`RELXILL`v0.4a

`RELXILL` is a brand new model, joining forces of
the `XILLVER` reflection code (link;
Garcia et al., 2010, 2011, 2013) and the `RELLINE` 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). See also this
pdf for a short information on all
models and their parameters. A full list of changes of previous
versions can be found here.

v0.4a: A bug was found in the
reflection fraction in v0.3a. **Any reflection fraction obtained with
v0.3a can therefore unfortunately not be trusted and has to be
re-computed with new version **. We would like to stress that this does
not affect the spectral shape, but only the value of the reflection
fraction obtained from the fit. The only exception is if the reflected
and primary spectrum was fixed using `fixReflFrac=1` and
therefore also the complete spectral shape was affected by this
bug.

Along with the fix of the reflection fraction, the normalization
of `relxill` was also revised. It is now consistently set to
follow the `xillver` normalization, but including all
relativistic effects. Additionally the angleon parameter was removed
from the parameter list (setting it to angleon=1).

Due to several
misunderstandings, the definition of the reflection fraction was
revised. In order to provide a concise and detailed overview, this was
done as a research note (submitted to A&A). It can be found here: http://arxiv.org/abs/1601.03771.

### General Information

By installing the
new `RELXILL` model, all previous implementations of the
`relline`-like and `relconv`-like models are
automatically installed, too. These models are completely
identical to the ones from the `RELLINE` installation (hence,
no additional installation of relline is necessary to get the
previous functionalities).

### Usage and Parameters

The`RELXILL`model now includes by default the irradiating power law source. It's strength can be set by the parameter

`refl_frac`. This reflection fraction is defined as the ratio of photons that hit the disk to those that reach infinity. Due to strong light bending effects, this value can easily be larger than 1. More details can be found in Dauser+2014. Note, that for a negative value of

`refl_frac`, only the reflection compontent will be returned (similar to the pexrav model definition). The detailed definition of the reflection fraction can be found here (Research Note submitted to A&A): link. All information about the parameters of all

`relxill`flavor models can also be found in this pdf: download

norm: | defined as the normalization of xillver, including relativistic effects |

refl_frac: | reflection fraction (relxill): calculated between 20 and 40 keV (see RN for details) |

refl_frac: | reflection fraction (relxilllp): calculated directly from the lamp post geometry (see RN for details) |

Ecut: | cutoff energy in keV (the same for the power law and the reflection spectrum) |

1: take angles properly into account | |

fixReflFrac: | 0: free reflection fraction (determined by
the refl_frac parameter) |

1: fix reflection fraction to the lamp post value (i.e.,
the parameter refl_frac has NO meaning in this case) | |

2: free, (same as 0:), but now the reflection fraction is displayed on the screen |

The meaning of the parameters is the same as for the separate models (see relline description). Moreover, as the angular effects are properly treated, no "guess" regarding a limb brightening or darkening law is needed anymore.

### Download

To install, please download the following files:

last changes | in version | |

relxill_code.tgz | 2016-01-18 | v0.4a |

tables.fits.tgz (warning: 849MB) | 2016-01-18 | v0.4a |

The installation is similar to the relline model (look here). Note that you can use the environment variable RELLINE_TABLES to point to the complete set of provided tables, including the xillver table.

### A Comparison between `RELXILL` and the angle averaged approach

`RELXILL`(standard parameters: logxi=2, gamma=2, index=3, spin=0.99). Middle: Ratio between relxill and the conventional relconv*xillver. Right: Relativ distribution of flux for different emission angles. Note the angle averaged approach, which is commonly used, assumes a flat distribution here.

The code here is still in *BETA-test!* Please contact
me if
you find bugs or encounter problems with the model.