The nuclear disk in the E4 radio galaxy NGC 7052: evidence for a central black hole?
Abstract
NGC 7052 is an E4 radio galaxy with a LINER spectrum and a rapidly rotating 3.2" x 0.6" nuclear disk of dust and ionized gas. In ground-based data the Gaussian velocity dispersion of the emission lines falls from 250 km/s in the center to 60 km/s at 1.5". The rotation is 250 km/s at 1.5". The central peak in the velocity dispersion can be due either to seeing broadening of Keplerian rotation around a black hole of 10^9 solar masses, or alternatively, to turbulent gas motions near the center. We will obtain images of NGC 7052 with the WFPC2 and spectra with the FOS. The WFPC2 images serve as early acquisition data for the FOS observations. B {F450W} and I {F814W} wide-band images will be obtained with the nucleus positioned on the PC1 CCD. V {F547M} medium-band images will be obtained with the nucleus on the WF2 CCD. These images allow a determination of the optical depth of the dust, and of the stellar mass distribution near the nucleus. Narrow band images will be obtained with the LRF at 6480 Angstrom {`off-band'} and 6675 Angstrom {`on-band'}. This allows the construction of an H_alpha + [NII] image for studying the morphology of the nuclear gas disk. FOS/RD spectra will be obtained with the G570H grating and the 0.3 and 0.1-PAIR apertures, at five different positions, on the nucleus and along the major axis. These spectra allow a determination of the gas kinematics near the nucleus, yielding improved constraints on the presence or absence of a massive black hole.
- Publication:
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HST Proposal
- Pub Date:
- July 1995
- Bibcode:
- 1995hst..prop.5848V