FilePolarizedPointSource Class Reference

#include <FilePolarizedPointSource.hpp>

Inheritance diagram for FilePolarizedPointSource:

Classes
struct	Tables

Public Member Functions
int	dimension () const override
string	filename () const
bool	hasVelocity () const override
void	launch (PhotonPacket *pp, size_t historyIndex, double L) const override
double	luminosity () const override
LuminosityNormalization *	normalization () const
double	positionX () const
double	positionY () const
double	positionZ () const
double	specificLuminosity (double wavelength) const override
double	symmetryX () const
double	symmetryY () const
double	symmetryZ () const
Vec	velocity () const override
double	velocityX () const
double	velocityY () const
double	velocityZ () const
Range	wavelengthRange () const override
Public Member Functions inherited from Source
virtual int	dimension () const =0
virtual bool	hasVelocity () const =0
virtual void	launch (PhotonPacket *pp, size_t historyIndex, double L) const =0
virtual double	luminosity () const =0
virtual void	prepareForLaunch (double sourceBias, size_t firstIndex, size_t numIndices)
double	sourceWeight () const
virtual double	specificLuminosity (double wavelength) const =0
double	wavelengthBias () const
WavelengthDistribution *	wavelengthBiasDistribution () 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 WavelengthRangeInterface
virtual	~WavelengthRangeInterface ()
virtual Range	wavelengthRange () const =0
Public Member Functions inherited from VelocityInterface
virtual	~VelocityInterface ()
virtual Vec	velocity () const =0

Protected Member Functions
	FilePolarizedPointSource ()
void	setupSelfAfter () override
void	setupSelfBefore () override
Protected Member Functions inherited from Source
	Source ()
void	informAvailableWavelengthRange (Range available, string itemType)
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 SourceWavelengthRangeInterface
	SourceWavelengthRangeInterface ()
Protected Member Functions inherited from WavelengthRangeInterface
	WavelengthRangeInterface ()
Protected Member Functions inherited from VelocityInterface
	VelocityInterface ()

Private Types
using	BaseType = Source
using	ItemType = FilePolarizedPointSource

Private Attributes
WavelengthDistribution *	_biasDistribution
VelocityInterface *	_bvi
string	_filename
LuminosityNormalization *	_normalization
double	_positionX
double	_positionY
double	_positionZ
ContSED *	_sed
Direction	_sym
double	_symmetryX
double	_symmetryY
double	_symmetryZ
Tables	_tables
double	_velocityX
double	_velocityY
double	_velocityZ
double	_xi

Friends
class	ItemRegistry

Detailed Description

FilePolarizedPointSource represents a primary source limited to a single point in space and emitting polarized radiation with an axisymmetric angular dependence. The Stokes vector components of the emitted radiation, as a function of wavelength and inclination angle cosine, are loaded from a user-provided file. The bolometric output is characterized by a LuminosityNormalization object configured in the ski file. The class furthermore offers user-configured properties to specify the position of the point source, the orientation of the symmetry axis of the angular dependence, and a "bulk" velocity.

Inclination angle

For the purposes of this class, the inclination angle \(\theta\) is defined as the angle between the user-configured symmetry axis \(\bf{s}\) and the propagation direction \(\bf{k}\) of the emitted photon packet. The inclination cosine values given in the input file must conform to this convention.

In formula form, assuming that both directions \(\bf{s}\) and \(\bf{k}\) are given as unit vectors, the inclination angle cosine simply is \(\cos\theta=\bf{s}\cdot\bf{k}\).

Reference direction

The components of a Stokes vector (and hence the polarization angle derived from it) are specified relative to some reference direction \(\bf{d}\) which must be perpendicular to the propagation direction \(\bf{k}\) of the emitted photon packet. For the purposes of this class, the reference direction is taken to be the orthogonal projection of the user-configured symmetry axis \(\bf{s}\) on the plane perpendicular to the propagation direction \(\bf{k}\). The Stokes vector values given in the input file must conform to this convention.

