RXToPo

Reprocessed emission from a dusty torus with a polar hollow cone.

Developed at the Instituto de Estudios Astrofísicos, Universidad Diego Portales, Santiago, Chile, with the support of ANID Beca Doctorado Nacional 21211606.

Schematic of the RXToPo geometry: a central black hole and corona, a dusty torus of inner radius r and outer radius R, and a polar hollow cone, with the inclination angle θ, the torus half-opening angle φ and the cone outer boundary ξ_o marked. — Geometry of the RXToPo model. Figure from Dimopoulos, Ricci & Paltani (2025), ApJ 992, 64.

Downloads

Component	Description	File	Size
ALL	All photons (continuum + reprocessed)	rxtopo_all_.mod.gz	1.2 GB
RPRC	All reprocessed photons	rxtopo_rpr_.mod.gz	863.8 MB
SCAT	Scattered photons only (no fluorescence)	rxtopo_sct_.mod.gz	834.2 MB
FLUO	Fluorescent photons only	rxtopo_flo_.mod.gz	182.0 MB
CNT	Transmitted continuum	rxtopo_cnt_.mod.gz	1.0 GB

How the models are computed

Input continuum	Cutoff power-law; cutoff energy fixed at 200 keV
Energy range	0.3 – 300 keV
Spectral resolution	ΔE = 20 eV (4 eV retained in the Fe Kα, Fe Kβ/edge and Ni Kα regions)
Composition	Lodders et al. (2009) abundances
Physical processes	Rayleigh scattering, Compton scattering on bound electrons, dust grain interactions

Spectral components

5 spectral components are provided, based on the interaction history of the photons.

`all` ALL	All photons (continuum + reprocessed)
`rpr` RPRC	All reprocessed photons
`sct` SCAT	Scattered photons only; no fluorescence emission
`flo` FLUO	Fluorescence emission (including subsequent scattering)
`cnt` CNT	Transmitted continuum (no interaction with the medium)

ALL = CNT + RPRC and RPRC = SCAT + FLUO

Parameters

All spectral components of RXToPo share the same free parameters.

Parameter	Range	Description
`PhoIndex`	1.6 – 2.4	Photon index Γ of the input cutoff power-law continuum
`NHeq`	log 22.0 – 25.5	Equatorial hydrogen column density of the dusty torus
`CFtor`	0.1 – 0.9	Covering factor of the torus; ratio of inner cutout radius r to outer radius R, with CFtor = sin(φ)
`NHpol`	log 22.0 – 24.0	Hydrogen column density of the polar hollow cone, measured along the inner cone surface
`Inclination`	1 – 89 deg	Viewing angle θ of the system (1 = face-on, 89 = edge-on), sampled in steps of 2°
`z`	0 – 5	Redshift
`norm`	0 – 1e20	Photon flux of the input continuum at 1 keV (ph keV⁻¹ cm⁻² s⁻¹)

Note on the polar cone opening angle. The hollow cone is collimated by the torus. Its inner boundary angle is set to ξ_max = φ + 1° (to avoid overlap), where φ = arcsin(CFtor). The cone has a fixed angular width of 10°, so its outer boundary is ξ_o = ξ_max + 10°. The cone column density NHpol is a free parameter independent of CFtor.

Note on the total sky coverage. The total covering fraction of obscuring material is not equal to CFtor alone. The polar cone also contributes solid angle coverage and should be accounted for when computing the total covering factor.

Usage in XSPEC

Load a downloaded table as a model component.

Typical usage with the ALL table

model tbabs * atable{rxtopo_all_.mod.gz}

Reprocessed component with additional soft emission and line components

model tbabs * (atable{rxtopo_rpr_.mod.gz} + apec + zgauss)

The tables can be loaded while still gzip-compressed, as shown above. XSPEC decompresses them into memory each time they are read, so if you fit repeatedly it is faster to decompress once with gunzip and point XSPEC at the resulting .mod file.

How to cite

If these models are useful in your work, please cite the paper in which they are presented:

Dimopoulos, G., Ricci, C., & Paltani, S. 2025, ApJ, 992, 64. doi:10.3847/1538-4357/adfd52

@ARTICLE{2025ApJ...992...64D,
       author = {{Dimopoulos}, G. and {Ricci}, C. and {Paltani}, S.},
        title = "{The Study of the Circumnuclear Environment of Accreting Supermassive Black Holes with Realistic X-Ray Spectral Models}",
      journal = {\apj},
     keywords = {Supermassive black holes, Radiative transfer simulations, X-ray active galactic nuclei, 1663, 1967, 2035, High Energy Astrophysical Phenomena},
         year = 2025,
        month = oct,
       volume = {992},
       number = {1},
          eid = {64},
        pages = {64},
          doi = {10.3847/1538-4357/adfd52},
archivePrefix = {arXiv},
       eprint = {2605.06794},
 primaryClass = {astro-ph.HE},
       adsurl = {https://ui.adsabs.harvard.edu/abs/2025ApJ...992...64D},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

The model files are archived on Zenodo under CC BY 4.0 — doi:10.5281/zenodo.22082873

Line-of-sight NH calculator

A command-line utility for computing the line-of-sight column density NH_los for the RXToPo and RXagn1 models using RefleX v3. It provides a simple front-end to the REFLEXINO procedure described in Appendix B of Dimopoulos, Ricci & Paltani (2025), hiding the internal complexity of RefleX and enabling quick calculations for individual sources or batch runs.

View on GitHub →

References

Found a problem, or need a configuration that isn't here? Email me — I'm happy to help.