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Sydney [Australia], April 23 (ANI): New research led by Indian-born researcher Dr. Anshu Gupta revealed that galaxies grow by eating their smaller neighbors.
Exactly how massive galaxies reach their size is not known, especially since they swell over billions of years.
But now a combination of observation and modeling by researchers led by Dr. Anshu Gupta of Australia’s ARC Center of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) has provided a vital clue.
In an article published in The Astrophysical Journal, scientists combine data from an Australian project called the Multiple Object Spectroscopic Emission Line Survey (MOSEL) with a cosmological modeling program running on some of the world’s largest supercomputers to catch a glimpse of the forces that create these ancient galactic monsters.
By analyzing how gases move within galaxies, Dr. Gupta said, it is possible to discover the proportion of stars made internally, and the proportion actually cannibalized from other parts.
“We discovered that in ancient massive galaxies, about 10 billion light-years away from us, things move in many different directions,” he said.
“That strongly suggests that many of the stars within them have been acquired from the outside. In other words, large galaxies have been eating up smaller ones,” added Gupta.
Because light takes time to travel through the universe, galaxies furthest from the Milky Way are seen at an earlier point in their existence.
Dr. Gupta’s team found that observing and modeling these very distant galaxies revealed much less variation in their internal movements.
“Then we had to find out why the larger ‘older’ and closer galaxies were so much more disordered than the ‘younger’, more distant ones,” said Dr. Kim-Vy Tran, second author ASTRO 3D, who also resides in Sydeney UNSW as Dr. Gupta.
“The most likely explanation is that in the billions of years that have passed the surviving galaxies have grown fat and messy by incorporating smaller ones. I think of it as large galaxies that have a constant case of cosmic munchies,” Tran added.
The research team, which included scientists from other Australian universities and institutions in the US. The US, Canada, Mexico, Belgium, and the Netherlands modeled on a specially designed set of simulations known as IllustrisTNG.
This is a multi-year international project that aims to build a series of large cosmological models of how galaxies form. The program is so large that it has to run simultaneously on several of the world’s most powerful supercomputers.
“The modeling showed that the younger galaxies have had less time to merge with each other. This gives a solid clue to what happens during an important stage of their evolution,” said Dr. Gupta. (AND ME)
