RELXILL_NK is a relativistic reflection model that is based on RELXILL and extends it to non-Kerr spacetimes. Please follow the instructions below carefully in order to ensure a properly working version of the model. This model is designed and tested to work within the X-ray spectral fitting software XSPEC. 1.6.3 is the current version of the model.
If you are using the RELXILL_NK model in your work please cite the following:
- Bambi et al., Testing the Kerr black hole hypothesis using X-ray reflection spectroscopy, The Astrophysical Journal, 842, 76 (2017)
- Abdikamalov et al., Public Release of RELXILL_NK: A Relativistic Refletion Model for Testing Einstein's Gravity, The Astrophysical Journal, 878, 91 (2019)
- Installing the model:
-
Run following to execute the compile script:
chmod u+x compile_relxill.sh -
Execute
./compile_relxill.sh
- Setting up the model environment:
-
Most importantly the model needs to know where the pre-calculated tables are located. By default it assumed that they are in the current working directory.
-
The recommended approach is to set the environment variable "RELXILL_TABLE_PATH" to the path where the tables are stored.
That means for a csh shell putting a line like the following in the .cshrc:
setenv RELXILL_TABLE_PATH /home/user/data/relline_tables/
or for a bash shell in .bashrc:
export RELXILL_TABLE_PATH='/home/user/data/relline_tables/'
-
Loading the model in XSPEC:
From the directory where the model has been installed, the model can simply be loaded inside XSPEC:
lmod relxill_nk . -
For questions and bug reports, please contact relxill_nk@fudan.edu.cn
-
To work with the model, one would require certain FITS files.
-
Xillver table (which is the same as for relxilll and can be downloaded from the webpage of relxill model).
-
FITS file of the transfer functions of the Johannsen metric are available here:
NOTE: When using FITS file of \alpha_{22} or \epsilon_{3}, please change#define RELTABLE_NG 40to#define RELTABLE_NG 20in the filerelbase.h -
The models with lamppost/ring-like/disk-like coronae geometry require another FITS file (currently can be provided upon request, we will provide a link to download at a later stage).
-
-
The parameter def_par_type specifies the spacetime metric. One should freeze the value of def_par_type to the one associated to the non-Kerr metric of interest.
For example,
def_par_type = 1 specifies Johanssen metric with non-zero$\alpha_{13}$
def_par_type = 11 specifies KRZ metric with non-zero$\delta_{1}$ -
The parameter mdot_type specifies the accretion rate in Eddington units and controls the thickness of the accretion disk according to the model proposed by Taylor and Reynolds. NOTE: The FITS file for disk with finite thickness are only available for the Johanssen metric with non-zero
$\alpha_{13}$ .
mdot_type = 0 is infinitesimally thin disk
mdot_type = 1 is disk of finite thickness which has a mass accretion rate of 5% of the Eddington limit
mdot_type = 2 is disk of finite thickness which has a mass accretion rate of 10% of the Eddington limit
mdot_type = 3 is disk of finite thickness which has a mass accretion rate of 20% of the Eddington limit
mdot_type = 4 is disk of finite thickness which has a mass accretion rate of 30% of the Eddington limit -
The range of deformation parameters are not uniform and depend on the spin of the black hole, since XSPEC requires a uniform range of the parameter values we scale the deformation parameter values in the range [-1, 1]. We provide pyhton scripts (unscale.py and unscale_batch.py) to obtain the actual (unscaled) values of the deformation parameters after the fitting.
