期刊
ASTROPHYSICAL JOURNAL
卷 718, 期 1, 页码 380-391出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/718/1/380
关键词
galaxies: dwarf; galaxies: kinematics and dynamics
资金
- JHU/STScI Davis Fellowship
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [0908370] Funding Source: National Science Foundation
Dwarf and low surface brightness (LSB) galaxies are ideal objects to test modified Newtonian dynamics (MOND), because in most of these galaxies the accelerations fall below the threshold where MOND supposedly applies. We have selected from the literature a sample of 27 dwarf and LSB galaxies. MOND is successful in explaining the general shape of the observed rotation curves for roughly three quarters of the galaxies in the sample presented here. However, for the remaining quarter, MOND does not adequately explain the observed rotation curves. Considering the uncertainties in distances and inclinations for the galaxies in our sample, a small fraction of poor MOND predictions is expected and is not necessarily a problem for MOND. We have also made fits taking the MOND acceleration constant, a(0), as a free parameter in order to identify any systematic trends. We find that there appears to be a correlation between central surface brightness and the best-fit value of a(0), in the sense that lower surface brightness galaxies tend to have lower a(0). However, this correlation depends strongly on a small number of galaxies whose rotation curves might be uncertain due to either bars or warps. Without these galaxies, there is less evidence of a trend, but the average value we find for a(0) approximate to 0.7 x 10(-8) cm s(-2) is somewhat lower than derived from previous studies. Such lower fitted values of a(0) could occur if external gravitational fields are important.
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