Program: GS-2005A-Q-38

Title:Stellar dynamics measurement of the mass of the black hole in CentaurusA
PI:Niranjan Thatte
Co-I(s): Roger L. Davies, Davor Krajnovic, Robert Sharp, Matthias Tecza

Abstract

Our CIRPASS near infrared integral field spectroscopic observations of the gas kinematics in the nuclear region of Centaurus A show very complex gas motions, casting doubt on the Keplerian rotating disk interpretation presented by Marconi et al. (2001), based on long slit VLT spectra. We reproduce the morphology observed by Schreier et al. (1998) with HST/NICMOS in hydrogen recombination lines. However, the observed kinematics point to a larger rotating/outflowing structure, in addition to the compact disk proposed by Marconi et al. In general, the use of gas kinematics to derive a central black hole mass in galaxies with an active nucleus is fraught with perils, as is well demonstrated by Verdoes-Kleijn et al. (2003) for NGC 4335. We propose to settle the debate through a definitive mass measurement of the nuclear black hole in Centaurus A, the nearest radio galaxy, using stellar dynamics techniques and observations with the GNIRS IFU. The proposed K band observations can penetrate the significant extinction toward the nucleus, and yield 2D maps of the stellar velocity field, truly mapping the gravitational potential in the nuclear region.

Publications using this program's data