Velocity mapping and models of the elliptical galaxies NGC 720, NGC 1052, and NGC 4697

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Abstract
Extensive long-slit spectroscopic observations of the E3-E4 elliptical galaxies NGC 720, 1052, and 4697 are presented, including results from slits that are parallel to the major and minor axes but which do not pass through the nucleus. A novel deprojection algorithm is used to construct axisymmetric mass models of these systems from CCD surface photometry. These mass models are combined with the Jeans equations to yield predicted fields of line-of-sight velocity dispersion and streaming velocity. Comparison of these fields with the observed velocities imply: (i) none of these systems can have isotropic velocity dispersion tensors; (ii) diminishing the assumed inclination i of any given galaxy tends to decrease the line-of-sight velocity dispersion and counterintuitively, to increase the line-of-sight rotation speeds; (iii) the ratio of the line-of-sight velocity dispersion along the minor axis to that along the major axis is a sensitive diagnostic of the importance of a third integral for a galaxy's structure; (iv) our observations of NGC 1052 can be successfully modeled with a dis3 tribution function of the form f(E, Lz) but our observations of NGC 720 and NGC 4697 cannot; (v) in NGC 4697 the observed rotation speeds tend to decline away from the major axis faster than the models predict; and (vi) the data are consistent with constant mass-to-light ratio through the studied portions of all three systems

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