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Date and Time of the Query: 2019-08-22 T05:40:19 PDT
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For refcode 1990ApJ...361...78B:
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Copyright by American Astronomical Society. Reproduced by permission
1990ApJ...361...78B VELOCITY MAPPING AND MODELS OF THE ELLIPTICAL GALAXIES NGC 720, NGC 1052, AND NGC 4697 J. J. BINNEY Steward Observatory and Department of Theoretical Physics, Oxford University ROGER L. DAVIES National Optical Astronomical Observatories and Department of Astrophysics, Oxford University AND GARTH D. ILLINGWORTH University of California Observatories/Lick Observatory and the Board of Studies in Astronomy and Astrophysics, University of California, Santa Cruz Received 1989 March 15; accepted 1990 March 20 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 distribution function of the form f(E, L_z_) 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. Subject headings: galaxies: formation - galaxies: individual (NGC 720, 1052, 4697) - galaxies: internal motions - galaxies: structure
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