MultiGrainDustMix Class Reference

#include <MultiGrainDustMix.hpp>

Inheritance diagram for MultiGrainDustMix:

Public Member Functions
Array	emissivity (const Array &Jv) const override
bool	hasStochasticDustEmission () const override
int	numPopulations () const override
const GrainPopulation *	population (int c) const
double	populationBulkDensity (int c) const override
string	populationGrainType (int c) const override
double	populationMass (int c) const override
double	populationNormalization (int c) const
const GrainSizeDistribution *	populationSizeDistribution (int c) const override
Range	populationSizeRange (int c) const override
double	totalMass () const override
Public Member Functions inherited from DustMix
double	asymmpar (double lambda) const override
Array	emissionSpectrum (const MaterialState *state, const Array &Jv) const override
DisjointWavelengthGrid *	emissionWavelengthGrid () const override
Array	emissivity (const Array &Jv) const override
bool	hasContinuumEmission () const override
double	indicativeTemperature (const MaterialState *state, const Array &Jv) const override
double	mass () const override
MaterialType	materialType () const override
double	opacityAbs (double lambda, const MaterialState *state, const PhotonPacket *pp) const override
double	opacityExt (double lambda, const MaterialState *state, const PhotonPacket *pp) const override
double	opacitySca (double lambda, const MaterialState *state, const PhotonPacket *pp) const override
void	peeloffScattering (double &I, double &Q, double &U, double &V, double &lambda, Direction bfkobs, Direction bfky, const MaterialState *state, const PhotonPacket *pp) const override
void	performScattering (double lambda, const MaterialState *state, PhotonPacket *pp) const override
virtual ScatteringMode	scatteringMode () const
double	sectionAbs (double lambda) const override
double	sectionExt (double lambda) const override
const Array &	sectionsAbs (double lambda) const override
const Array &	sectionsAbspol (double lambda) const override
double	sectionSca (double lambda) const override
vector< StateVariable >	specificStateVariableInfo () const override
const Array &	thetaGrid () const override
Public Member Functions inherited from MaterialMix
virtual double	asymmpar (double lambda) const
virtual Array	emissionSpectrum (const MaterialState *state, const Array &Jv) const
virtual DisjointWavelengthGrid *	emissionWavelengthGrid () const
virtual Array	emissivity (const Array &Jv) const
virtual bool	hasContinuumEmission () const
virtual DynamicStateType	hasDynamicMediumState () const
virtual bool	hasExtraSpecificState () const
virtual bool	hasLineEmission () const
virtual bool	hasNegativeExtinction () const
virtual bool	hasPolarizedAbsorption () const
virtual bool	hasPolarizedEmission () const
virtual bool	hasPolarizedScattering () const
virtual bool	hasResonantScattering () const
virtual bool	hasScatteringDispersion () const
virtual bool	hasStochasticDustEmission () const
virtual double	indicativeTemperature (const MaterialState *state, const Array &Jv) const
virtual void	initializeSpecificState (MaterialState *state, double metallicity, double temperature, const Array &params) const
bool	isDust () const
bool	isElectrons () const
bool	isGas () const
virtual bool	isSpecificStateConverged (int numCells, int numUpdated, int numNotConverged, MaterialState *currentAggregate, MaterialState *previousAggregate) const
virtual Array	lineEmissionCenters () const
virtual Array	lineEmissionMasses () const
virtual Array	lineEmissionSpectrum (const MaterialState *state, const Array &Jv) const
virtual double	mass () const =0
virtual MaterialType	materialType () const =0
virtual double	opacityAbs (double lambda, const MaterialState *state, const PhotonPacket *pp) const =0
virtual double	opacityExt (double lambda, const MaterialState *state, const PhotonPacket *pp) const =0
virtual double	opacitySca (double lambda, const MaterialState *state, const PhotonPacket *pp) const =0
virtual vector< SnapshotParameter >	parameterInfo () const
virtual void	peeloffScattering (double &I, double &Q, double &U, double &V, double &lambda, Direction bfkobs, Direction bfky, const MaterialState *state, const PhotonPacket *pp) const =0
virtual void	performScattering (double lambda, const MaterialState *state, PhotonPacket *pp) const =0
virtual double	sectionAbs (double lambda) const =0
virtual double	sectionExt (double lambda) const =0
virtual const Array &	sectionsAbs (double lambda) const
virtual const Array &	sectionsAbspol (double lambda) const
virtual double	sectionSca (double lambda) const =0
virtual vector< StateVariable >	specificStateVariableInfo () const =0
virtual const Array &	thetaGrid () const
virtual UpdateStatus	updateSpecificState (MaterialState *state, const Array &Jv) const
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
Public Member Functions inherited from MultiGrainPopulationInterface
virtual	~MultiGrainPopulationInterface ()
virtual int	numPopulations () const =0
virtual double	populationBulkDensity (int c) const =0
virtual string	populationGrainType (int c) const =0
virtual double	populationMass (int c) const =0
virtual const GrainSizeDistribution *	populationSizeDistribution (int c) const =0
virtual Range	populationSizeRange (int c) const =0
virtual double	totalMass () const =0

