Scientists use ‘Space Archaeology’ to rebuild hidden history of giant spiral galaxy

A team of astronomers from the Center for Astrophysics | Harvard & Smithsonian has pioneered a new field called "extragalactic archaeology."

According to the new study published in the journal Nature Astronomy, the scientists found a way to reconstruct the evolution and timeline of distant galaxies. Previously “extragalactic archaeology” method was used for only the Milky Way Galaxy.

By studying the chemical "fingerprints", specifically oxygen patterns, in the distant spiral galaxy NGC 1365, researchers were able to reconstruct its 12-billion-year history.

"This is the first time that a chemical archaeology method has been used with such fine detail outside our own galaxy," says Lisa Kewley, lead author, Harvard professor, and director of the Center for Astrophysics.

By comparing real-world observations from the TYPHOON survey with 20,000 computer simulations from the Illustris Project, the team discovered that NGC 1365 grew from a small cluster into a giant spiral through continuous mergers with smaller dwarf galaxies.

The key findings also include:

• The central region formed very early in cosmic history.
• The galaxy grew over 12 billion years by "consuming" smaller dwarf galaxies.
• The outer spiral arms are relatively young, forming only within the last few billion years.
• Oxygen patterns are shaped by star formation, supernova explosions, gas flows, and galactic mergers.

According to Lars Hernquist, Mallinckrodt Professor of Astrophysics at Harvard and a CfA astronomer, "This study shows that the astronomical processes we model on computers are shaping galaxies like NGC 1365 over billions of years."

This new field “extragalactic archaeology” provides a new blueprint for understanding how galaxies, including our own Milky Way, formed and evolved over cosmic time.

This breakthrough will allow scientists to compare the Milky Way galaxy with other distant ones to determine the evolution of our galaxy.