In formula form, assuming that the propagation direction \(\bf{k}\) is given as a unit vector, the (unnormalized) orthogonal projection of \(\bf{s}\) on the plane with normal \(\bf{k}\) is given by \(\bf{d} = \bf{s} - (\bf{k}\cdot\bf{s})\bf{k}\). Rather than the reference direction itself, the implementation instead uses the normal \(\bf{n}\) to the reference plane, which is defined as the plane through both the reference direction and the propagation direction. The normalized normal vector \(\bf{n}\) is obtained from

\[ \bf{n} = \frac{\bf{d} \times \bf{k}}{||\bf{d} \times \bf{k}||} = \frac{\bf{s} \times \bf{k}}{||\bf{s} \times \bf{k}||} \]

after substitution of the above expression for \(\bf{d}\). If the symmetry axis and the propogation direction are (anti)parallel, the normal vector \(\bf{n}\) is undefined and the emitted radiation is taken to be unpolarized.

Input file format

As indicated in the introduction above, the user-provided input file tabulates the Stokes vector components \(I,Q,U,V\) of the emitted radiation as a function of wavelength and inclination angle cosine. In other words, the input file represents a two-dimensional table with four values in each entry. All information is bundled in a single binary file using the SKIRT stored table format (see StoredTable).

All quantities are specified in internal SKIRT units:

• The inclination axis specifies cosine grid points in the range [-1, 1], in increasing order. This corresponds to angular values in the range [180 deg, 0 deg]; note the reverse order. In case the outer grid points are not equal to -1 and 1, the Stokes vector values for cosines outside of the grid are simply clamped to the corresponding outer grid point. This implies that, even if the emission pattern is symmetric around the 90 deg inclination, it is not sufficient to provide values for half of the inclination range. Instead, the reflected pattern must be included as well.
• The wavelength axis specifies the wavelength grid points expressed in meter, in increasing order. For wavelengths outside of this grid, the emission is considered to be zero.
• The Stokes vector components \(I,Q,U,V\) are expressed in Watt per meter, with a scale factor that is abitrary but identical for the four components and across all Stokes vectors in the file. It is important to ensure that the quantities are expressed per unit of wavelength, as opposed to per unit of frequency or energy. Other than that, the precise units are irrelevant because of the arbitrary scaling.

Example python script

Below is an excerpt from a python script used to create an appropiate input file for this class from the information in a set of text files. In particular, the script shows how to create the file in SKIRT stored table format using the PTS function pts.storedtable.io.writeStoredTable. It also illustrates some of the conversions that may need to be performed.

import numpy as np
from pts.storedtable.io import writeStoredTable
 
# read the inclination grid (in deg); range is 0..90 deg
theta = ...
numTheta = len(theta)
 
# read the energy grid (in keV)
E = ...
numE = len(E)
 
# read the Stokes vector components (in ph/s/keV) for each inclination bin
Ie = np.zeros((numTheta, numE))
Qe = np.zeros((numTheta, numE))
Ue = np.zeros((numTheta, numE))
for i in range(numTheta):
    Ie[i], Qe[i], Ue[i] = ...
 
# add symmetrical inclination range and reverse the order so that range becomes 180..0 deg
theta = np.concatenate((180 - theta, theta[::-1]))
Ie = np.concatenate((Ie, Ie[::-1]))
Qe = np.concatenate((Qe, Qe[::-1]))
Ue = np.concatenate((Ue, Ue[::-1]))
 
# convert inclination from deg to cosine in range -1..1
costheta = np.cos(theta * np.pi/180)
 
# convert energy in keV to wavelength in m
h = 6.62606957e-34
c = 2.99792458e8
q = 1.602176634e-19
lam = 1e-3 * h * c / q / E
 
# convert flux from per-energy flavor to per-wavelength flavor,
# with arbitrary normalization so that values are on the order of 1
Ilam = Ie / lam**3 / 1e35
Qlam = Qe / lam**3 / 1e35
Ulam = Ue / lam**3 / 1e35
 