Protected Member Functions
	MultiGrainDustMix ()
void	addPopulation (const GrainPopulation *population)
void	addPopulation (GrainComposition *composition, GrainSizeDistribution *sizeDistribution, int numSizes, GrainPopulation::NormalizationType normType, double normValue)
double	getOpticalProperties (const Array &lambdav, const Array &thetav, Array &sigmaabsv, Array &sigmascav, Array &asymmparv, Table< 2 > &S11vv, Table< 2 > &S12vv, Table< 2 > &S33vv, Table< 2 > &S34vv, ArrayTable< 2 > &sigmaabsvv, ArrayTable< 2 > &sigmaabspolvv) override
size_t	initializeExtraProperties (const Array &lambdav) override
Protected Member Functions inherited from DustMix
	DustMix ()
virtual double	getOpticalProperties (const Array &lambdav, const Array &thetav, Array &sigmaabsv, Array &sigmascav, Array &asymmparv, Table< 2 > &S11vv, Table< 2 > &S12vv, Table< 2 > &S33vv, Table< 2 > &S34vv, ArrayTable< 2 > &sigmaabsvv, ArrayTable< 2 > &sigmaabspolvv)=0
void	informAvailableWavelengthRange (Range available)
virtual size_t	initializeExtraProperties (const Array &lambdav)
void	setupSelfAfter () override
Protected Member Functions inherited from MaterialMix
	MaterialMix ()
Configuration *	config () const
Random *	random () const
void	setupSelfBefore () override
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 ()
Protected Member Functions inherited from MultiGrainPopulationInterface
	MultiGrainPopulationInterface ()

Private Types
using	BaseType = DustMix
using	ItemType = MultiGrainDustMix

Private Attributes
EquilibriumDustEmissionCalculator	_calcEq
StochasticDustEmissionCalculator	_calcSt
bool	_multigrain
vector< double >	_mupopv
vector< double >	_normv
vector< const GrainPopulation * >	_populations
bool	_stochastic

Friends
class	ItemRegistry

Additional Inherited Members
Public Types inherited from DustMix
enum class	ScatteringMode { HenyeyGreenstein , MaterialPhaseFunction , SphericalPolarization , SpheroidalPolarization }
Public Types inherited from MaterialMix
enum class	DynamicStateType { None , Primary , Secondary , PrimaryIfMergedIterations }
enum class	MaterialType { Dust , Electrons , Gas }

Detailed Description

MultiGrainDustMix is an abstract class implementing a dust mix described by one or more grain populations, each with their own grain composition and size distribution, and with or without support for polarization by scattering. The class offers facilities to its subclasses to add dust grain populations to the dust mix during initial setup. Subsequently, the class uses this list of grain populations to calculate the optical properties requested by the DustMix base class, and to implement the additional functionality offered by multi-grain-population dust mixes, such as calculating emission from stochastically heated dust grains.

