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Discrepancies between expected and observed rotation curves found in spiral galaxies are commonly interpreted as a proof for the existence of dark matter on galactic scale. In this work, the author employed theories of modified gravitation, instead of dark matter, to explain the phenomena of flat(no...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/17036 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Discrepancies between expected and observed rotation curves found in spiral galaxies are commonly interpreted as a proof for the existence of dark matter on galactic scale. In this work, the author employed theories of modified gravitation, instead of dark matter, to explain the phenomena of flat(non decreasing) rotation curves. Two modified gravitation are considered in this work, namely Modified Newtonian Dynamics (MOND) introduced by Milgrom <br />
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(1983) and Metric-Skew-Tensor-Gravity (MSTG) proposed by Moffat (2005). <br />
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Data of surface brightness and rotation curves of 19 galaxies has been examined, 17 of them are late type spirals and 2 are dwarf irregulars. In the frame <br />
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of MOND and MSTG the rotation curves were studied and tried to explain. MOND uses mass to luminosity ratio M=L of disk (and bulge, whenever it is not negligible) as free parameter(s), while MSTG uses Mass M and core radius rc. <br />
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The results of rotation curve fitting show that in general MOND and MSTG work equally good in explaining the rotation curves of galaxies under studied, without the need of exotic dark matter. On one hand, for galaxies with <br />
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negligible bulge contribution, MOND gives a more unique solution, because it works only with one free parameter, i.e. M/L of disk. On the other hand, MSTG is better in the sense of theoretical consideration, because it is based on <br />
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a covariant theory, whereas MOND, in its original version, can be considered as an ad hoc solution based on phenomenology and lack of a well motivated theory. |
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