FlatUniverseCosmology Class Reference

#include <FlatUniverseCosmology.hpp>

Inheritance diagram for FlatUniverseCosmology:

Public Member Functions
double	angularDiameterDistance () const override
double	luminosityDistance () const override
double	matterDensityFraction () const
double	modelRedshift () const override
double	redshift () const
double	reducedHubbleConstant () const
double	relativeExpansionRate () const override
virtual double	angularDiameterDistance () const =0
virtual double	luminosityDistance () const =0
virtual double	modelRedshift () const =0
virtual double	relativeExpansionRate () const =0
Public Member Functions inherited from SimulationItem
template<class T >
T *	find (bool setup=true) const
template<class T >
T *	interface (int levels=-999999, bool setup=true) const
virtual string	itemName () const
void	setup ()
string	typeAndName () const
Public Member Functions inherited from Item
	Item (const Item &)=delete
virtual	~Item ()
void	addChild (Item *child)
const vector< Item * > &	children () const
virtual void	clearItemListProperty (const PropertyDef *property)
void	destroyChild (Item *child)
virtual bool	getBoolProperty (const PropertyDef *property) const
virtual vector< double >	getDoubleListProperty (const PropertyDef *property) const
virtual double	getDoubleProperty (const PropertyDef *property) const
virtual string	getEnumProperty (const PropertyDef *property) const
virtual int	getIntProperty (const PropertyDef *property) const
virtual vector< Item * >	getItemListProperty (const PropertyDef *property) const
virtual Item *	getItemProperty (const PropertyDef *property) const
virtual string	getStringProperty (const PropertyDef *property) const
int	getUtilityProperty (string name) const
virtual void	insertIntoItemListProperty (const PropertyDef *property, int index, Item *item)
Item &	operator= (const Item &)=delete
Item *	parent () const
virtual void	removeFromItemListProperty (const PropertyDef *property, int index)
virtual void	setBoolProperty (const PropertyDef *property, bool value)
virtual void	setDoubleListProperty (const PropertyDef *property, vector< double > value)
virtual void	setDoubleProperty (const PropertyDef *property, double value)
virtual void	setEnumProperty (const PropertyDef *property, string value)
virtual void	setIntProperty (const PropertyDef *property, int value)
virtual void	setItemProperty (const PropertyDef *property, Item *item)
virtual void	setStringProperty (const PropertyDef *property, string value)
void	setUtilityProperty (string name, int value)
virtual string	type () const

Protected Member Functions
	FlatUniverseCosmology ()
Protected Member Functions inherited from Cosmology
	Cosmology ()
Protected Member Functions inherited from SimulationItem
	SimulationItem ()
virtual bool	offersInterface (const std::type_info &interfaceTypeInfo) const
virtual void	setupSelfAfter ()
virtual void	setupSelfBefore ()
Protected Member Functions inherited from Item
	Item ()

Private Types
using	BaseType = Cosmology
using	ItemType = FlatUniverseCosmology

Private Attributes
double	_matterDensityFraction
double	_redshift
double	_reducedHubbleConstant

Friends
class	ItemRegistry

Detailed Description

An instance of the FlatUniverseCosmology class represents a cosmology where the simulated model resides at a given redshift $z$ in a standard spatially-flat $\mathrm{\Lambda }\mathrm{C}\mathrm{D}\mathrm{M}$ universe. The allowed redshift range is $0\le z\le 15$, i.e. including the epoch of reionization. If $z=0$, the behavior is the same as that of a LocalUniverseCosmology.

In addition to the redshift, this cosmology has two parameters, namely the reduced Hubble constant $h=H_0/(100\mathrm{k}\mathrm{m}{\mathrm{s}}^{-1}{\mathrm{M}\mathrm{p}\mathrm{c}}^{-1})$ and the matter density fraction ${\mathrm{\Omega }}_{\mathrm{m}}$. The default values for these parameters are compatible with the latest observations and close to the values used by many recent cosmological simulations.

