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H. D. Tran, H. Ford, Z. Tsvetanov, J. Davies (JHU), W. Jaffe (Univ. of Leiden)
We present early results from a WFPC2 survey of early type galaxies aimed at searching for small (r ~ few hundred pc) nuclear dusty disks. In order to examine the influence of the host environment on the detection of such disks, two volume-limited samples are studied. One examines an IRAS-selected archival sample of all early-type galaxies at v < 3000 km/s with 3\sigma or greater detection at 100\mum, and the other surveys, in WFPC2 snapshot mode, a large selection of early-type galaxies with v < 3400 km/s, and b > 20\deg~regardless of IRAS properties. Our analysis shows that 16% of the 67 non-IRAS selected galaxies harbour nuclear dusty disks, while 38% of the 42 IRAS selected galaxies do.
We discuss the role played by galaxy environment in determining the frequency of dusty disk, and investigate the connection between the presence and morphology of the disks and the type and level of nuclear activity. The galaxies found to harbor nuclear disks in our survey will make up an important database for future studies aiming at deriving the central black hole masses, through the use of gas dynamics, and examining their demography.