We present a study of the central engine in the broad-line radio galaxy 3C 109 .
To investigate the immediate surrounding of this accreting , supermassive black hole , we perform a multi-epoch broad-band spectral analysis of a joint NuSTAR / XMM observation ( 2017 ) , an archival XMM observation ( 2005 ) and the 105-month averaged Swift -BAT data .
We are able to clearly separate the spectrum into a primary continuum , neutral and ionized absorption , and a reflection component .
The photon index of the primary continuum has changed since 2005 ( \Gamma = 1.61 \substack { +0.02 \ -0.01 } \rightarrow 1.54 \pm { 0.02 } ) , while other components remain unchanged , indicative of minimal geometric changes to the central engine .
We constrain the high-energy cutoff of 3C 109 ( E _ { \text { cut } } = 49 \substack { +7 \ -5 } keV ) for the first time .
The reflector is found to be ionized ( log \xi = 2.3 \substack { +0.1 \ -0.2 } ) but no relativistic blurring is required by the data .
SED analysis confirms the super-Eddington nature of 3C 109 initially ( \lambda _ { Edd } > 2.09 ) .
However , we do not find any evidence for strong reflection ( R = 0.18 \substack { +0.04 \ -0.03 } ) or a steep power law index , as expected from a super-Eddington source .
This puts the existing virial mass estimate of 2 \times 10 ^ { 8 } M _ { \sun } into question .
We explore additional ways of estimating the Eddington ratio , some of which we find to be inconsistent with our initial SED estimate .
We obtain a new black hole mass estimate of 9.3 \times 10 ^ { 8 } M _ { \sun } , which brings all Eddington ratio estimates into agreement and does not require 3C 109 to be super-Eddington .