Input Parameters¶

Summary¶

Here we list the input parameters summary

Parameter Name	Type	Default	Description
`debug`	int	0	Debug switch.
`model`	int	0	Reflection model or pure scattering.
`nmaxmain`	int	15	Number of maximum main iteration steps.
`nmaxrte`	int	200	Number of maximum radiative transfer iteration steps.
`nfrt`	int	5000	Number of energy bins.
`nmurt`	int	10	Number of angle grids.
`ndrt`	int	200	Number of depth grids.

Plasma

Parameter Name	Type	Default	Description
`it_temp`	int	99	Maximum iteration steps for thermal equilibrium.
`temp_gas`	float	1e8	Initial gas temperature.
`temp_gas_unit`	str	‘k’	Unit of initial gas temperature.
`nh`	float	1.0e15	Hydrogen density.
`zeta`	float	3.0	Log10 of ionization parameter.

Illumination

Parameter Name	Type	Default	Description
`inci_type`	str	‘powerlaw’	Type of corona illumination.
`gamma`	float	2.0	Photon index or Blackbody temperature in eV.
`hcut`	float	300e3	High energy cut-off for cut-off power law or electrons temperture.
`ktbb_nth`	float	0.1e3	Blackbody temperature when incident type is Comptonization source.
`inmu`	float	0.7	Incidence angle.
`sbot`	int	0	Switch of bottom illumination [Thermal disk radiation].
`ktbb`	float	350.0	Temperature of Thermal disk radiation.
`fx_frac`	float	1.0	Flux of top illumiantion over total illumination.
`inci_file`	str	‘incident/nthcomp_g2.0_t60.txt’	Incident spectrum file name [Necessary for type of incident is “file”].

Elemental Abundances (Relative to Hydrogen)

Parameter Name	Type	Default	Description
`h`	float	1.0	Abundance of Hydrogen. This is the reference element.
`he`	float	1.0	Abundance of Helium relative to Hydrogen.
`li`	float	0.0	Abundance of Lithium relative to Hydrogen.
`be`	float	0.0	Abundance of Beryllium relative to Hydrogen.
`ba`	float	0.0	Abundance of Barium relative to Hydrogen.
`c`	float	1.0	Abundance of Carbon relative to Hydrogen.
`n`	float	1.0	Abundance of Nitrogen relative to Hydrogen.
`o`	float	1.0	Abundance of Oxygen relative to Hydrogen.
`f`	float	0.0	Abundance of Fluorine relative to Hydrogen.
`ne`	float	1.0	Abundance of Neon relative to Hydrogen.
`na`	float	0.0	Abundance of Sodium relative to Hydrogen.
`mg`	float	1.0	Abundance of Magnesium relative to Hydrogen.
`al`	float	0.0	Abundance of Aluminum relative to Hydrogen.
`si`	float	1.0	Abundance of Silicon relative to Hydrogen.
`p`	float	0.0	Abundance of Phosphorus relative to Hydrogen.
`s`	float	1.0	Abundance of Sulfur relative to Hydrogen.
`cl`	float	0.0	Abundance of Chlorine relative to Hydrogen.
`ar`	float	1.0	Abundance of Argon relative to Hydrogen.
`k`	float	0.0	Abundance of Potassium relative to Hydrogen.
`ca`	float	1.0	Abundance of Calcium relative to Hydrogen.
`sca`	float	0.0	Abundance of Scandium relative to Hydrogen.
`ti`	float	0.0	Abundance of Titanium relative to Hydrogen.
`va`	float	0.0	Abundance of Vanadium relative to Hydrogen.
`cr`	float	0.0	Abundance of Chromium relative to Hydrogen.
`mn`	float	0.0	Abundance of Manganese relative to Hydrogen.
`fe`	float	1.0	Abundance of Iron relative to Hydrogen.
`co`	float	0.0	Abundance of Cobalt relative to Hydrogen.
`ni`	float	1.0	Abundance of Nickel relative to Hydrogen.
`cu`	float	0.0	Abundance of Copper relative to Hydrogen.
`zn`	float	0.0	Abundance of Zinc relative to Hydrogen.

Path Group

Parameter Name	Type	Default	Description
`kernelpath`	str	‘kernel_exact5000’	Compton scattering Redistribution function file, the energy bins need to be as same in model.
`dataenv`	str	‘data’	Atomic database and Compton heating-cooling file.
`op_spec`	str	spec.dat	Output spectrum file.
`op_temp`	str	temp.dat	Output temperature file.
`op_inte`	str	inte.dat	Output intensity file.
`op_log`	str	model.log	Output log file.
`op_emis`	str	emis.dat	Output emissivity file (not used for now).
`op_abund`	str	abud.fits	Output abundance file.

Detailed Description¶

Grids¶

debug,model

DAO support the pure scattering model with constant gas temperature along the vertical depth when model set at 1, and normal reflection model when model set at 0.

