Vertical dynamics of disc galaxies in modified Newtonian dynamics |
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| Authors: | Carlo Nipoti Pasquale Londrillo Hong Sheng Zhao Luca Ciotti |
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| Institution: | Astronomy Department, University of Bologna, via Ranzani 1, 40127 Bologna, Italy;INAF-Bologna Astronomical Observatory, I-40127 Bologna, Italy;Scottish Universities Physics Alliance (SUPA), University of St Andrews, St Andrews, Fife KY16 9SS |
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| Abstract: | We investigate the possibility of discriminating between modified Newtonian dynamics (MOND) and Newtonian gravity with dark matter, by studying the vertical dynamics of disc galaxies. We consider models with the same circular velocity in the equatorial plane (purely baryonic discs in MOND and the same discs in Newtonian gravity embedded in spherical dark matter haloes), and we construct their intrinsic and projected kinematical fields by solving the Jeans equations under the assumption of a two-integral distribution function. We find that the vertical velocity dispersion of deep MOND discs can be much larger than in the equivalent spherical Newtonian models. However, in the more realistic case of high surface density discs, this effect is significantly reduced, casting doubt on the possibility of discriminating between MOND and Newtonian gravity with dark matter by using current observations. |
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| Keywords: | gravitation stellar dynamics galaxies: kinematics and dynamics |
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