general information about the model
relxill is a new reflection model, which can be readily used in common X-ray data analysis tools such as isis, xspec, or sherpa. It joins forces of the xillver reflection code (Garcia et al., 2010, 2011, 2013) and the relline ray tracing code (Dauser et al., 2010, 2013). The striking new feature is that for each point on the disk the proper xillver-reflection spectrum is chosen for each relativistically calculated emission angle. The implications of this improvement and more details regarding the model are provided in Garcia & Dauser et al. (2014, ApJ, 782, 76) and Dauser & Garcia et al. (2014, MNRAS, 444, L100).
The current version has been completely re-written, leading to a more stable and faster model evaluation. Moreover, for some of the model flavors it is possible to use a multi-zone disk. This update solves the issue pointed out in some publications that the input spectrum changes throughout the disk due to GR energy shifts. Therefore results for the lamp post flavor relxill models will slightly differ to the previous version, while all other models produce identical results. The changes are mainly compensated by a decrease of the cutoff energy around 10%.
relxill on GitHub: you can also follow the development of the model on GitHub and download the model from there (https://github.com/thdauser/relxill/)
As of version 1.3.0, the relxill also includes a variant which allows for an ionization gradient. Either the shape of the gradient can be fitted as a power law, or the gradient is predicted from the alpha disk density profile.
The figure on the left shows the spectra for three different levels of ionization (left panel) with the associated ionization gradient (right panel). The dashed line shows the radius of maximal ionization.
current version of the model: [v1.3.3]
First download all necessary files given in the download section. It is not necessary to download all reflection tables. If those are required, a warning is issued when executing the model.
To compile the model, put all of the downloaded files into a directory, and unpack them:
tar xfz relxill_tables.tgz tar xfz relxill_model_v1.3.3.tgz
In order to compile the model, it is recommended that you call the provided compile-script by executing:
chmod u+x ./compile_relxill.sh ./compile_relxill.sh2019.jj.high_density_agns_jiachen_190121.pdf
In this way the path to the tables will be correctly set in the model code, allowing you to properly load the model from any location. If you have a Mac OSX and setting the table paths fails, you might need to edit the file and un-comment line marked for "Mac OSX".
ALTERNATIVE: If you don't want to use this compile script, you can also set the path to the tables by setting the environment variable "RELXILL_TABLE_PATH" to the directory which contains the tables.
Standard relativistic reflection model, modeling the irradiation of the accretion by a broken power law emissivity. Different flavors are for an incident spectrum by either the standard high-energy cutoff powerlaw or an nthcomp Comptonization continuum (Cp).
The relativistic reflection model for the lamp post geometry, again for an incident cutoff powerlaw or nthcomp spectrum (Cp). The disk is split in multiple zones, which see a different incident spectrum due to relativistic energy shifts of the primary spectrum.
normal reflection models, given for different incident spectra; powerlaw with high-energy cutoff (xillver) or with a nthcomp Comptonization (xillverCp).
simple line model, available in the coronal and lamp post (lp) geometry
similar to the line models, but now as a convolution model being able to convolve any reflection
Model including an ionization gradient. Depending on the setting of the parameter ion_grad_type, the gradient can be either modeled empirically as power law, or is predicted assuming a simple alpha disk (Shakura & Sunyaev, 1973). Detailed information is given in the parameters section. Also includes a velocity of the primary source.
Same as the standard reflection models (xillver, relxill, relxilllp) but allowing a higher density for the accretion disk (between 1015 to 1019 cm-3). However, the high-energy cutoff is fixed at 300 keV at the moment.
In the following, a list of all model parameters ia given. Some parameters have a special meaning if their value is negative, as also indicated in the list below.
spin of the black hole in dimensionless units, negative values mean the accretion disk is counter-rotating with respect to the black hole
inner and outer radius of the accretion disk in gravitational radii. Can also be given in units of the ISCO, when it is set to negative values.
inclination towards the system with respect to the normal to the accretion disk
the emissivity for the coronal flavor models is given as r-Index1 between Rin and Rbr and r-Index2 between Rbr and Rout. Rbr is measured in gravitational radii, but can also be given in units of the ISCO if given in negative values.
Height of the primary source above the black hole in gravitational radii. Can be given in units of the event horizon if set to negative values.
Velocity of the primary source, in units v/c. Allowed values range form 0 to 0.99.
reflection fraction, defined in the frame of the primary source as ratio of intensity emitted towards the disk compared to escaping to infinity (see Dauser+2016 for more details). If set to a negative value, only the reflected component is returned.
switch, which set to 0 allows to fit the reflection freely and if set to 1 fixed to the predicted value of the current parameter configuration in the lamp post geometry. If set to 2, the model behaves similar to 1, but is displaying information on the calculated reflection fraction, strength, and fraction of photons falling into the black hole. Additionally the grav. redshift from the observer to the primary source is given.
Ionization of the accretion disk, ranging from 0 (neutral) to 4.7 (heavily ionized). In case of an ionization gradient, it specifies either the ionization at the inner edge (power law type) or the maximal ionization at (11/9)²Rin (alpha type).
The iron abundance of the material in the accretion disk (in units of solar abundance).
Power law index of the incident spectrum.
Parameter describing the observed high energy cutoff Ecut of the primary spectrum. In case of the nthcomp input spectrum it is given as electron temperature in the corona (kTe). Important: As Ecut is given in the frame of the observer, the value at the primary source has to be calculated by multiplying with the redshift factor (see fixReflFrac=2).
The density of the accretion disk (in cm-3) given in logarithmic units. Models not containing this parameter are calculated for a fixed density of 1015 cm-3.
redshift to the source
Specifies the ionization gradient. If set to 1, it will be modeled as power law. Setting it to 2 means it is calculated by assuming the density profile of an alpha disk, peaking at (11/9)²Rin (see logxi above). For convenience, setting it to 0 means constant ionization.
In case of a power law ionization gradient (ion_grad_type=1) this parameter specifies the index of the power law such that xi = r-xi_index with logxi giving the ionization at Rin .