On this page you can find files derived from my work that may be of some use to others. Please feel free to contact me with any questions or suggestions.

Xspec Table Models for Reprocessing in a Simplified AGN Torus      list below:

The model tables available here were computed with a new Monte Carlo radiative transfer code BORUS, presented in my Ph.D. thesis, Baloković et al. (2018), and Baloković et al. (2019). Clicking the model name below will open its description, basic instructions, and links to files. I plan to provide models with a range of different geometries and physical assumptions in the future. If you let me know that you are interested in using these models for modeling of AGN spectra, I can get back to you with any updates.

Assumptions relevant to all model tables available below, unless explicitly specified otherwise: (1) the X-ray source is at the geometric center and emits a spectrum that is either a phenomenological cutoff power law (CPL), i.e. F(E) ~ E exp(-E/Ecut), or a more realistic coronal continuum (nthComp, as represented in Xspec); (2) gas is assumed to be cold and neutral; (3) Compton scattering neglects the internal structure of the atomic scatterers, so that the Compton shoulder would be comparable to older models which employed such a simplification; (4) fluorescent line emission and the reprocessed continuum are calculated self-consistently; (5) tables represent only the reprocessed component, so the line-of-sight component can be added separately in Xspec (see the example .xcm files below).

  • Uniform Density Sphere, CPL Intrinsic Continuum: borus01

  • Uniform Density Sphere, nthComp Intrinsic Continuum: borus11

  • Uniform Density Sphere with Polar Cutouts, CPL Intrinsic Continuum: borus02

    The reprocessing medium is assumed to be a sphere with conical cutouts at both poles, approximating a torus with variable covering factor. Half-opening angle of the polar cutouts, θtor, measured from the symmetry axis toward the equator, ranges from zero (full covering, equivalent to the borus01 model above) to 83o (corresponding to disk-like 10% covering). Note that the covering factor is just the cosine of θtor. Gas is assumed to be uniformly distributed, with elemental abundances of the Sun, except for the abundance of iron, which is a variable parameter. The line-of-sight component (intrinsic continuum absorbed by NH,los) can have a different column density than the average column density of the torus (NH,tor) in order to account for clouds passing in/out of the line of sight. Unless this model is used for fitting a large quantity of broadband X-ray data, fitting for all model parameters is not recommended.

    The model is similar to, and broader than, the torus model of Brightman & Nandra (2011), also known as BNtorus in the literature. borus02 has additional free parameters (Ecut, AFe), additional chemical elements included, calculation extending to higher energies and line-of-sight component separated out -- allowing its application to a wider array of different AGN types. Also, note that the torus model is now known not to be correct (Liu & Li 2015, Paltani & Ricci 2017, Baloković et al. 2018, Buchner et al. 2019), so its replacement with borus02 is recommended even if additional features are not required. A manual describing the details of the model and its usage in modeling X-ray spectra will become available in the near future. Simple examples of model setup in Xspec are given below. Please see Baloković et al. (2018) for examples of using this model for parameter constraints.

    Due to the limited photon statistics of the calculated spectra, the tables available below are not recommended for use on the highest-quality CCD-based soft X-ray data, or grating spectra. The smoothness of the model spectra is sufficient for NuSTAR data (FWHM~400 eV) and medium-quality CCD-based data (FWHM~140 eV). Ongoing calculations will improve the statistical quality, so that future versions of these tables will be sufficient for spectra with high energy resolution enabled by X-ray calorimeters on XRISM and Athena (FWHM below 10 eV).

    • latest set of Xspec model tables:
          borus02_v170323a.fits -- table with Ctor = cos(θtor) and cos(θinc) as parameters
          borus02_v170323b.fits -- table with Ctor = cos(θtor) and θinc as parameters
          borus02_v170323c.fits -- table with θtor and θinc as parameters 
          borus02_v170323k.fits -- same as table "a", but only the reprocessed continuum
          borus02_v170323l.fits -- same as table "a", but only the reprocessed lines
    • free parameters:
          1 = photon index, Γ = 1.4--2.6
          2 = high-energy cutoff, Ecut/keV = 20--2000
          3 = torus column density, log10(NH,tor/cm-2) = 22.0--25.5
          4 = torus covering factor, Ctor = cos(θtor) = 0.1--1.0, or θtor/deg. = 0--84
          5 = cosine of inclination, cos(θinc) = 0.05--0.95, or θinc/deg. = 19--87
          6 = relative abundance of iron, AFe/AFe,Sun = 0.01--10.0
          7 = redshift
          8 = normalization of the intrinsic spectrum (photons s-1cm-2keV-1 at 1 keV)
    • example Xspec .xcm files:
          NOTE: The files below assume that the abundance of iron is Solar. For non-unity AFe/AFe,Sun, the line-of-sight absorption component
            would need to be replaced with one having a free AFe/AFe,Sun parameter, e.g. vphabs or tbabs.
          borus02_afe1_abscont.xcm -- l.o.s. + reprocessed components, NH,tor independent of NH,los
    •     borus02_afe1_abscont_NHlinked.xcm -- l.o.s. + reprocessed components, NH,tor equal to NH,los


    Comparison of the borus02 model to other publicly available models for X-ray reprocessing in AGN tori, in terms of assumed geometry and model parameters. From Baloković et al. (2018).


  • Uniform Density Sphere with Polar Cutouts, nthComp Intrinsic Continuum: borus12

Sketches and Video Clips      list below:

Graphics I made for illustrative purposes in papers and presentation slides. If they are useful for your presentations, any credit would be appreciated. Note that some versions have been published in journals, which should therefore be referenced accordingly. Most of the material was created and edited using Gimp, TinkerCad and LibreOffice.

  • Approximate Torus Geometry with a Variable Covering Factor

  • Multi-wavelength Constraints on AGN Geometry (3D Model of IRAS 09104+4109)

Figures and Data      list below:

Selected figures from my published papers (adapted for better legibility in presentations), and the data behind some of them.

  • Mrk 421: Distribution of Fractional Variability Amplitude in Quiescence

Research-related Code      list below:

Scripts I wrote for my own work, that could potentially be useful to others.

  • Energy Binning Above a Minimum SNR per Bin: snrgrppha

Mislav Baloković -- last updated 2019 Nov 25