galapy.ActiveGalacticNucleus

The ActiveGalacticNucleus module implements the AGN contribution by loading templates from Fritz et al., 2006.

Templated emission is divided into 3 components:

Accretion disk around the central SMBH (accessible through the instance variable AGN().disk)
Scattered emission by the surrounding dusty torus (accessible through the instance variable AGN().scat)
Thermal dust emission associated to the dusty torus (accessible through the instance variable AGN().ther)

The templates are computed accounting for the variation of 6 structural parameters:

the covering angle of the torus \(\Gamma\), expressed in terms of half the aperture-angle with respect to the equatorial plane:

\[\Theta = 90^\circ - \dfrac{\Gamma}{2}\]
the dust density distribution in spherical coordinates:

\[\rho \propto r^\beta e^{- \alpha|\cos\theta|}\]

parameterized in terms of \(\alpha\) and \(\beta\);
the ratio \(R^\text{AGN}_\text{torus}\) between the maximum to minimum radii of the dusty torus;
the optical depth \(\tau^\text{AGN}_{9.7}\) at \(9.7\ \mu m\);
the viewing angle \(\Psi^\text{AGN}_\text{los}\), i.e. the angle between the rotation axis and the line-of-sight. (note that by assuming the unifed AGN model, with \(\Psi^\text{AGN}_\text{los} = 90^\circ\) the geometry of the object corresponds to a type 1 AGN, while \(\Psi^\text{AGN}_\text{los} = 0^\circ\) to a type 2 AGN)

The above parameters in our implementation are controlled through the above parameters following the original naming schema used by the authors and summarized in the following table:

Parameter	Key	\(N_\text{values}\)	Values
\(\Theta\)	`ct`	3	(\(20^\circ,\ 40^\circ,\ 60^\circ\))
\(\alpha\)	`al`	4	(\(0,\ 2,\ 4,\ 6\))
\(\beta\)	`be`	5	(\(-1,\ -0.75,\ -0.5,\ -0.25,\ 0\))
\(R^\text{AGN}_\text{torus}\)	`rm`	5	(\(10,\ 30,\ 60,\ 100,\ 150\))
\(\tau^\text{AGN}_{9.7}\)	`ta`	8	(\(0.1,\ 0.3,\ 0.6,\ 1,\ 2,\ 3,\ 6,\ 10\))
\(\Psi^\text{AGN}_\text{los}\)	`ia`	10	\(0^\circ\) to \(90^\circ\) with step \(10^\circ\)

Which results in 24000 available templates. The user can nevertheless set the parameters to whatever value and the template whose parameters are closer to the selection is chosen.

Functions

`agn_build_params`(fAGN, **kwargs)	Standard function for building the parameters dictionary of class AGN()
`find_template_par`(key, value)	Given a key-value pair returns the parameter corresponding to key included in the template-library and closest to value

Classes

AGN(lmin, lmax[, pad, fAGN, do_Xray])

AGN component class This class implements the templated emission from an Active Galactic Nucleus within the galaxy.

galapy.ActiveGalacticNucleus.find_template_par(key, value): Given a key-value pair returns the parameter corresponding to key included in the template-library and closest to value

galapy.ActiveGalacticNucleus.agn_build_params(fAGN, **kwargs): Standard function for building the parameters dictionary of class AGN()

class galapy.ActiveGalacticNucleus.AGN(lmin, lmax, pad=16, fAGN=0.001, do_Xray=True, **kwargs)

AGN component class This class implements the templated emission from an Active Galactic Nucleus within the galaxy. We use templates from Fritz et al., 2006 to model the AGN emission normalized at build time. The total emission is then rescaled to a user-provided total emission.

The final emission can be expressed as

\[L_\text{AGN}(\lambda) = \dfrac{f_\text{AGN}}{1-f_\text{AGN}}L_\text{AGN}^\text{norm}(\lambda)\cdot L_\text{ref}\]

where \(f_\text{AGN}\) is the fraction of the reference emission, \(L_\text{ref}\), radiated by the AGN and \(L_\text{AGN}^\text{norm}\) is the normalized total templated emission.

Parameters:

lmin (float) – minimum and maximum values of the wavelength-domain. The original templates are computed within the 10-10^7 Angstrom interval. At build time this domain is extended with pad padding values before and after the limits of the template’s wavelength domain to match the requested limits.
lmax (float) – minimum and maximum values of the wavelength-domain. The original templates are computed within the 10-10^7 Angstrom interval. At build time this domain is extended with pad padding values before and after the limits of the template’s wavelength domain to match the requested limits.
pad (integer) – number of padding values to match the requested wavelength domain
fAGN (float) – fraction of the total reference emission
do_Xray (bool) – If True compute the X-ray template along with the closest template for the lower energy part of the spectrum (default is True)

Keyword Arguments:

ct (scalar) – the covering angle of the torus \(\Gamma\), expressed in terms of half the aperture-angle with respect to the equatorial plane
al (scalar) – parameter regulating the dust density distribution in spherical coordinates, corresponds to \(\alpha\)
be (scalar) – parameter regulating the dust density distribution in spherical coordinates, corresponds to \(\beta\)
ta (scalar) – the optical depth at \(9.7\ \mu m\)
rm (scalar) – the ratio between the maximum to minimum radii of the dusty torus
ia (scalar) – the inclination angle between the rotation axis of the AGN torus and the line of sight. Note that by assuming the unifed AGN model, with ia = 90 the geometry of the object corresponds to a type 1 AGN, while ia = 0 to a type 2 AGN.

load_template(): Loads the template corresponding to the current parameters (mostly intended for internal usage).

compute_X_template(): Pre-computes the not-normalized and not-bolometric-corrected X-ray spectrum.

X_bolometric_correction(Lref)

Computes the bolometric correction from Duras et al., 2020 (Eq. 2):

\[\dfrac{L_\text{bol}^\text{AGN}}{L_\text{X}^\text{AGN}} \approx 10.96\;\biggl[1 + \biggl(\dfrac{\log L_\text{bol}^\text{AGN}/L_\odot}{11.93}\biggr)^17.79\biggr]\]

Parameters:: Lref (scalar) – Bolometric luminosity of the AGN in units of solar luminosities \(L_\odot\)
Returns:: Value of the bolometric correction.
Return type:: scalar

set_parameters(fAGN=None, **kwargs)

Sets the internal parameters defining the emission coming from the AGN. All the parameters that are not passed to this function will be left to the value they already have.

Parameters:

fAGN (scalar) – sets the normalization of the templated emission. The parameters fAGN provides the amount of energy radiated by the AGN in units of some other emission contributor, typically the energy radiated by dust in the same band.
**kwargs – These are the parameters passed to function find_template_par. Used to find the nearest AGN emission template in the Fritz et al. (2006) library.

emission(ll, Lref)

Computes the emission coming from the AGN adding the X-ray part if the internal variable do_Xray has been set to True at build time

Parameters:

ll (sequence) – wavelength list or array or iterable
Lref (float) – bolometric reference luminosity used to compute the bolometric correction of the high-energy part of the spectrum

Returns:

Luminosity per unit wavelength in units of solar luminosities emitted by the AGN.

Return type:

numpy-array