The escape of globular clusters from the satellite dwarf galaxies of the Milky Way

Abstract

Using numerical simulations, we have studied the escape of globular clusters (GCs) from the satellite dwarf spheroidal galaxies (dSphs) of the Milky Way (MW). We start by following the orbits of a large sample of GCs around dSphs in the presence of the MW potential field. We then obtain the fraction of GCs leaving their host dSphs within a Hubble Time. We model dSphs by a Hernquist density profile with masses between 107 M⊙ and 7 × 109 M⊙. All dSphs lie on the Galactic disc plane, but they have different orbital eccentricities and apogalactic distances. We compute the escape fraction of GCs from 13 of the most massive dSphs of the MW, using their realistic orbits around the MW (as determined by Gaia). The escape fraction of GCs from 13 dSphs is in the range $12{{\ \rm per\ cent}}$ to $93{{\ \rm per\ cent}}$. The average escape time of GCs from these dSphs was less than 8 Gyrs, indicating that the escape process of GCs from dSphs was over. We then adopt a set of observationally-constrained density profiles for specific case of the Fornax dSph. According to our results, the escape fraction of GCs shows a negative correlation with both the mass and the apogalactic distance of the dSphs, as well as a positive correlation with the orbital eccentricity of dSphs. In particular, we find that the escape fraction of GCs from the Fornax dSph is between $13{{\ \rm per\ cent}}$ and $38{{\ \rm per\ cent}}$. Finally, we observe that when GCs leave their host dSphs, their final orbit around the MW does not differ much from their host dSphs.

The Origin of the Large Magellanic Cloud Globular Cluster NGC 2005

“…Shao et al (2021) showed that accreted globular clusters in the Milky Way and Fornax are less centrally concentrated than those formed in situ. Moreover, globular clusters that escape dwarf satellites of the Milky Way are found orbiting the latter (Rostami Shirazi et al 2022). Piatti et al (2019) derived mean proper motions of the 15 LMC globular clusters, and from existent radial velocities, they computed their velocity vectors.…”

Peeking beneath the precision floor -- II. Probing the chemo-dynamical histories of the potential globular cluster siblings, NGC 288 and NGC 362

“…Belokurov et al 2018;Haywood et al 2018;Helmi et al 2018;Myeong et al 2019;Massari et al 2019;Kruijssen et al 2019;Forbes 2020;Horta et al 2021;Koppelman et al 2019;Naidu et al 2020). Along with the dGals themselves, each of these merger events is likely to have brought in a system of associated globular clusters (GCs) (Searle & Zinn 1978;Mackey & Gilmore 2004;Abadi et al 2006;Law & Majewski 2010;Trujillo-Gomez et al 2021;Rostami Shirazi et al 2022). And while these accreted ★ E-mail: sm2744@cam.ac.uk dGals have long since been disrupted, distributing their constituent stars across the MW, some members of their GC systems have likely remained intact.…”