Study of the Influence of an Evolving Galactic Potential on the Orbital Properties of 152 Globular clusters with Data from the Gaia EDR3 Catalogue

TL;DR

This study investigates how the evolving gravitational potential of the Milky Way affects the orbital properties of 152 globular clusters, using Gaia EDR3 data and a semi-cosmological model to compare static and dynamic potential effects.

Contribution

It is the first to analyze separately the impacts of changing masses and sizes of Galactic components on globular cluster orbits over billions of years.

Findings

Distant globular clusters experience the most significant orbital changes.

Changes in masses and sizes of Galactic components act oppositely on orbits.

Galactic potential can be considered static over 5 Gyr within data uncertainties.

Abstract

We have studied the influence of an evolving gravitational potential of the Milky Way Galaxy on the orbital motion of 152 globular clusters with proper motions from the Gaia EDR3 catalogue and mean distances from Baumgardt and Vasiliev (2021). To construct a semicosmological evolving model potential with changing masses and sizes of the Galactic components, we have used the algorithm described in Haghi et al. (2015). The adopted axisymmetric three-component model potential of the Galaxy includes a spherical bulge, a flat Miyamoto--Nagai disk, and a spherical Navarro--Frenk--White dark matter halo.The orbits are integrated backward in time. We compare the orbital parameters of globular clusters derived in static and evolving potentials when integrating the orbits for 5 and 12 Gyr backward. For the first time we have studied the influence of separately a change in the masses and a change in the sizes of the Galactic components. The changes in the masses and sizes of the components are shown to act on the orbital parameters in the opposite way. At small Galactocentric distances this influence is maximally compensated for. The orbits of distant globular clusters and those with a large apocenter distance undergo the biggest changes. We show that on time scales up to $-5$~Gyr the orbits of globular clusters in the case of a potential with both changing masses and changing sizes of the components undergo, on average, minor changes compared to the case of a static potential. These changes fit into the limits of the statistical uncertainties caused by the errors in the data. So, on these time scales the Galactic potential may be deemed static. We provide tables with the orbital parameters of globular clusters derived in both static and evolving potentials.