A study led by the Astrophysics Institute of Andalusia (IAA-CSIC), for which the Gran Telescopio Canarias was used, has detected an unusually energetic radiation in a nearby, metal-poor galaxy, a finding that points to physical processes not yet explained and that would allow us to understand the mechanisms of the first galaxies in the cosmos.
The research has focused on the galaxy IZw18, a compact and exceptionally poor object in heavy elements, whose composition resembles that of the early universe and contains little more than hydrogen and helium, the simplest elements in the periodic table.
The IAA-CSIC study has detected, for the first time in this galaxy, an unusual emission line that reveals a much more energetic radiation than expected near the central region.
"The most striking thing is that the region where this highly energetic radiation appears does not coincide with the main group of common stars, such as those we usually see in other galaxies, which could point to a different origin," explained the principal investigator, Antonio Arroyo-Polonio.
This expert added that the gas in that area behaves very agitatedly, which reinforces the idea that these high-energy sources not only illuminate the gas, but also push it and generate fast and irregular flows.
The finding, published in The Astrophysical Journal Letters, suggests the presence of extreme physical processes that have not yet been explained.
IZw18 is a galaxy that, with a diameter of about 6,000 light years, is small compared to other galaxies, although it is still more than four trillion times larger than Earth.
In terms of energy, it emits in a single second more than 100,000 million times the amount that all of humanity has consumed since the beginning of civilizations.
Its gas, very poor in heavy elements, is subjected to extreme conditions since it is in highly energetic states due to the intense radiation emitted by the stars and other luminous sources inside it.
To study the ionized gas, the team has analyzed the so-called emission lines, a type of 'luminous footprint' that indicates which atoms are present in the gas and how many electrons they have lost.
This work combines observations from the MEGARA instrument, installed on the Gran Telescopio Canarias, and the MIRI instrument, on board the James Webb Space Telescope (JWST).
"The fact of being able to study this light, which has traveled millions of years to us, analyze it with this precision and obtain clues about the energy of the stars that generated it is, simply, incredible," added Arroyo-Polonio.
The team has also highlighted that the important thing now is to continue studying the ionization sources of this galaxy because it represents a local window to the "early universe."
