The earliest known galaxy merger
Two of the universe's first galaxies collide, less than a billion years in.
- When
- Known to
- ± 20 million years
- Era
- Reionisation, Stelliferous
ALMA observations of B14-65666 at redshift 7.15 caught two galaxies in the act of merging, their gas and dust visibly disturbed. It is the earliest collision ever directly observed and confirms that galaxies were already growing by merger, not just by steady accretion, within the first billion years. The same process built every large galaxy that exists.