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The SKIRT project
advanced radiative transfer for astrophysics
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The SKIRT project
advanced radiative transfer for astrophysics
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#include <ElectronMix.hpp>
Public Member Functions | |
| double | defaultTemperature () const |
| bool | hasPolarizedScattering () const override |
| bool | hasScatteringDispersion () const override |
| bool | includePolarization () const |
| bool | includeThermalDispersion () const |
| double | indicativeTemperature (const MaterialState *state, const Array &Jv) const override |
| void | initializeSpecificState (MaterialState *state, double metallicity, double temperature, const Array ¶ms) 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 |
| bool | 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 |
| double | sectionAbs (double lambda) const override |
| double | sectionExt (double lambda) const override |
| double | sectionSca (double lambda) const override |
| vector< StateVariable > | specificStateVariableInfo () 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 | hasResonantScattering () const |
| virtual bool | hasStochasticDustEmission () 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 vector< SnapshotParameter > | parameterInfo () const |
| virtual bool | scatteringEmulatesSecondaryEmission () const |
| virtual const Array & | sectionsAbs (double lambda) const |
| virtual const Array & | sectionsAbspol (double lambda) const |
| 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 |
Protected Member Functions | |
| ElectronMix () | |
| void | setupSelfBefore () 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 () |
| Protected Member Functions inherited from Item | |
| Item () | |
Private Types | |
| using | BaseType |
| using | ItemType |
Private Attributes | |
| ComptonPhaseFunction | _cpf |
| double | _defaultTemperature |
| DipolePhaseFunction | _dpf |
| bool | _hasDispersion |
| bool | _includePolarization |
| bool | _includeThermalDispersion |
Friends | |
| class | ItemRegistry |
Additional Inherited Members | |
| Public Types inherited from MaterialMix | |
| enum class | DynamicStateType { None , Primary , Secondary , PrimaryIfMergedIterations } |
| enum class | MaterialType { Dust , Electrons , Gas } |
The ElectronMix class describes the material properties for a population of electrons. Electrons do not absorb photons. They do, however, significantly scatter photons. This process is described by Compton scattering, which converges to Thomson scattering at low photon energies. It is meaningful to implement both processes, because the calculations for Compton scattering are substantially slower than those for Thomson scattering. If requested by the user, polarization by scattering is fully supported in both regimes.
Compton and Thomson scattering
For wavelengths shorter than 10 nm, this class models Compton scattering, which features a wavelength-dependent cross section and phase function, and which causes the photon energy (wavelength) to change during the interaction. This process is implemented through the ComptonPhaseFunction class; see that class for more information.
For wavelengths longer than 10nm, the scattering process can be described by elastic and wavelength-independent Thomson scattering. The scattering cross section is given by the well-known Thomson cross section (a constant) and the phase function is that of a dipole. Consequently, this class calls on the DipolePhaseFunction class to implement Thomson scattering; see that class for more information.
The transition point between Compton and Thomson scattering can be justified as follows. For wavelengths much longer than 10 nm, the expression for the Compton cross section becomes numerically unstable. This could be solved by using a series expansion approximation at longer wavelengths. However, at a wavelength of 10 nm, the Compton cross section has approached the Thomson constant to within less than 0.05 per cent. It thus seems reasonable to transition to the much faster Thomson scattering at that wavelength point.
Thermal dispersion
By default, this class assumes that all electrons are at rest in the local frame (i.e., there is no movement other than the bulk velocity of the spatial cell containing the electrons). If the includeThermalDispersion configuration flag is enabled (and the simulation mode is panchromatic), a random thermal motion corresponding to the local temperature is added when performing a scattering interaction. The dispersion is not taken into account to determine the scattering cross section, because that value does not vary significantly for small wavelength shifts (and it does not vary at all for Thomson scattering).
If the electron mix is associated with an ImportedMedium and the importTemperature flag for the medium is enabled, the local dispersion temperature is obtained from the imported file. Otherwise, the value configured for the defaultTemperature property is used instead, resulting in a constant temperature across space.
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inlineprotected |
Default constructor for concrete Item subclass ElectronMix: "a population of electrons".
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inline |
This function returns the value of the discoverable double property defaultTemperature: "the default temperature of the electron population".
This property represents a physical quantity of type "temperature".
The minimum value for this property is "[3".
The maximum value for this property is "1e8]".
The default value for this property is given by the conditional value expression "1e4".
This property is relevant only if the Boolean expression "Panchromatic&includeThermalDispersion" evaluates to true after replacing the names by true or false depending on their presence.
This property is displayed only if the Boolean expression "Level2" evaluates to true after replacing the names by true or false depending on their presence.
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overridevirtual |
This function returns the value of the includePolarization flag, indicating whether the material mix supports polarization during scattering events or not.
