Understanding the Future of the Milky Way and Andromeda

Introduction

• The potential collision and merger of the Milky Way and the Andromeda galaxy initiated a personal interest in astrophysics.
• The light from Andromeda is Doppler shifted, indicating its movement towards the Milky Way at 301 km/s.
• Recent studies suggest only a 50% chance that a merger will occur in the next 10 billion years due to the influence of nearby galaxies.

Key Galactic Players

• Milky Way: Contains over 100 billion stars, spans 90,000 light-years, with multiple dwarf galaxies orbiting it.
• Andromeda Galaxy (M31): The largest in the local group, it spans 150,000 light-years and contains around a trillion stars.
• Triangulum Galaxy (M33): Approximately 60,000 light-years wide with 40 billion stars.
• Large and Small Magellanic Clouds: Significant dwarf galaxies in the Milky Way's gravitational influence.

Galactic Dynamics

• The local group consists of gravitationally bound galaxies whose movements are more influenced by mutual gravitational forces than the universe's expansion.
• The interactions between the Milky Way, Andromeda, and nearby dwarf galaxies create a complex n-body problem (e.g., 80-body), rather than a simple two-body scenario.

Simulation Insights

• Simulations require precise data on galaxy mass, position, and velocity, improved by observations from the Hubble Space Telescope and the Gaia mission.
• Sabala and collaborators focused on simulations involving Andromeda, the Milky Way, M33, and the Large Magellanic Cloud.
• Variations in initial parameters lead to different outcomes in simulated mergers.

Impact of Neighboring Galaxies

• Including M33 and the Large Magellanic Cloud in simulations affects the chances of a Milky Way-Andromeda merger.
  • M33 increases the likelihood to 63% due to its gravitational slowdown effect on Andromeda.
  • Large Magellanic Cloud decreases the likelihood to 37% as it speeds up the Milky Way relative to Andromeda.
• Both galaxies will eventually merge with their larger neighbors according to the simulations.

Conclusion and Future Research

• Current uncertainties in data make definite predictions about the Milky Way-Andromeda merger impossible.
• Ongoing and future missions, such as the advancing Gaia data and observations from the James Webb Space Telescope, aim to reduce these uncertainties and provide clearer insights.
• The notion of a certain impending galaxy merger remains speculative, highlighting the need for more detailed research and data.

Sponsorship Note

• The video content was sponsored by SLY, an eSIM provider offering global connectivity advantages over traditional physical SIM cards. Use code Dr. Becky for a discount on data plans on s.com/dbecky.