H I Spectroscopy of Reverberation-mapped Active Galactic Nuclei

We present H I 21 cm spectroscopy from the Robert C. Byrd Green Bank Telescope for the host galaxies of 31 nearby active galactic nuclei with direct M _BH measurements from reverberation mapping. These are the first published H I detections for 12 galaxies, and the spectral quality is generally an improvement over archival data for the remainder of the sample. We present measurements of emission-line fluxes, velocity widths, and recessional velocities from which we derive H I mass, total gas mass, and redshifts. Combining M _GAS with constraints on M _STARS allows exploration of the baryonic content of these galaxies. We find a typical M _GAS /M _STARS fraction of 10%, with a few reaching ∼30%-50%. We also examine several relationships between M _STARS , M _GAS , M _BH , baryonic mass, and morphological type. We find a weak preference for galaxies with larger M _GAS to host more massive black holes. We also find gas-to-stellar fractions to weakly correlate with later types in unbarred spirals, with an approximately constant fraction for barred spirals. Consistent with previous studies, we find declining M _GAS /M _STARS with increasing M _STARS , with a slope suggesting the gas reservoirs have been replenished. Finally, we find a clear relationship for M _BH -M _BARY with a similar slope as M _BH -M _STARS reported by Bentz & Manne-Nicholas. The dwarf Seyfert NGC 4395 appears to follow this relationship as well, even though it has a significantly higher gas fraction and smaller M _BH than the remainder of our sample.