Reimplemented from MaterialMix.
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overridevirtual |
This function returns true when thermal dispersion is enabled and/or support for Compton scattering has been turned on (based on the simulation's wavelength range), indicating that in those cases a scattering interaction for the electron mix may (and usually does) adjust the wavelength of the interacting photon packet. If both thermal dispersion and support for Compton scattering are disabled, the function returns false.
Reimplemented from MaterialMix.
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inline |
This function returns the value of the discoverable Boolean property includePolarization: "include support for polarization".
The default value for this property is given by the conditional value expression "false".
This property is displayed only if the Boolean expression "Level2" evaluates to true after replacing the names by true or false depending on their presence.
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inline |
This function returns the value of the discoverable Boolean property includeThermalDispersion: "include thermal velocity dispersion".
The default value for this property is given by the conditional value expression "false".
This property is relevant only if the Boolean expression "Panchromatic" evaluates to true after replacing the names by true or false depending on their presence.
This property is displayed only if the Boolean expression "Level2" evaluates to true after replacing the names by true or false depending on their presence.
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overridevirtual |
This function returns an indicative temperature of the material mix when it would be embedded in a given radiation field. The implementation in this class ignores the radiation field and returns the temperature driving the thermal velocity dispersion for the medium component in the relevant spatial cell, or zero if thermal velocity dispersion is not enabled for this material mix. Because nothing in the simulation changes the electron temperature, this value corresponds to the temperature defined by the input model at the start of the simulation.
Reimplemented from MaterialMix.
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overridevirtual |
This function initializes any specific state variables requested by this material mix except for the number density. See the description of the MaterialMix::initializeSpecificState() function for more information.
For this class, in case the electron mix has thermal dispersion, the function initializes the temperature to the specified imported temperature, or if this is not available, to the user-configured default temperature for this electron mix.
Reimplemented from MaterialMix.
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overridevirtual |
This function returns the electron mass.
Implements MaterialMix.
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overridevirtual |
This function returns the fundamental material type represented by this material mix, which is MaterialType::Electrons.
Implements MaterialMix.
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overridevirtual |
This function returns the absorption opacity \(k^\text{abs}=n\varsigma^\text{abs}\), which is trivially zero for electrons.
Implements MaterialMix.
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overridevirtual |
This function returns the extinction opacity \(k^\text{ext}=k^\text{abs}+k^\text{sca}\) for the given material state and wavelength. The photon properties are not used because the cross section does not depend on the polarization state of the incoming photon packet.
Implements MaterialMix.
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overridevirtual |
This function returns the scattering opacity \(k^\text{sca}=n\varsigma^\text{sca}\) for the given material state and wavelength. The photon properties are not used because the cross section does not depend on the polarization state of the incoming photon packet.
Implements MaterialMix.
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overridevirtual |
This function calculates the contribution of the medium component associated with this electron mix to the peel-off photon luminosity, polarization state, and wavelength shift for the given wavelength, geometry, material state, and photon properties. The contributions to the Stokes vector components are stored in the I, Q, U, V arguments, which are guaranteed to be initialized to zero by the caller. If there is wavelength shift, the new wavelength value replaces the incoming value of the lambda argument.
If includePolarization has been set to true, the function supports polarization; otherwise it does not.
Reimplemented from MaterialMix.
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overridevirtual |
This function performs a scattering event on the specified photon packet in the spatial cell and medium component represented by the specified material state and the receiving electron mix. If includePolarization has been set to true, the function supports polarization; otherwise it does not.
Reimplemented from MaterialMix.
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overridevirtual |
This function returns the absorption cross section per electron \(\varsigma^{\text{abs}}_{\lambda}\), which is trivially zero for all wavelengths \(\lambda\).
Implements MaterialMix.
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overridevirtual |
This function returns the total extinction cross section per electron \(\varsigma^{\text{ext}}_{\lambda} = \varsigma^{\text{abs}}_{\lambda} + \varsigma^{\text{sca}}_{\lambda}\). Because the absorption cross section is trivially zero, this equals the scattering cross section.
Implements MaterialMix.
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overridevirtual |
This function returns the scattering cross section per electron \(\varsigma^{\text{sca}}_{\lambda}\) which varies with the wavelength \(\lambda\) for high energies and converges to the constant Thomson cross section at low energies.
Implements MaterialMix.
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overrideprotectedvirtual |
This function initializes the DipolePhaseFunction instance held by this class.
Reimplemented from SimulationItem.
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overridevirtual |
This function returns a list of StateVariable objects describing the specific state variables used by the receiving material mix. See the description of the MaterialMix::specificStateVariableInfo() function for more information.
For the electron mix class, the returned list always includes the specific state variable for number density and, in case the electron mix has thermal dispersion, it also includes the specific state variable for temperature.
Implements MaterialMix.