astropy:docs

Navigation

Kravtsov04Cens

class halotools.hod_components.Kravtsov04Cens(parameter_dict=None, threshold=-20, gal_type='centrals')[source] [edit on github]

Bases: object

Erf function model for the occupation statistics of central galaxies, introduced in Kravtsov et al. 2004, arXiv:0308519.

Parameters:

parameter_dict : dictionary, optional.

Contains values for the parameters specifying the model. Dictionary keys are ‘logMmin_cen’ and ‘sigma_logM’

Their best-fit parameter values provided in Table 1 of Zheng et al. (2007) are pre-loaded into this class, and can be accessed via the published_parameters method.

threshold : float, optional.

Luminosity threshold of the mock galaxy sample. If specified, input value must agree with one of the thresholds used in Zheng07 to fit HODs: [-18, -18.5, -19, -19.5, -20, -20.5, -21, -21.5, -22]. Default value is specified in the defaults module.

gal_type : string, optional

Sets the key value used by hod_designer and hod_factory to access the behavior of the methods of this class.

Methods Summary

mc_occupation(logM) Method to generate Monte Carlo realizations of the abundance of galaxies.
mean_occupation(logM) Expected number of central galaxies in a halo of mass logM.
published_parameters(threshold) Best-fit HOD parameters from Table 1 of Zheng et al.

Methods Documentation

mc_occupation(logM)[source] [edit on github]

Method to generate Monte Carlo realizations of the abundance of galaxies.

Parameters:

logM : array

array of log_{10}(M) of halos in catalog
Returns:

mc_abundance : array

array of length len(logM) giving the number of self.gal_type galaxies in the halos.
mean_occupation(logM)[source] [edit on github]

Expected number of central galaxies in a halo of mass logM. See Equation 2 of arXiv:0703457.

Parameters:

logM : array

array of log_{10}(M) of halos in catalog
Returns:

mean_ncen : array

Notes

Mean number of central galaxies in a host halo of the specified mass.

\langle N_{cen} \rangle_{M} = \frac{1}{2}\left( 1 + erf\left( \frac{log_{10}M - log_{10}M_{min}}{\sigma_{log_{10}M}} \right) \right)

published_parameters(threshold)[source] [edit on github]

Best-fit HOD parameters from Table 1 of Zheng et al. 2007.

Parameters:

threshold : float

Luminosity threshold defining the SDSS sample to which Zheng et al. fit their HOD model. Must be agree with one of the published values: [-18, -18.5, -19, -19.5, -20, -20.5, -21, -21.5, -22].
Returns:

parameter_dict : dict

Dictionary of model parameters whose values have been set to agree with the values taken from Table 1 of Zheng et al. 2007.

Page Contents