`RELXILL`v0.3a

`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.

v0.3a: **New major version of
the relxill model.** The biggest change is that the
normalization is now defined in a different way, namely directly
following the xillver normalization and accounting properly for
the reflection fraction. Additionally, the value of the reflection
fraction for the lamp post geometry is now more accurately
determined, by also taking the boosting of the primary radiation
into account. The xillver table has changed as well, allowing now
to fit the photon index down to gamma = 1. In addition to these
substantial changes a few minor bug fixes have been applied.

### 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). All information can also be found in this pdf: download

norm: | defined as the normalization of xillver divided by
the ionization parameter |

refl_frac: | reflection fraction (relxill): calculated between 20 and 40 keV |

refl_frac: | reflection fraction (relxilllp): calculated directly from the lamp post geometry |

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

angleon: | 0: angle averaging (see below for more information) |

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). The only exception is the additional parameter
**angleon**. If set to **0**, the relxill model acts like a
simple `RELCONV x XILLVER`, hence using only the angle averaged
reflection spectra and then applying the relativistic smear. However,
if set to **1**, it acts as described above: For each point on the
disk the proper xillver-reflection spectrum is chosen for each
relativistically calculated emission angle. Note that due to the
relativistic effects the emission angle is generally not equal to the
inclination angle and therefore this more complicated approach is
necessary. Moreover, as the angular effects are properly treated, no
"guess" regarding a limb brightening or darkening law is needed
anymore. Hence, unless you
really know what you are doing: Leave **angleon=1**. It is
definitely the exacter model (no matter what your chi2 value is
telling you)!

### Download

To install, please download the following files:

last changes | in version | |

relxill_code.tgz | 2015-10-14 | v0.3a |

tables.fits.tgz (warning: 849MB) | 2015-10-14 | v0.3a |

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.