The e-TidalGCs Project: Modeling the extra-tidal features generated by Galactic globular clusters

TL;DR

The e-TidalGCs Project models and predicts the diverse extra-tidal features around all Galactic globular clusters with available 6D data, revealing complex morphologies and estimating the mass loss over the last 5 Gyr.

Contribution

This study provides the first comprehensive modeling of extra-tidal features for all relevant Galactic globular clusters, incorporating different Galactic potential models and comparing with observed stellar streams.

Findings

Variety of morphologies in extra-tidal features, from tails to halo-like structures.

Predicted mass loss of 0.3-2.1×10^7 solar masses over 5 Gyr.

Most lost mass is concentrated within 4-6 kpc of the Galactic center.

Abstract

We present the e-TidalGCs Project which aims at modeling and predicting the extra-tidal features surrounding all Galactic globular clusters for which 6D phase space information, masses and sizes are available (currently 159 globular clusters). We focus the analysis and presentation of the results on the distribution of extra-tidal material on the sky, and on the different structures found at different heliocentric distances. We emphasize the wide variety of morphologies found: beyond the canonical tidal tails, our models reveal that the extra-tidal features generated by globular clusters take a wide variety of shapes, from thin and elongated shapes, to thick, and complex halo-like structures. We also compare some of the most well studied stellar streams found around Galactic globular clusters to our model predictions, namely those associated to the clusters NGC 3201, NGC 4590, NGC 5466 and Pal 5. Additionally, we investigate how the distribution and extension in the sky of the simulated streams vary with the Galactic potential by making use of three different models, containing or not a central spheroid, or a stellar bar. Overall, our models predict that the mass lost by the current globular cluster population in the field from the last 5 Gyrs is between $0.3-2.1\times10^{7}M_{\odot}$, an amount comparable between 7-55 % of current mass. Most of this lost mass is found in the inner Galaxy, with the half-mass radius of this population being between 4-6 kpc. The outputs of the simulations will be publicly available, at a time when the ESA Gaia mission and complementary spectroscopic surveys are delivering exquisite data to which these models can be compared.