IAS Gyan

Daily News Analysis

Researchers use AI to create the Milky Way’s family tree

27th November, 2020 Science and Technology

Context: Artificial intelligence (AI) has helped in creating the first complete family tree of Earth’s home galaxy – the Milky Way.

Fig: From left to right, the identified ancestor galaxies: Sagittarius, Sequoia, Kraken, the Milky Way’s main originator, Helmi streams, and Gaia-Enceladus-Sausage.  

  • The researchers used AI to analyse large groups of stars with as many as million stars, orbiting the Milky Way.
  • The Milky Way hosts over 150 such clusters, many of which formed in the smaller galaxies that merged to form the galaxy
  • With the help of the latest models and observations, the researchers use the clusters as “fossils” to generate the history of galaxies.
  • The main challenge of connecting the properties of globular clusters [large group of stars] to the merger history of their host galaxy has always been that galaxy assembly is an extremely messy process, during which the orbits of the globular clusters are completely reshuffled.

Digitising ancient maps using AI

  • To simplify the complex system, the team developed advanced computer simulations called E-MOSAICS to capture the formation of Milky Way-like galaxies, and then used this knowledge on specific groups of globular clusters in the Milky Way.
  • By applying AI on these groups of globular clusters, the researchers were able to predict the merger times of the Milky Way’s ancestor galaxies with high precision.
  • The process also revealed a previously unknown collision between the Milky Way and an enigmatic galaxy, which the researchers named ‘Kraken’.
  • The merger with Kraken took place 11 billion years ago, when the Milky Way was four times less massive.
  • The collision with Kraken must have been the most significant merger the Milky Way ever experienced.
  • Over the course of its history, the Milky Way cannibalised about five galaxies with more than 100 million stars, and about fifteen with at least 10 million stars.