The mass of the black hole in RE J1034+396

Context. The black hole mass measurement in active galaxies is a challenge, particularly in sources where the reverberation method cannot be applied.
Aims: We aim to determine the black hole mass in a very special object, RE J1034+396, one of the two active galactic nuclei (AGN) with quasi-periodic oscillations detected in X-rays, and a single bright AGN with optical band totally dominated by starlight.
Methods: We fit the stellar content using the code starlight, and the broad band disk contribution to optical/UV/X-ray emission is modeled with OPTXAGNF. Based on starlight, we develop our own code OPTGAL for simultaneous fitting of the stellar, Fe II, and BC content in the optical/UV/X-ray data. We also determine the black hole mass using several other independent methods.
Results: Various methods give contradictory results. Most measurements of the black hole mass are in the range 10⁶-10⁷ M_⊙, and the measurements based on dynamics give higher values than measurements based on Hβ and Mg II emission lines.