Is there a fundamental acceleration scale in galaxies?. (arXiv:1812.05002v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Chang_Z/0/1/0/all/0/1">Zhe Chang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhou_Y/0/1/0/all/0/1">Yong Zhou</a>
Milgrom’s modified Newtonian dynamics (MOND) can explain well the mass
discrepancy problem in galaxy without invoking dark matter. The MOND theory
predicts a universal constant acceleration scale in galaxy, below which the
Newtonian dynamics is no longer valid. Recently, Rodrigues et al. (2018b)
analyzed 193 high-quality disk galaxies by using Bayesian inference and they
concluded that the probability of existence of a fundamental acceleration scale
is essentially 0. In this paper, we use the same method to revisit the same
question: Is there a fundamental acceleration scale in galaxies? We fit each
galaxy rotation curve of 175 SPARC galaxies with almost the same Gaussian prior
as used in Li et al. (2018) and a variable acceleration scale. After
marginalizing over the nuisance parameters, we find that the marginalized
posterior distribution of the acceleration scale become broader than that from
a flat prior. The incompatibility between the global best fit and the
marginalized posterior distribution of the acceleration scale is greatly
reduced. However, there still exist evidence that rejects MOND as a fundamental
theory. More accurate observations are needed to exclude or confirm the
existence of a fundamental acceleration scale in galaxies.
Milgrom’s modified Newtonian dynamics (MOND) can explain well the mass
discrepancy problem in galaxy without invoking dark matter. The MOND theory
predicts a universal constant acceleration scale in galaxy, below which the
Newtonian dynamics is no longer valid. Recently, Rodrigues et al. (2018b)
analyzed 193 high-quality disk galaxies by using Bayesian inference and they
concluded that the probability of existence of a fundamental acceleration scale
is essentially 0. In this paper, we use the same method to revisit the same
question: Is there a fundamental acceleration scale in galaxies? We fit each
galaxy rotation curve of 175 SPARC galaxies with almost the same Gaussian prior
as used in Li et al. (2018) and a variable acceleration scale. After
marginalizing over the nuisance parameters, we find that the marginalized
posterior distribution of the acceleration scale become broader than that from
a flat prior. The incompatibility between the global best fit and the
marginalized posterior distribution of the acceleration scale is greatly
reduced. However, there still exist evidence that rejects MOND as a fundamental
theory. More accurate observations are needed to exclude or confirm the
existence of a fundamental acceleration scale in galaxies.
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