# reverse spectral range so that wavelengths are in increasing order
lam = np.flip(lam)
Ilam = np.flip(Ilam, axis=1)
Qlam = np.flip(Qlam, axis=1)
Ulam = np.flip(Ulam, axis=1)
 
# create zero V component
Vlam = np.zeros_like(Ilam)
 
# write stored table
writeStoredTable(inputname + ".stab",
                 ['costheta','lambda'], ['1','m'], ['lin','log'], [costheta,lam],
                 ['I','Q','U','V'], ['W/m','W/m','W/m','W/m'], ['log','lin','lin','lin'], [Ilam,Qlam,Ulam,Vlam])

This item type is displayed only if the Boolean expression "Level2" evaluates to true after replacing the names by true or false depending on their presence.

When an item of this type is used, the names provided by the conditional value expression "Dimension2,ContSED" are inserted into the name sets used for evaluating Boolean expressions.

Constructor & Destructor Documentation

FilePolarizedPointSource()

FilePolarizedPointSource::FilePolarizedPointSource ( )

inlineprotected

Default constructor for concrete Item subclass FilePolarizedPointSource : "a primary point source with a polarized spectrum read from file" .

Member Function Documentation

dimension()

int FilePolarizedPointSource::dimension ( ) const

overridevirtual

This function returns the dimension of the point source, which depends on the (lack of) symmetry of its geometry.

Implements Source.

filename()

string FilePolarizedPointSource::filename ( ) const

inline

This function returns the value of the discoverable string property filename : "the name of the stored table file listing the Stokes vector components" .

hasVelocity()

bool FilePolarizedPointSource::hasVelocity ( ) const

overridevirtual

This function returns true if the velocity of the source is nonzero.

Implements Source.

launch()

void FilePolarizedPointSource::launch ( PhotonPacket *  pp, size_t  historyIndex, double  L  ) const

overridevirtual

This function causes the photon packet pp to be launched from the source using the given history index and luminosity contribution. The function samples a wavelength and a propagation direction from the spectral and angular dependencies derived from the input file, constructs proper objects for angular distribution, polarization profile and bulk velocity, and finally emits the photon packet with these properties.

Implements Source.

luminosity()

double FilePolarizedPointSource::luminosity ( ) const

overridevirtual

This function returns the luminosity \(L\) (i.e. radiative power) of the source integrated over the wavelength range of primary sources (configured for the source system as a whole).

Implements Source.

normalization()

FilePolarizedPointSource::normalization ( ) const

inline

This function returns the value of the discoverable item property normalization : "the type of luminosity normalization for the source" .

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

positionX()

FilePolarizedPointSource::positionX ( ) const

inline

This function returns the value of the discoverable double property positionX : "the position of the point source, x component" .

This property represents a physical quantity of type "length" .

The default value for this property is given by the conditional value expression "0" .

When a value is entered for this property, the names provided by the conditional value expression "positionX:Dimension3" are inserted into the name sets used for evaluating Boolean expressions.

positionY()

FilePolarizedPointSource::positionY ( ) const

inline

This function returns the value of the discoverable double property positionY : "the position of the point source, y component" .

This property represents a physical quantity of type "length" .

The default value for this property is given by the conditional value expression "0" .

When a value is entered for this property, the names provided by the conditional value expression "positionY:Dimension3" are inserted into the name sets used for evaluating Boolean expressions.

positionZ()

FilePolarizedPointSource::positionZ ( ) const

inline

This function returns the value of the discoverable double property positionZ : "the position of the point source, z component" .

This property represents a physical quantity of type "length" .

The default value for this property is given by the conditional value expression "0" .

setupSelfAfter()

void FilePolarizedPointSource::setupSelfAfter ( )

overrideprotectedvirtual

This function warns the user if this source's intrinsic wavelength range does not fully cover the configured wavelength range.

