The imprint of the MOND external field effect on the Oort cloud comets aphelia distribution

Understand

Milgromian dynamics (MD or MOND) is a promising physical description excelling especially in galaxies.

• When formulated as a modified gravity theory, it leads to the so called external field effect (EFE).
• In the case of the solar system this means that bodies orbiting the Sun are influenced, beyond its tidal effect, by the external gravitational field of the Galaxy with magnitude $\sim2\times10^{-10}$ m s$^{-2}$ and time-varying direction.
• Aphelia of intermediate outer Oort cloud (OC) comets ($30<X<60,~X\equiv 10^{6}/a[\text{au}]$, where $a$ is semimajor axis) are distributed non-uniformly on the celestial sphere, showing an apparent concentration around a great circle centered at Galactic longitudes $L=-45$ and 135 deg.