All grain populations added by the subclass must have a level of Mueller matrix support that matches the value returned by the scatteringMode() function (which may be overridden in the subclass). Specifically, for the HenyeyGreenstein scattering mode, none of the grain populations should offer a Mueller matrix. For the MaterialPhaseFunction and SphericalPolarization scattering modes, all of the grain populations should offer a Mueller matrix. If this is not the case, a fatal error will result.

Calculating representative grain properties

The getOpticalProperties() function calculates the basic representative grain properties expected by the DustMix base class from the following information obtained from the dust grain populations added by the subclass: the absorption efficiencies $Q^{\text{abs}}(\lambda ,a)$, the scattering efficiencies $Q^{\text{sca}}(\lambda ,a)$, the scattering phase function asymmetry parameter $g(\lambda ,a)$, the Mueller matrix coefficients $S^{\text{xx}}(\lambda ,a,\theta )$, the bulk density ${\rho }_{\text{bulk}}$ of the grain material, and the properly normalized grain size distribution per hydrogen atom $\mathrm{\Omega }(a)=(\frac{\text{d}{n}_{\text{D}}}{\text{d}a})/n_{\text{H}}$ in the range $[a_{\text{min}},a_{\text{max}}]$.

The properties are calculated for each wavelength ${\lambda }_{\ell }$ in the wavelength grid specified by the DustMix class. The values are obtained by integrating over the grain size distribution $\mathrm{\Omega }(a)$ using a builtin logarithmic grid and accumulating over all grain populations $c$, using the formulas listed below.

The absorption and scattering cross sections per hydrogen atom ${\varsigma }_{\ell }^{\text{abs}}$ and ${\varsigma }_{\ell }^{\text{abs}}$ for the $\ell$'th wavelength are calculated using

$${\varsigma }_{\ell }^{\text{abs}}=\sum _c{\int }_{a_{\text{min},c}}^{a_{\text{max},c}}{\mathrm{\Omega }}_c(a)Q_c^{\text{abs}}({\lambda }_{\ell },a)\pi a^2\text{d}a$$

and

$${\varsigma }_{\ell }^{\text{sca}}=\sum _c{\int }_{a_{\text{min},c}}^{a_{\text{max},c}}{\mathrm{\Omega }}_c(a)Q_c^{\text{sca}}({\lambda }_{\ell },a)\pi a^2\text{d}a.$$

The Mueller matrix coefficients provided by the grain population are assumed to be expressed as a cross section (in arbitrary units). They are thus integrated over the size distribution without again multiplying by the grain cross section, i.e. using

$$S_{\ell ,\text{t}}^{\text{xx}}=\sum _c{\int }_{a_{\text{min},c}}^{a_{\text{max},c}}{\mathrm{\Omega }}_c(a)S_c^{\text{xx}}({\lambda }_{\ell },a,{\theta }_{\text{t}})\text{d}a$$

The representative asymmetry parameter $g_{\ell }$ is averaged over the scattering cross section and thus calculated using

$$g_{\ell }=\frac{1}{{\varsigma }_{\ell }^{\text{sca}}}\sum _c{\int }_{a_{\text{min},c}}^{a_{\text{max},c}}{\mathrm{\Omega }}_c(a)g_c({\lambda }_{\ell },a)Q_c^{\text{sca}}({\lambda }_{\ell },a)\pi a^2\text{d}a.$$

The dust mass per hydrogen atom $\mu$ is calculated by integrating the bulk density over the size distribution,

$$\mu =\sum _c{\int }_{a_{\text{min},c}}^{a_{\text{max},c}}{\mathrm{\Omega }}_c(a){\rho }_{\text{bulk},c}\frac{4\pi }{3}{a}^3\text{d}a.$$

Calculating dust emission

The representative grain properties described above and offered by the public MaterialMix interface supported by this class are insufficient to accurately calculate dust emission spectra for the dust mixture. This is so because the emission spectrum is a nonlinear function of (among many other things) the grain size, and thus a single grain cannot accurately represent a population with a (potentialy large) range of grain sizes. Furthermore, smaller dust grains are often not in local thermal equilibrium, and instead are heated stochastically by individual photon absorption events. Modeling emission for these grains involves a temperature probability distribution rather than just an equilibrium temperature. The calculation needs calorimetric properties of the grain material in addition to optical properties.