Reimplemented from SimulationItem.

setupSelfBefore()

void FilePolarizedPointSource::setupSelfBefore ( )

overrideprotectedvirtual

This function reads the user-provided input file and caches the relevant information.

Reimplemented from SimulationItem.

specificLuminosity()

double FilePolarizedPointSource::specificLuminosity ( double  wavelength ) const

overridevirtual

This function returns the specific luminosity \(L_\lambda\) (i.e. radiative power per unit of wavelength) of the source at the specified wavelength, or zero if the wavelength is outside the wavelength range of primary sources (configured for the source system as a whole) or if the source simply does not emit at the wavelength.

Implements Source.

symmetryX()

FilePolarizedPointSource::symmetryX ( ) const

inline

This function returns the value of the discoverable double property symmetryX : "the direction of the positive symmetry axis, x component" .

This property represents a physical quantity of type "length" .

The default value for this property is given by the conditional value expression "0" .

When a value is entered for this property, the names provided by the conditional value expression "symmetryX:Dimension3" are inserted into the name sets used for evaluating Boolean expressions.

symmetryY()

FilePolarizedPointSource::symmetryY ( ) const

inline

This function returns the value of the discoverable double property symmetryY : "the direction of the positive symmetry axis, y component" .

This property represents a physical quantity of type "length" .

The default value for this property is given by the conditional value expression "0" .

When a value is entered for this property, the names provided by the conditional value expression "symmetryY:Dimension3" are inserted into the name sets used for evaluating Boolean expressions.

symmetryZ()

FilePolarizedPointSource::symmetryZ ( ) const

inline

This function returns the value of the discoverable double property symmetryZ : "the direction of the positive symmetry axis, z component" .

This property represents a physical quantity of type "length" .

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

velocity()

Vec FilePolarizedPointSource::velocity ( ) const

overridevirtual

This function implements the VelocityInterface interface. It returns the bulk velocity of this source, as configured by the user.

Implements VelocityInterface.

velocityX()

FilePolarizedPointSource::velocityX ( ) const

inline

This function returns the value of the discoverable double property velocityX : "the bulk velocity of the point source, x component" .

This property represents a physical quantity of type "velocity" .

The minimum value for this property is "[-100000 km/s" .

The maximum value for this property is "100000 km/s]" .

The default value for this property is given by the conditional value expression "0" .

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.

When a value is entered for this property, the names provided by the conditional value expression "Panchromatic&velocityX:Dimension3" are inserted into the name sets used for evaluating Boolean expressions.

velocityY()

FilePolarizedPointSource::velocityY ( ) const

inline

This function returns the value of the discoverable double property velocityY : "the bulk velocity of the point source, y component" .

This property represents a physical quantity of type "velocity" .

The minimum value for this property is "[-100000 km/s" .

The maximum value for this property is "100000 km/s]" .

The default value for this property is given by the conditional value expression "0" .

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.

When a value is entered for this property, the names provided by the conditional value expression "Panchromatic&velocityY:Dimension3" are inserted into the name sets used for evaluating Boolean expressions.

velocityZ()

FilePolarizedPointSource::velocityZ ( ) const

inline

This function returns the value of the discoverable double property velocityZ : "the bulk velocity of the point source, z component" .

This property represents a physical quantity of type "velocity" .

The minimum value for this property is "[-100000 km/s" .

The maximum value for this property is "100000 km/s]" .

The default value for this property is given by the conditional value expression "0" .

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.

wavelengthRange()

Range FilePolarizedPointSource::wavelengthRange ( ) const

overridevirtual

This function returns the wavelength range for this source. Outside this range, all luminosities are zero. This source's wavelength range is determined as the intersection of the simulation's source wavelength range (obtained from the simulation configuration) and the intrinsic wavelength range of the spectrum read from the input file.

This function implements the SourceWavelengthRangeInterface interface.

Implements WavelengthRangeInterface.

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

• FilePolarizedPointSource.hpp