# HaloMassInterpolQuenching¶

class halotools.empirical_models.HaloMassInterpolQuenching(halo_mass_key, halo_mass_abscissa, quiescent_fraction_control_values, **kwargs)[source] [edit on github]

Model for the quiescent fraction as a function of halo mass defined by interpolating between a set of input control points.

BinaryGalpropInterpolModel
Parent class from which all behavior derives.

Notes

The interpolation is automatically done in log-space.

Parameters: halo_mass_key : string Name of the column of the halo table storing the mass-like variable the model is based on, e.g., ‘halo_mvir’ or ‘halo_m200b’. halo_mass_abscissa : array_like Values of halo mass at which the quiescent fraction is specified. quiescent_fraction_control_values : array_like Values of the quiescent fraction evaluated at the halo_mass_abscissa. gal_type : string, optional Name of the galaxy population. This is only relevant if you are building an HOD-style composite model.

Examples

Suppose you wish to build a model for quenching in which 1/4 of galaxies in Milky Way halos are quiescent and 9/10 of galaxies in cluster halos are quiescent:

>>> model_instance = HaloMassInterpolQuenching('halo_mvir', [1e12, 1e15], [0.25, 0.9])


Your model has a method called mean_quiescent_fraction that accepts a prim_haloprop keyword argument:

>>> mass_array = np.logspace(10, 15, 1000)
>>> quiescent_fraction = model_instance.mean_quiescent_fraction(prim_haloprop = mass_array)


You can also generate Monte Carlo realizations of quiescent designation:

>>> quiescent_designation = model_instance.mc_quiescent(prim_haloprop = mass_array)


Now quiescent_designation is a boolean-valued array of the same length as the input mass_array. True values correspond to quiescent galaxies, and conversely.

At any time, you can change the values of the quiescent fraction in your model by changing the appropriate key in param_dict:

>>> model_instance.param_dict['quiescent_ordinates_param1'] = 0.35


The above line of code changed the quiescent fraction to 0.35 at the first control value of $$M_{\rm vir} = 10^{12}M_{\odot}$$. You will have one parameter for every control value you used to instantiate the model. While you can always change the quiescent fraction of your model instance at any given control value, you cannot change the halo masses at which the control values are evaluated. To do that, you must instantiate a new model.

If you passed in a gal_type keyword, the keys of your param_dict will reflect this choice:

>>> model_instance = HaloMassInterpolQuenching('halo_mvir', [1e12, 1e15], [0.25, 0.9], gal_type = 'centrals')
>>> model_instance.param_dict['centrals_quiescent_ordinates_param1'] = 0.35


The purpose for this distinction is to provide disambiguation for composite models that use the HaloMassInterpolQuenching class for more than one galaxy population.