.sample_template_coeff_lumfuncs(par, redshift_z, n_templates)

galsbi.ucat.galaxy_population_models.galaxy_shape module

Created 2021 author: Tomasz Kacprzak

galsbi.ucat.galaxy_population_models.galaxy_shape.backwards_compatibility(par)

galsbi.ucat.galaxy_population_models.galaxy_shape.distortion_to_shear(distortion_x)

galsbi.ucat.galaxy_population_models.galaxy_shape.pe_bulge(ngal, b=2.368, c=6.691)

From miller2013.

galsbi.ucat.galaxy_population_models.galaxy_shape.pe_disc(ngal, log_a=np.float64(-1.3708147902715042), emax=0.8, emin=0.0256, pow_alpha=1)

From miller2013.

galsbi.ucat.galaxy_population_models.galaxy_shape.sample_ellipticities_beta(n_gal, par)

galsbi.ucat.galaxy_population_models.galaxy_shape.sample_ellipticities_beta_mode(n_gal, ell_beta_ab_sum, ell_beta_mode, ell_beta_emax)

galsbi.ucat.galaxy_population_models.galaxy_shape.sample_ellipticities_for_galaxy_type(n_gal, galaxy_type, par)

galsbi.ucat.galaxy_population_models.galaxy_shape.sample_ellipticities_gaussian(numgalaxies, e1_mean, e2_mean, e1_sigma, e2_sigma)

Sample Gaussian distributions for the intrinsic e1 and e2 while enforcing that e1**2 + e2**2 <= 1

Parameters:

• numgalaxies – number of galaxies, i.e. number of samples

• par – ctx.parameters; part of ctx containing parameters

Returns:

e1 values

Returns:

e2 values

galsbi.ucat.galaxy_population_models.galaxy_size module

Created 2021 author: Tomasz Kacprzak

galsbi.ucat.galaxy_population_models.galaxy_size.apply_pycosmo_distfun(dist_fun, z)

galsbi.ucat.galaxy_population_models.galaxy_size.backwards_compatibility(par)

galsbi.ucat.galaxy_population_models.galaxy_size.r50_phys_to_ang(r50_phys, cosmo, z)

Convert physical size to angular size

Parameters:

• r50_phys – physical size of the galaxy in kpc

• cosmo – cosmological model

• z – redshift of the galaxy

Returns:

angular size of the galaxy in arcsec

galsbi.ucat.galaxy_population_models.galaxy_size.sample_r50_for_galaxy_type(z, abs_mag, cosmo, par, galaxy_type)

Sample the physical size of a galaxy given its absolute magnitude and redshift. The physical size is sampled from a log-normal distribution with a mean that depends on the absolute magnitude and redshift. The physical size is then converted to an angular size using the cosmological distance.

Parameters:

• z – redshift of the galaxy

• abs_mag – absolute magnitude of the galaxy

• cosmo – cosmological model

• par – ucat parameters

• galaxy_type – type of the galaxy (e.g. “red”, “blue”)

Returns:

angular size of the galaxy in pixels, in arcsec and physical size in kpc

galsbi.ucat.galaxy_population_models.galaxy_size.sample_r50_phys(abs_mag_shift, logr50_phys_std, logr50_phys_mean_slope, logr50_phys_mean_intcpt, logr50_alpha=0.0, z=0.0)

Module contents