The total brightness (contours), velocity along our line of sight (colors of top panel), and speed of random motions (colors of bottom panel) of DEIMOS COSMOS 818760.
As part of the multinational ALPINE collaboration, scientists at the Kavli Institute have discovered a system of three galaxies merging together when the universe was only 1.3 billion years old.
The ALPINE program (ALMA Large Program to INvestigate CII at Early times) is an extensive project using the Atacama Large Millimetre Array (ALMA) to look at the ionized carbon emission (tracing regions that are actively forming stars) from 118 galaxies as they were ~1-1.5 billion years after the Big Bang. One of the primary goals is to characterize the dynamics of each galaxy in the sample, including how many are merging with other galaxies and how many feature regular rotating disks.
One of the galaxies in this sample (named DEIMOS COSMOS 818760), features three clumps of emission. From the way the clumps are distributed, how they are moving, and by comparing them with simulations, they are interpreted as three galaxies that are merging together in the early Universe. The two brightest sources are close together and show signs of interaction, while the third source is slightly weaker and more distant. The discovery of such complex interactions between galaxies in the early Universe provides previous information for understanding the early formation of galaxies and of their subsequent evolution.
Only a handful of triple mergers have been detected in the early universe, and further analysis of the ALPINE data is sure to reveal more.
The investigation of this galaxy was led by Gareth Jones, a postdoctoral research associate at the Kavli Institute, and the results were published in this week's issue of Monthly Notices of the Royal Astronomical Society: Letters - https://academic.oup.com/mnrasl/advance-article-abstract/doi/10.1093/mnrasl/slz154/5582601.
This is the very first paper published by the ALPINE collaboration and it is opening a sequel of several other papers that will be published in the coming months presenting various other important results that provide new important information on the primeval stages of galaxy evolution.
The ALPINE project is led by Olivier Le Févre.
