• We have undertaken a new ground-based monitoring campaign on the broad-line radio galaxy 3C390.3 to improve the measurement of the size of the broad emission-line region and to estimate the black hole mass. Optical spectra and g-band images were observed in late 2005 for three months using the 2.4m telescope at MDM Observatory. Integrated emission-line flux variations were measured for the hydrogen Balmer lines H, H, H, and for the helium line He II4686, as well as g-band fluxes and the optical active galactic nucleus (AGN) continuum at =5100 . The g-band fluxes and the optical AGN continuum vary simultaneously within the uncertainties, cent = (0.2 1.1)days. We find that the emission-line variations are delayed with respect to the variable g-band continuum by (H) = 56.3+2.4-6.6days, (H) = 44.3+3.0-3.3days, (H) = 58.1 +4.3-6.1days, and (He II4686) = 22.3 +6.5-3.8days. The blue and red peaks in the double-peaked line profiles, as well as the blue and red outer profile wings, vary simultaneously within 3 days. This provides strong support for gravitationally bound orbital motion of the dominant part of the line-emitting gas. Combining the time delay of the strong Balmer emission lines of H and H and the separation of the blue and red peaks in the broad double-peaked profiles in their rms spectra, we determine Mvirbh = 1.77+0.29-0.31 108 M and using line of the rms spectra M virbh = 2.60+0.23-0.31 108 M for the central black hole of 3C390.3, respectively. Using the inclination angle of the line-emitting region which is measured from superluminal motion detected in the radio range, accretion disk models to fit the optical double-peaked emission-line profiles, and X-ray observations, the mass of the black hole amounts to Mbh = 0.86 +0.19-0.18 109 M (peak separation) and Mbh = 1.26+0.21-0.16 109 M (line), respectively. This result is consistent with the black hole masses indicated by simple accretion disk models to describe the observed double-peaked profiles, derived from the stellar dynamics of 3C390.3, and with the AGN radius-luminosity relation. Thus, 3C390.3 as a radio-loud AGN with a low Eddington ratio, L edd/L bol = 0.02, follows the same AGN radius-luminosity relation as radio-quiet AGNs. 2012. The American Astronomical Society. All rights reserved.

published proceedings


author list (cited authors)

  • Dietrich, M., Peterson, B. M., Grier, C. J., Bentz, M. C., Eastman, J., Frank, S., ... Prieto, J. L.

citation count

  • 48

complete list of authors

  • Dietrich, Matthias||Peterson, Bradley M||Grier, Catherine J||Bentz, Misty C||Eastman, Jason||Frank, Stephan||Gonzalez, Raymond||Marshall, Jennifer L||DePoy, Darren L||Prieto, Jose L

publication date

  • September 2012