Justin Spilker at the University of Texas at Austin, a co-author on the study, commented:
That’s a whopping large quantity of dust, considering the young age of the system.
The astronomers believe the larger galaxy’s pace of star formation was likely triggered by a close encounter with its slightly smaller companion, which already hosts about 35 billion solar masses of stars and is also forming stars at a rate of about 540 solar masses per year.
The new observations also allowed the researchers to infer the presence of a truly massive dark matter halo surrounding both galaxies. Dark matter is thought to provide the pull of gravity that causes the universe to collapse into structures such as galaxies, groups and clusters of galaxies and so on. By comparing their calculations with current cosmological predictions, the researchers found that this halo is one of the most massive that should exist at that time.
… when most of intergalactic space was suffused with an obscuring fog of cold hydrogen gas. As more stars and galaxies formed, their energy eventually ionized the hydrogen between the galaxies, revealing the universe as we see it today.
In any case, our next round of ALMA observations should help us understand how quickly these galaxies came together and improve our understanding of massive galaxy formation during reionization.