Debug mode is opened when debug switch set at 1. Energy, angle and depth grids and other useful inforamtion will be printed to a file when it’s open.

nmaxmain,nmaxrte

nmaxrte controls the maximum iteration steps for radiative transfer. Considering the calculation time and convergence, we set 200 as default steps.

nmaxmain controls the maximum iteration steps between radiative transfer and XSTAR. We set 15 as default value

nfrt,nmurt,nfrt

These parameters define the resolution of depth, energy, and angle grids. We don’t recommend user reduce the resolution of depth and energies. The photons are more easier to be scattered in its own energy and the line emission haven’t enough resolution when nfrt is small.

Plasma¶

it_temp,temp_gas,temp_gas_unit

XSTAR need number of iterations to get thermal equilibrium, it-temp is same with nlimd in XSTAR, we don’t recommend user change this parameter. temp-gas, temp-gas-unit define the initial gas temperature and its unit, they are only important when you run constant-temperature pure scattering model.

nh

Hydrogen density in cm−3. The DAO version 1.0 only support for density less than 10^18 cm−3. Specify atom data table will be needed when density large than that value [Kallman et al., 2021].

zeta

Initial value of the log (base 10) of the model ionization parameter at the innermost shell. The [Tarter et al., 1969] form is used:

(1)¶\[\xi = \frac{4\pi F_x}{n_h}\]

This value will be re-calculated after radiation field update.

Illumination¶

There are many parameters control the illumination, and different meaning of each parameters when we assume different type of illumination. In this section, I’ll sort the parameters by differnt incident type.

Bottom blackbody¶

In DAO, the radiation from the bottom of the disk is modeled as a blackbody source. The parameter sbot controls this boundary condition: if sbot=1, bottom illumination is enabled; otherwise, the bottom boundary is assumed to be zero.

When sbot=1, ktbb defines the blackbody temperature, and fx_frac determines the partition of the total flux between the top and bottom surfaces. First, the total ionizing flux (Fx) is calculated via Eq. (1). The fluxes for the top and bottom boundaries are then derived as:

\[F_\mathrm{top} = F_x \times \mathrm{fx\_frac}, \quad F_\mathrm{bot} = F_x \times (1 - \mathrm{fx\_frac})\]

Power law or Cut-off power law¶

This formulation applies when inci_type is set to powlaw or cutoff. The spectral shape is defined as:

\[F(E) = A \times E^{-\Gamma+1} \exp\left(-E/E_{cut}\right) , \quad \mathrm{or} \quad F(E) = A \times E^{-\Gamma+1} \]

where:

Gamma (\(\Gamma\)): The photon index.
hcut (\(E_{cut}\)): The high-energy cutoff.
A: normalization factor, defined by Eq.(1)

Currently, the model does not implement a low-energy cutoff.

Blackbody¶

This formulation applies when inci_type is set to blackbody. The spectral shape is defined as a blackbody with temperature set at Gamma [eV].

nthcomp¶

This formulation applies when inci_type is set to nthcomp. The spectral shape is defined by Zdziarski et al. [1996].

Gamma: Photon index.
hcut: Electron temperatures \(kT_e\) [eV].
ktbb_nth: Blackbody temperatures \(kT_{bb}\) [eV].

comptt¶

Added in version 1.1.3: This incident spectrum type was introduced in version 1.1.3.

This formulation applies when inci_type is set to comptt. The spectral shape is defined by Titarchuk [1994]. This configuration assumes a disk geometry with the optical depth fixed at \(\tau = 1.0\).

Gamma: Wien temperature [eV].
hcut: Plasma temperature [eV].

file¶

This mode is activated when inci_type is set to file. In this configuration, the spectral shape is determined by an external user-provided file.

Consequently, the inci_file parameter is mandatory and must specify a valid path to your spectrum file.

File Format Specification

The spectrum file must consist of a 3-line header followed by the data rows (total \(3+n\) rows).

1. Header Lines (First 3 rows)

Row 1: Number of energy bins (\(n\)).
Row 2: Spectrum Unit Flag.
- 0: \(\mathrm{erg \cdot cm^{-2} \cdot s^{-1} \cdot erg^{-1}}\)
- 1: \(\mathrm{photons \cdot cm^{-2} \cdot s^{-1} \cdot erg^{-1}}\)
- 2: \(\mathrm{erg^2 \cdot cm^{-2} \cdot s^{-1} \cdot erg^{-1}}\) (\(E F_E\))
Row 3: Energy Unit Flag.
- 0: eV
- 1: keV

2. Data Block

Following the header, the file must contain 2 columns (Energy, Flux) for the remaining \(n\) rows.

Abundances¶

Atomic abundances for elements H through Zn are initialized using a predefined table. The adopted values are based on Grevesse et al. [1996].

The user can change the abundance of individual elements, relative to that table.