For a spatially-flat cosmology, the line-of-sight and transverse comoving distances are identical. We further ignore the radiation density, which is justified for the allowed redshift range $z\le 15$. With these assumptions, the comoving distance $d_{\mathrm{M}}(z)$ corresponding to redshift $z$ can be obtained from the matter density fraction ${\mathrm{\Omega }}_{\mathrm{m}}$ and the Hubble constant $H_0=h\times 100\mathrm{k}\mathrm{m}{\mathrm{s}}^{-1}{\mathrm{M}\mathrm{p}\mathrm{c}}^{-1}$ using

$$d_{\mathrm{M}}(z)=\frac{c}{H_0}{\int }_0^z\frac{\mathrm{d}{z}^{\prime }}{\sqrt{{\mathrm{\Omega }}_{\mathrm{m}}(1+z^{\prime }{)}^3+(1-{\mathrm{\Omega }}_{\mathrm{m}})}}$$

where $c$ is the speed of light.

The angular-diameter distance $d_{\mathrm{A}}(z)$ and the luminosity distance $d_{\mathrm{L}}(z)$ are then obtained from

$$d_{\mathrm{A}}(z)=(1+z{)}^{-1}{d}_{\mathrm{M}}(z)$$

and

$$d_{\mathrm{L}}(z)=(1+z)d_{\mathrm{M}}(z).$$

Finally, the relative expansion rate of the universe $H=\dot{a}/a$, usually called the Hubble parameter, is given by

$$H(z)=H_0\sqrt{{\mathrm{\Omega }}_{\mathrm{m}}(1+z^{\prime }{)}^3+(1-{\mathrm{\Omega }}_{\mathrm{m}})}.$$

Constructor & Destructor Documentation

FlatUniverseCosmology()

FlatUniverseCosmology::FlatUniverseCosmology ( )

inlineprotected

Default constructor for concrete Item subclass FlatUniverseCosmology : "the model is at a given redshift in a flat universe" .

When a value is entered for this property, the names provided by the conditional value expression "redshift:NonZeroRedshift" are inserted into the name sets used for evaluating Boolean expressions.

Member Function Documentation

angularDiameterDistance()

double FlatUniverseCosmology::angularDiameterDistance ( ) const

overridevirtual

This function returns the angular-diameter distance $d_{\mathrm{A}}(z)$, calculated from the user-configured cosmology parameters as described in the class header. The integral is evaluated numerically. We don't worry about performance because this function is called just once during simulation setup.

Implements Cosmology.

luminosityDistance()

double FlatUniverseCosmology::luminosityDistance ( ) const

overridevirtual

This function returns the luminosity distance. For this class, calculated from the user-configured cosmology parameters as described in the class header. The integral is evaluated numerically. We don't worry about performance because this function is called just once during simulation setup.

Implements Cosmology.

matterDensityFraction()

FlatUniverseCosmology::matterDensityFraction ( ) const

inline

This function returns the value of the discoverable double property matterDensityFraction : "the cosmological matter density fraction Ω_m" .

The minimum value for this property is "0.1" .

The maximum value for this property is "0.9" .

The default value for this property is given by the conditional value expression "0.310" .

This property is relevant only if the Boolean expression "redshift" evaluates to true after replacing the names by true or false depending on their presence.

modelRedshift()

double FlatUniverseCosmology::modelRedshift ( ) const

overridevirtual

This function returns the redshift at which the model resides.

Implements Cosmology.

redshift()

FlatUniverseCosmology::redshift ( ) const

inline

This function returns the value of the discoverable double property redshift : "the redshift z of the model coordinate frame" .

The minimum value for this property is "[0" .

The maximum value for this property is "15]" .

The default value for this property is given by the conditional value expression "1" .

reducedHubbleConstant()

FlatUniverseCosmology::reducedHubbleConstant ( ) const

inline

This function returns the value of the discoverable double property reducedHubbleConstant : "the reduced Hubble constant h" .

The minimum value for this property is "0.3" .

The maximum value for this property is "1" .

The default value for this property is given by the conditional value expression "0.675" .

This property is relevant only if the Boolean expression "redshift" evaluates to true after replacing the names by true or false depending on their presence.

relativeExpansionRate()

double FlatUniverseCosmology::relativeExpansionRate ( ) const

overridevirtual

This function returns the relative expansion rate of the universe, $H=\dot{a}/a$, often called the Hubble parameter. The function returns the value in SI units, i.e. ${\mathrm{s}}^{-1}$.

Implements Cosmology.

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The documentation for this class was generated from the following file:

• FlatUniverseCosmology.hpp