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Polar ring galaxies as tests of gravity

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Abstract
Polar ring galaxies are ideal objects with which to study the three-dimensional shapes of galactic gravitational potentials since two rotation curves can be measured in two perpendicular planes. Observational studies have uncovered systematically larger rotation velocities in the extended polar rings than in the associated host galaxies. In the dark matter context, this can only be explained through dark haloes that are systematically flattened along the polar rings. Here, we point out that these objects can also be used as very effective tests of gravity theories, such as those based on Milgromian dynamics (also known as Modified Newtonian Dynamics or MOND). We run a set of polar ring models using both Milgromian and Newtonian dynamics to predict the expected shapes of the rotation curves in both planes, varying the total mass of the system, the mass of the ring with respect to the host and the size of the hole at the centre of the ring. We find that Milgromian dynamics not only naturally leads to rotation velocities being typically higher in the extended polar rings than in the hosts, as would be the case in Newtonian dynamics without dark matter, but that it also gets the shape and amplitude of velocities correct. Milgromian dynamics thus adequately explains this particular property of polar ring galaxies.
Keywords
galaxies: general, gravitation, galaxies: individual: NGC 4650A, galaxies: kinematics and dynamics, dark matter, MODIFIED NEWTONIAN DYNAMICS, DARK-MATTER, NGC 4650A, DISK GALAXIES, HALO, MOND, MASS, KINEMATICS, COSMOLOGY, EVOLUTION

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Citation

Please use this url to cite or link to this publication:

Chicago
Lüghausen, F, B Famaey, P Kroupa, G Angus, F Combes, Gianfranco Gentile, O Tiret, and H Zhao. 2013. “Polar Ring Galaxies as Tests of Gravity.” Monthly Notices of the Royal Astronomical Society 432 (4): 2846–2853.
APA
Lüghausen, F., Famaey, B., Kroupa, P., Angus, G., Combes, F., Gentile, G., Tiret, O., et al. (2013). Polar ring galaxies as tests of gravity. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 432(4), 2846–2853.
Vancouver
1.
Lüghausen F, Famaey B, Kroupa P, Angus G, Combes F, Gentile G, et al. Polar ring galaxies as tests of gravity. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. 2013;432(4):2846–53.
MLA
Lüghausen, F, B Famaey, P Kroupa, et al. “Polar Ring Galaxies as Tests of Gravity.” MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 432.4 (2013): 2846–2853. Print.
@article{4092269,
  abstract     = {Polar ring galaxies are ideal objects with which to study the three-dimensional shapes of galactic gravitational potentials since two rotation curves can be measured in two perpendicular planes. Observational studies have uncovered systematically larger rotation velocities in the extended polar rings than in the associated host galaxies. In the dark matter context, this can only be explained through dark haloes that are systematically flattened along the polar rings. Here, we point out that these objects can also be used as very effective tests of gravity theories, such as those based on Milgromian dynamics (also known as Modified Newtonian Dynamics or MOND). We run a set of polar ring models using both Milgromian and Newtonian dynamics to predict the expected shapes of the rotation curves in both planes, varying the total mass of the system, the mass of the ring with respect to the host and the size of the hole at the centre of the ring. We find that Milgromian dynamics not only naturally leads to rotation velocities being typically higher in the extended polar rings than in the hosts, as would be the case in Newtonian dynamics without dark matter, but that it also gets the shape and amplitude of velocities correct. Milgromian dynamics thus adequately explains this particular property of polar ring galaxies.},
  author       = {L{\"u}ghausen, F and Famaey, B and Kroupa, P and Angus, G and Combes, F and Gentile, Gianfranco and Tiret, O and Zhao, H},
  issn         = {0035-8711},
  journal      = {MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY},
  keyword      = {galaxies: general,gravitation,galaxies: individual: NGC 4650A,galaxies: kinematics and dynamics,dark matter,MODIFIED NEWTONIAN DYNAMICS,DARK-MATTER,NGC 4650A,DISK GALAXIES,HALO,MOND,MASS,KINEMATICS,COSMOLOGY,EVOLUTION},
  language     = {eng},
  number       = {4},
  pages        = {2846--2853},
  title        = {Polar ring galaxies as tests of gravity},
  url          = {http://dx.doi.org/10.1093/mnras/stt639},
  volume       = {432},
  year         = {2013},
}

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