Spectrum Configuration

Finally, the spectrum configuration tells TARDIS information needed for spectrum generation (see Spectrum Generation):

type	object
properties
start	The lower wavelength limit of the frequency-bin grid used for the real- and virtual-packet histograms.
	type	quantity
stop	The upper wavelength limit of the frequency-bin grid used for the real- and virtual-packet histograms.
	type	quantity
num	Number of bins used to build the spectrum
	type	number
	multipleOf	1.0
method	The method to generate the final spectrum
	type	string
	enum	integrated, virtual, real
	default	virtual
integrated	type	object
	default
	properties
	points	Number of impact parameters p used in the calculation of the integrated spectrum
		type	number
		default	1000
	interpolate_shells	Number of shells on which the formal integral quantities are interpolated. For -1 no interpolation is used. The default is to use twice the number of computational shells but at least 80.
		type	number
		default	0
	compute	Which method the formal_integral will be computed with. It defaults to the Numba version, but it can be run on NVIDIA Cuda GPUs. GPU will make it only run on a NVIDIA Cuda GPU, so if one is not available it will raise an error. Automatic first tries to find an acceptable GPU, and if none is found it will run on the CPU.
		type	string
		default	CPU
	additionalProperties	False
virtual	type	object
	default
	properties
	tau_russian	For optical depths greater tau_russian russian rouletting is used for the v-packets
		type	number
		default	10.0
	survival_probability	Probability for not terminating the packet path between 0 and 1
		type	number
		default	0.0
	enable_biasing	If True bias v-packet emission based on the electron scattering optical depth
		type	boolean
		default	False
	virtual_packet_logging	If True, enable virtual packet logging output
		type	boolean
		default	False
	additionalProperties	False

start and stop are given as wavelength values with units. They define the boundaries of the frequency grid used for the real- and virtual-packet histograms and for the generated spectrum. The histogram range is independent of the range that controls which R-packets may spawn virtual packets. num specifies the number of bins used to build the spectrum and must be given as an integer. TARDIS produces the spectrum via three different methods. For more information on these methods, visit the pages below:

• real: Basic Spectrum Generation

• virtual: Virtual Packet Scheme

• integrated: Formal Integral Method

The three methods can be specified when plotting the spectrum (see the quickstart guide for an example of this).

The following example shows how to edit variables for the different methods.

spectrum:
        start: 500 angstrom
        stop: 20000 angstrom
        num: 1000
        method: integrated
        integrated:
                points: 2000
                interpolate_shells: 100
        virtual:
                tau_russian: 15
                survival_probability: 0.1
                enable_biasing: True
                virtual_packet_logging: True

The virtual-packet spawn range is configured separately in the montecarlo section. It determines the wavelength range of R-packets that can spawn a virtual-packet volley. The limits are converted to frequency internally, so the lower wavelength limit corresponds to the upper frequency limit:

montecarlo:
        virtual_spectrum_spawn_range:
                start: 1000 angstrom
                end: 10000 angstrom

One can also change these parameters as they wish by reading in the configuration file and editing them before running the simulation (see Reading a Configuration).

Warning

As of now, the method argument serves no purpose other than adding the integrated spectrum to the HDF output when “integrated” is used as the method (see How to Store Simulations to HDF).