A new galaxy, which is likely to be very young by cosmic standards, has been discovered thanks to the power of big data and machine learning.
The galaxy, captured by an international team studying data from the Subaru Telescope in Hawaii, has broken the record for the lowest oxygen abundance in any galaxy observed from Earth.
Extremely low oxygen abundance
The galaxy, called HSC J1631+4426, has an extremely low oxygen abundance of 1.6% solar abundance, meaning it breaks the previous record of the lowest known oxygen abundance in a galaxy.
This, the researchers explained in a press release, means that the stars in the galaxy likely formed very recently.
As galaxies that are still in the early stages of formation in the modern Universe are rare, the international team behind the new discovery searched for them using wide-field imaging data taken with the Subaru Telescope.
"To find the very faint, rare galaxies, deep, wide-field data taken with the Subaru Telescope was indispensable," Dr. Takashi Kojima, the leader of the team, explained.
The trouble with searching through this data manually is that it includes as many as 40 million objects. In order to overcome this problem, the team developed a machine learning method to pick out early-stage galaxies from the data. The system was specifically trained on galaxy colors expected from theoretical models.
A last-generation galaxy
Using the machine learning method, the team found HSC J1631+4426 located 430 million light-years away in the constellation Hercules and were surprised by the finding that the galaxy has an oxygen abundance of only 1.6 percent of that of the Sun.
"What is surprising is that the stellar mass of the HSC J1631+4426 galaxy is very small, 0.8 million solar masses. This stellar mass is only about 1/100,000 of our Milky Way galaxy, and comparable to the mass of a star cluster in our Milky Way," said Prof. Ouchi of the National Astronomical Observatory of Japan and the University of Tokyo.
The team's discovery backs up the theory that new galaxies are born in the present universe and weren't only formed by the Big Bang. However, standard cosmology also suggests that in the future universe, the cosmo's rapid expansion will mean that matter will not assemble by gravity.
So in HSC J1631+4426, the researchers may have discovered a last-generation galaxy — one of the last galaxies ever to form.