Using the estimated unreddened spectrum, we can address the issue of the energy distribution/flow in this source. Here, we shall assume a reddening of E(B-V)=0.61, leading to the unreddened spectrum sketched in Fig. 4. The (isotropic) luminosity in the 0.1-1000keV band is then
the NIR/optical/UV luminosity is
and the MIR/FIR luminosity is
The NIR/optical/UV luminosity given here is really a lower-limit since we
have assumed the minimum possible value for the reddening. These waveband
groups have been chosen on the basis of physical origin. The
X-ray/ 
-ray (i.e. 
and above) emission is
thought to be produced by non-thermal processes (e.g. Comptonization) in a
hot corona associated with the inner regions of an accretion disk. The
NIR/optical/UV ( 
) emissions have plausible origins
as thermal emission from the optically-thick accretion disk material. The
MIR/FIR ( 
) emission is likely to be thermal
emission from warm or hot dust associated with the dusty warm absorber and
putative molecular torus. Here we address the implications of the relative
magnitudes of these luminosities for the energetics of the source.
First, we will discuss some theoretical expectations. We will assume a
pure black hole model for the AGN emission, i.e. we will assume no
contribution to the observed `AGN' emission from a nuclear star-cluster or
starburst. As mentioned in the Introduction, it is believed that the inner
accretion disk possesses a hot optically-thin corona responsible for the
non-thermal X-ray/ -ray emission. Coronal models coupled with
spectral constraints imply that a large fraction of the energy that is
(locally) dissipated in the accretion disk is transported into the
corona, possibly in a magnetic form, before being radiated. The dominant
radiation process is thought to be inverse Compton scattering of soft
thermal (optical/UV) photons from the accretion disk. The emission of the
optical/UV seed photons is probably driven by high-energy irradiation from
the corona, thereby completing a self-sustaining feedback.
Suppose that the corona covers the entire disk surface and that almost all
of the accretion energy is released within the corona leading to the
X-ray/ -ray power-law emission. Approximately half of the primary
high-energy photons will strike the accretion disk. Approximately half of
the coronal
flux that strikes the disk will be thermalized and re-radiated
at optical/UV wavelengths, with the remaining half being `reflected'
(i.e. the photons undergo Compton backscattering or excite X-ray
fluorescence). Thus, this scenario would predict
where 
. Observationally, we infer there to be
significantly more NIR/optical/UV emission than this, 
(where approximate equality corresponds to the case where the reddening
takes its minimum allowed value, E(B-V)=0.61). There are several
possible interpretations. First, only a fraction of the (locally)
dissipated energy may be transported into the corona. However, it is
difficult to reconcile this with the X-ray spectrum given current coronal
models (e.g., Haardt & Maraschi 1991). Secondly, there may be another
optical/UV source in addition to the accretion disk such as a powerful
nuclear starburst. This is difficult to reconcile with the fact that the
optical continuum shown in Fig. 2a appears featureless and reddened to the
same degree as the BLR. Lastly, and most likely, the corona may not cover
the whole disk. It may be patchy or only exist in the innermost regions of
the disk. The regions of the accretion disk without an active corona would
still produce optical/UV emission via thermal emission resulting from
viscous dissipation.
For the minimal reddening case, E(B-V)=0.61, the MIR/FIR luminosity is comparable with luminosity in the whole of the rest of the spectrum. Within the dust-reprocessing paradigm, this is a troublesome result to understand unless the covering fraction of the dusty material is almost unity or the primary emission is anisotropic (with more primary radiation being emitted towards the dusty reprocessing material than towards us). A covering fraction of unity is implausible given our understanding of the geometry of a Seyfert nucleus. However, if we suppose that E(B-V)>0.61, then the IR/optical/UV luminosity can greatly exceed the above value thereby alleviating the problem of the MIR/FIR production.