The radial acceleration relation and a magnetostatic analogy in quasilinear MOND
Recently a remarkable relation has been demonstrated between the observed radial acceleration in disk galaxies and the acceleration predicted on the basis of baryonic matter alone. Here we study this relation within the framework of the modified gravity model MOND. The field equations of MOND automa...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2018-01-01
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| Series: | New Journal of Physics |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1367-2630/aaca23 |
| _version_ | 1797750718592974848 |
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| author | Katherine Brown Roshan Abraham Leo Kell Harsh Mathur |
| author_facet | Katherine Brown Roshan Abraham Leo Kell Harsh Mathur |
| author_sort | Katherine Brown |
| collection | DOAJ |
| description | Recently a remarkable relation has been demonstrated between the observed radial acceleration in disk galaxies and the acceleration predicted on the basis of baryonic matter alone. Here we study this relation within the framework of the modified gravity model MOND. The field equations of MOND automatically imply the radial acceleration relation (RAR) for spherically symmetric galaxies, but for disk galaxies deviations from the relation are expected. Here we investigate whether these deviations are of sufficient magnitude to bring MOND into conflict with the observed relation. In the quasilinear formulation of MOND, to calculate the gravitational field of a given distribution of matter, an intermediate step is to calculate the ‘pristine field’, which is a simple nonlinear function of the Newtonian field corresponding to the same distribution of matter. Hence, to the extent that the quasilinear gravitational field is approximately equal to the pristine field, the RAR will be satisfied. We show that the difference between the quasilinear and pristine fields obeys the equations of magnetostatics; the curl of the pristine field serves as the source for the difference in the two fields, much as currents serve as sources for the magnetic field. Using the magnetostatic analogy we numerically study the difference between the pristine and quasilinear fields for simple model galaxies with a Gaussian profile. Our principal finding is that the difference between the fields is small compared to the observational uncertainties and that quasilinear MOND is therefore compatible with the observed RAR. |
| first_indexed | 2024-03-12T16:36:56Z |
| format | Article |
| id | doaj.art-dd6dfd4d310c4790bf9e6afee3372944 |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:36:56Z |
| publishDate | 2018-01-01 |
| publisher | IOP Publishing |
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| series | New Journal of Physics |
| spelling | doaj.art-dd6dfd4d310c4790bf9e6afee33729442023-08-08T14:51:33ZengIOP PublishingNew Journal of Physics1367-26302018-01-0120606304210.1088/1367-2630/aaca23The radial acceleration relation and a magnetostatic analogy in quasilinear MONDKatherine Brown0https://orcid.org/0000-0002-1567-5620Roshan Abraham1Leo Kell2Harsh Mathur3https://orcid.org/0000-0003-4451-8963Department of Physics, Hamilton College, Clinton, NY 13323, United States of AmericaDepartment of Physics, Case Western Reserve University , Cleveland, Ohio 44106-7079, United States of AmericaDepartment of Physics, Hamilton College, Clinton, NY 13323, United States of AmericaDepartment of Physics, Case Western Reserve University , Cleveland, Ohio 44106-7079, United States of AmericaRecently a remarkable relation has been demonstrated between the observed radial acceleration in disk galaxies and the acceleration predicted on the basis of baryonic matter alone. Here we study this relation within the framework of the modified gravity model MOND. The field equations of MOND automatically imply the radial acceleration relation (RAR) for spherically symmetric galaxies, but for disk galaxies deviations from the relation are expected. Here we investigate whether these deviations are of sufficient magnitude to bring MOND into conflict with the observed relation. In the quasilinear formulation of MOND, to calculate the gravitational field of a given distribution of matter, an intermediate step is to calculate the ‘pristine field’, which is a simple nonlinear function of the Newtonian field corresponding to the same distribution of matter. Hence, to the extent that the quasilinear gravitational field is approximately equal to the pristine field, the RAR will be satisfied. We show that the difference between the quasilinear and pristine fields obeys the equations of magnetostatics; the curl of the pristine field serves as the source for the difference in the two fields, much as currents serve as sources for the magnetic field. Using the magnetostatic analogy we numerically study the difference between the pristine and quasilinear fields for simple model galaxies with a Gaussian profile. Our principal finding is that the difference between the fields is small compared to the observational uncertainties and that quasilinear MOND is therefore compatible with the observed RAR.https://doi.org/10.1088/1367-2630/aaca23alternative theories of gravitymodified Newtonian dynamics (MOND)radial acceleration relationgalactic astrophysics |
| spellingShingle | Katherine Brown Roshan Abraham Leo Kell Harsh Mathur The radial acceleration relation and a magnetostatic analogy in quasilinear MOND New Journal of Physics alternative theories of gravity modified Newtonian dynamics (MOND) radial acceleration relation galactic astrophysics |
| title | The radial acceleration relation and a magnetostatic analogy in quasilinear MOND |
| title_full | The radial acceleration relation and a magnetostatic analogy in quasilinear MOND |
| title_fullStr | The radial acceleration relation and a magnetostatic analogy in quasilinear MOND |
| title_full_unstemmed | The radial acceleration relation and a magnetostatic analogy in quasilinear MOND |
| title_short | The radial acceleration relation and a magnetostatic analogy in quasilinear MOND |
| title_sort | radial acceleration relation and a magnetostatic analogy in quasilinear mond |
| topic | alternative theories of gravity modified Newtonian dynamics (MOND) radial acceleration relation galactic astrophysics |
| url | https://doi.org/10.1088/1367-2630/aaca23 |
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