It is numerically intractable to handle every possible grain size seperately. Instead, the MultiGrainDustMix class discretizes the grain size distribution for each type of grain material into a number of consecutive size bins (on a logarithmic scale), and calculates the optical and calorimetric properties of a representative grain for each of these bins. The number of bins for each type of grain material can be configured by the user. A larger number of bins improves the accuracy of the dust emission spectra. On the other hand, the calculation time scales roughly linearly with the number of bins.

The MultiGrainDustMix class uses one of two methods to calculate the emissivity of the dust mix:

• Assuming local thermal equilibrium for each representative grain (size bin): this method is fast but inaccurate because the equilibrium assumption is usually not justified. See the EquilibriumDustEmissionCalculator class for more information.
• Calculating a temperature probability distribution for each representative grain (size bin) to take into account stochastically heated grains: this second method is substantially more accurate but also much slower. See the StochasticDustEmissionCalculator class for more information.

Constructor & Destructor Documentation

MultiGrainDustMix()

MultiGrainDustMix::MultiGrainDustMix ( )

inlineprotected

Default constructor for abstract Item subclass MultiGrainDustMix : "a dust mix with one or more grain populations" .

Member Function Documentation

addPopulation() [1/2]

void MultiGrainDustMix::addPopulation ( const GrainPopulation *  population )

protected

This function adds the specified grain population to the dust mix. The receiving dust mix object retains a pointer to the specified GrainPopulation instance for later reference, but does not take ownership. The caller must ensure that the GrainPopulation instance lives at least as long as the dust mix, and that it is eventually destroyed (at the same time as or later than the dust mix).

addPopulation() [2/2]

void MultiGrainDustMix::addPopulation ( GrainComposition *  composition, GrainSizeDistribution *  sizeDistribution, int  numSizes, GrainPopulation::NormalizationType  normType, double  normValue  )

protected

This function adds the a grain population to the dust mix specified by its constituent components. The function creates a new GrainPopulation instance, passing its own function arguments to the GrainPopulation constructor. The receiving dust mix object claims ownership of the new GrainPopulation instance. The caller must guarantee that the lifetime of the specified composition and size distribution objects is as least as long as the lifetime of the receiving dust mix.

Refer to the description of the GrainPopulation constructor for more information on the arguments of this function.

emissivity()

Array MultiGrainDustMix::emissivity ( const Array &  Jv ) const

overridevirtual

This function returns the emissivity spectrum $({\epsilon }_{\lambda }{)}_{\ell }$ (radiated power per unit of solid angle and per hydrogen atom) of the dust mix (or rather of the corresponding mixture of representative grain populations) when embedded in the radiation field specified by the mean intensities $(J_{\lambda }{)}_k$. The input and output arrays are discretized on the wavelength grids returned by the Configuration::radiationFieldWLG() and Configuration::dustEmissionWLG() functions, repectively.

Depending on the type of emission calculation configured by the user, this function uses an instance of the EquilibriumDustEmissionCalculator or StochasticDustEmissionCalculator to calculate the emission spectrum. Refer to these classes for more information.

The behavior of this function is undefined if the simulation does not track the radiation field, because in that case setup does not precalculate the information on which this function relies.

Reimplemented from DustMix.

getOpticalProperties()

double MultiGrainDustMix::getOpticalProperties ( const Array &  lambdav, const Array &  thetav, Array &  sigmaabsv, Array &  sigmascav, Array &  asymmparv, Table< 2 > &  S11vv, Table< 2 > &  S12vv, Table< 2 > &  S33vv, Table< 2 > &  S34vv, ArrayTable< 2 > &  sigmaabsvv, ArrayTable< 2 > &  sigmaabspolvv  )

overrideprotectedvirtual

This function is invoked by the DustMix base class to obtain the representative grain optical properties for this dust mix. The first two arguments respectively specify the wavelength grid and (if applicable) the scattering angle grid on which the properties must be tabulated. The output arrays and tables will already have the appropriate size (corresponding to the input wavelength grids) when the function gets called.

