Constraining the MOdified Newtonian Dynamics from spherically symmetrical hydrodynamic accretion

TL;DR

This paper examines the consistency of MOND through spherically symmetric hydrodynamic accretion, finding that it supports a modification of the law of dynamics rather than gravity, with implications for astrophysics.

Contribution

It provides a critical analysis of MOND in hydrodynamic accretion, constraining its physical interpretation and showing the modified dynamics approach yields real solutions.

Findings

Real solutions exist if MOND modifies the law of dynamics.

No real solutions if MOND modifies gravity as an acceleration scale.

Mass accretion rate changes by up to ~15% under MOND modifications.

Abstract

The MOdified Newtonian Dynamics (MOND) is an alternative to the dark matter assumption that can explain the observed flat rotation curve of galaxies. Here hydrodynamic accretion is considered to critically check the consistency and to constrain the physical interpretation of this theory. It is found that, in case of spherically symmetrical hydrodynamic accretion, the modified Euler's equation has real solution if the interpretation is assumed to be a modification of the law of dynamics. There is no real solution if it is assumed to be an acceleration scale dependent modification of the gravitational law. With the modified Euler's equation, the steady state mass accretion rate is found to change up to ~ 15%. The astrophysical and cosmological implications of these results are also discussed.