Our galaxy cannibalized 20 other galaxies filled with millions of stars

Our galaxy cannibalized 20 other galaxies filled with millions of stars

Our galaxy, the Milky Way, cannibalized about five galaxies with more than 100 million stars and about fifteen with at least 10 million stars, according to the first complete family tree of our galaxy .

This genealogical tree has been developed by a group of astrophysicists who have analyzed the properties of globular clusters that orbit the Milky Way using artificial intelligence. The work is published in Monthly Notices of the Royal Astronomical Society .

Neural Network

The study was conducted by developing a set of advanced computer simulations of the formation of Milky Way-like galaxies. Their simulations, called E-MOSAICS , are unique in that they include a complete model for the formation, evolution, and destruction of globular clusters.

Family tree

In this way, the researchers were able to relate the ages, chemical compositions and orbital movements of globular clusters with the properties of the progenitor galaxies in which they formed,

According to this simulation, the Milky Way is home to more than 150 globular clusters, many of which formed in the smallest galaxies that merged to form the galaxy we live in today. The most massive progenitor galaxies collided with the Milky Way between 6 and 11 billion years ago .

As Diederik Kruijssen m from the University of Heidelberg Astronomy Center explains:

To make sense of the complex system that remains today, we decided to use artificial intelligence. We trained an artificial neural network in the E-MOSAICS simulations to relate the properties of the globular cluster to the fusion history of the host galaxy. We tested the algorithm tens of thousands of times in simulations and were amazed at how accurately it was able to reconstruct the fusion histories of the simulated galaxies, using only their globular cluster populations.