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Date and Time of the Query: 2019-06-25 T20:43:23 PDT
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For refcode 2015MNRAS.450.3442L:
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NED Abstract

Copyright by Royal Astronomical Society. 2015MNRAS.450.3442L Comparison of simple mass estimators for slowly rotating elliptical galaxies Lyskova, N.; Thomas, J.; Churazov, E.; Tremaine, S.; Naab, T. Abstract. We compare the performance of mass estimators for elliptical galaxies that rely on the directly observable surface brightness and velocity dispersion profiles, without invoking computationally expensive detailed modelling. These methods recover the mass at a specific radius where the mass estimate is expected to be least sensitive to the anisotropy of stellar orbits. One uses the total luminosity-weighted velocity dispersion and evaluates the mass at a 3D half-light radius r_1/2_, i.e. it depends on the global galaxy properties. Another approach estimates the mass from the velocity dispersion at a radius R_2_ where the surface brightness declines as R^-2^, i.e. it depends on the local properties. We evaluate the accuracy of the two methods for analytical models, simulated galaxies and real elliptical galaxies that have already been modelled by the Schwarzschild's orbit-superposition technique. Both estimators recover an almost unbiased circular speed estimate with a modest rms scatter (<~10 per cent). Tests on analytical models and simulated galaxies indicate that the local estimator has a smaller rms scatter than the global one. We show by examination of simulated galaxies that the projected velocity dispersion at R_2_ could serve as a good proxy for the virial galaxy mass. For simulated galaxies the total halo mass scales with sigma_p_(R_2_) as M_vir [M_{{sun}_} h^{-1}] ~ 6x 10^{12}({{sigma_p(R_2)}over{200 km s^{-1}}})^4^ with rms scatter ~40 per cent. Key words: galaxies: Kinematics and Dynamics
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