popsynth.distributions.cosmological_distribution module

class popsynth.distributions.cosmological_distribution.CosmologicalDistribution(seed: int = 1234, name: str = 'cosmo', form: str = None, truth: Dict[str, Any] = {}, is_rate: bool = True)

Bases: popsynth.distribution.SpatialDistribution

__init__(seed: int = 1234, name: str = 'cosmo', form: str = None, truth: Dict[str, Any] = {}, is_rate: bool = True)

Base class for cosmological spatial distributions.

Parameters:

• seed (int) – Random seed
• name (str) – Name of the distribution
• form (str) – Mathematical description of distribution
• truth (dict[str, Any]) – True values of parameters
• is_rate (bool) – True if modelling a population of transient events, False if modelling a population of steady-state objects. Affects the time_adjustment method used in cosmo calculations. Default is True.

differential_volume(z)

Differential comoving volume in Gpc^3 sr^-1.

dV/dzdOmega

Parameters:z – Redshift Returns:The differential comoving volume in Gpc^-3 sr^-1.

time_adjustment(z)

Time adjustment factor to handle both transient and steady-state populations.

Parameters:z – Redshift Returns:Appropriate factor depending on is_rate

transform(L, z)

Transformation from luminosity to energy flux.

L / 4 pi dL^2

dL is in cm. Therefore for L in erg s^-1 returns flux in erg cm^-2 s^-1.

Parameters:

• L – Luminosity
• z – Redshift

Returns:

Flux

class popsynth.distributions.cosmological_distribution.SFRDistribution(seed: int = 1234, name: str = 'sfr', is_rate: bool = True)

Bases: popsynth.distributions.cosmological_distribution.CosmologicalDistribution

__init__(seed: int = 1234, name: str = 'sfr', is_rate: bool = True)

A star-formation like distribution of the form presented in Cole et al. 2001.

r0``(``a``+``rise``z)/(1 + (z/``peak)^``decay``)

Parameters:

• seed (int) – Random seed
• name (str) – Name of the distribution
• is_rate (bool) – True if modelling a population of transient events, False if modelling a population of steady-state objects. Affects the time_adjustment method used in cosmo calculations. Default is True.
• r0 (DistributionParameter) – The local density in units of Gpc^-3
• a (DistributionParameter) – Offset at z=0
• rise (DistributionParameter) – Rise at low z
• decay (DistributionParameter) – Decay at high z
• peak (DistributionParameter) – Peak of z distribution

a

dNdV(z)

The differential number of objects per volume element

Parameters:distance – Returns:

decay

peak

r0

rise

class popsynth.distributions.cosmological_distribution.ZPowerCosmoDistribution(seed: int = 1234, name: str = 'zpow_cosmo', is_rate: bool = True)

Bases: popsynth.distributions.cosmological_distribution.CosmologicalDistribution

Lambda

__init__(seed: int = 1234, name: str = 'zpow_cosmo', is_rate: bool = True)

A cosmological distribution where the density evolves as a power law.

Lambda (1+z)^``delta``

Parameters:

• seed (int) – Random seed
• name (str) – Name of the distribution
• is_rate (bool) – True if modelling a population of transient events, False if modelling a population of steady-state objects. Affects the time_adjustment method used in cosmo calculations. Default is True.
• Lambda (DistributionParameter) – The local density in units of Gpc^-3
• delta (DistributionParameter) – The index of the power law

dNdV(distance)

The differential number of objects per volume element

Parameters:distance – Returns:

delta