2012ApJ...756..179M

We present stellar kinematics and orbit superposition models for the central regions of four brightest cluster galaxies, based upon integral-field spectroscopy at Gemini, Keck, and McDonald Observatories. Our integral-field data span radii from <100 pc to tens of kiloparsecs, comparable to the effective radius of each galaxy. We report black hole masses, M_•, of 2.1^+1.6 _–1.6x10¹⁰ M_☉for NGC 4889, 9.7^+3.0_–2.5x 10⁹ M_☉ for NGC 3842, and 1.3^+0.5_–0.4x10⁹ M_☉for NGC 7768, with errors representing 68% confidence limits. For NGC 2832, we report an upper limit of M_•< 9.0x10⁹ M_☉. Our models of each galaxy include a dark matter halo, and we have tested the dependence of M_• on the model dark matter profile. Stellar orbits near the center of each galaxy are tangentially biased, on comparable spatial scales to the galaxies' photometric cores. We find possible photometric and kinematic evidence for an eccentric torus of stars in NGC 4889, with a radius of nearly 1 kpc. We compare our measurements of M_• to the predicted black hole masses from various fits to the relations between M_• and stellar velocity dispersion (σ), luminosity (L), or stellar mass (M_{sstarf}). Still, the black holes in NGC 4889 and NGC 3842 are significantly more massive than all σ-based predictions and most L-based predictions. The black hole in NGC 7768 is consistent with a broader range of predictions.