For this class, this function integrates the optical properties over the grain size distribution for each of the grain populations added by a subclass as described in the class header, and stores the results into the corresponding output arrays. Also, the function returns the dust mass per hydrogen atom for the dust mix.

For the HenyeyGreenstein scattering mode, the Mueller matric tables remain untouched. For the MaterialPhaseFunction scattering mode, the function fills only the first table and leaves the other tables untouched. For the SphericalPolarization scattering mode, the function fills all four tables.

Implements DustMix.

hasStochasticDustEmission()

bool MultiGrainDustMix::hasStochasticDustEmission ( ) const

overridevirtual

This function returns true, indicating that this dust mix supports stochastic heating of dust grains for the calculation of secondary emission.

Reimplemented from MaterialMix.

initializeExtraProperties()

size_t MultiGrainDustMix::initializeExtraProperties ( const Array &  lambdav )

overrideprotectedvirtual

This function is invoked by the DustMix base class to precalculate additional dust properties required by this class. The argument specifies the wavelength grid on which the properties may be tabulated (i.e. the same grid as passed to the getOpticalProperties() function. The function returns the number of memory bytes allocated to store extra propertries.

The function discretizes the grain size distribution for each grain population added to this dust mix into a number of consecutive size bins (on a logarithmic scale), and obtains the relevant optical and calorimetric properties of a representative grain for each of these bins. The number of bins for each type of grain material can be configured by the user.

Depending on the type of emission calculation configured by the user, this function creates an instance of the EquilibriumDustEmissionCalculator or StochasticDustEmissionCalculator to store the relevant properties (and to actually calculate the emission spectra when requested).

Reimplemented from DustMix.

numPopulations()

int MultiGrainDustMix::numPopulations ( ) const

overridevirtual

This function returns the number of dust grain populations (with indices $c$) added to this dust mix by the subclass. Each grain population represents the combination of a grain composition, providing the optical and calorimetric properties of the grain material, and a grain size distribution with some normalization to specify the the amount of dust contained in the population. No grain size discretization has been applied to these populations.

Implements MultiGrainPopulationInterface.

population()

const GrainPopulation * MultiGrainDustMix::population

(

int

c

)

const

This function returns a read-only pointer to the grain population with index $c$. It is intended for use by the FragmentDustMixDecorator and should not be used for other purposes.

populationBulkDensity()

double MultiGrainDustMix::populationBulkDensity ( int  c ) const

overridevirtual

This function returns the bulk mass density ${\rho }_{\text{bulk}}$ of the grain material represented by the population with index $c$.

Implements MultiGrainPopulationInterface.

populationGrainType()

string MultiGrainDustMix::populationGrainType ( int  c ) const

overridevirtual

This function returns a brief human-readable identifier for the type of grain material represented by the population with index $c$. The identifier does not contain white space.

Implements MultiGrainPopulationInterface.

populationMass()

double MultiGrainDustMix::populationMass ( int  c ) const

overridevirtual

This function returns the dust mass ${\mu }_c$ per hydrogen atom for the population with index $c$.

Implements MultiGrainPopulationInterface.

populationNormalization()

double MultiGrainDustMix::populationNormalization

(

int

c

)

const

This function returns the size distribution normalization factor for the population with index $c$. It is intended for use by the FragmentDustMixDecorator and should not be used for other purposes.

populationSizeDistribution()

const GrainSizeDistribution * MultiGrainDustMix::populationSizeDistribution ( int  c ) const

overridevirtual

This function returns the grain size distribution object for the population with index $c$.

Implements MultiGrainPopulationInterface.

populationSizeRange()

Range MultiGrainDustMix::populationSizeRange ( int  c ) const

overridevirtual

This function returns the minimum and maximum grain sizes $a_{\text{min},c},a_{\text{max},c}$ for the population with index $c$.

Implements MultiGrainPopulationInterface.

totalMass()

double MultiGrainDustMix::totalMass ( ) const

overridevirtual

This function returns the total dust mass $\mu$ per hydrogen atom for all populations combined.

Implements MultiGrainPopulationInterface.

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

• MultiGrainDustMix.hpp