At the Roque de los Muchachos Observatory (Garafía, La Palma), there has been a surprising and incomparable spectacle: the detection of one of the brightest galaxies ever observed. Thanks to the Gran Telescopio Canarias (GTC), it has been possible to measure a very strong emission in the far infrared. It is the brightest of the submillimeter galaxies (with a high rate of star formation), and one of the brightest ever observed.
This has been achieved by a team of scientists from the Instituto de Astrofísica de Canarias (IAC), led by researcher Anastasio Díaz-Sánchez from the Polytechnic University of Cartagena (UPT).
The observed galaxy stands out for having a high rate of star formation. It is forming stars at a rate of a thousand solar masses per year ; a much faster rate than the Milky Way, which is forming stars at a rate of twice a solar mass per year. According to the IAC astrophysicist and co-author of the article, Susana Iglesias-Groth: “these types of objects harbor the most powerful star formation regions known in the universe and the next step will be to study their molecular content.”
The multiple images of the discovered galaxy are indicated by white arrows (the scale of the image, in arc seconds, is shown in the lower right).
The phenomenon of the gravitational lens
How can galaxies so far away be detected and observed? Thanks to an effect known as gravitational lensing , a phenomenon that allows the bodies of the universe to be perceived as enlarged , due to the effect of other bodies, in this case, a group of galaxies between the Earth and the observed galaxy.
As the UPCT researcher and first author of the article, Anastasio Díaz Sánchez explains: “thanks to the gravitational lens, the galaxy appears 11 times bigger and brighter than it really is , and we see it as several images in an arc centered on the densest part of the cluster, which is known as an ‘Einstein ring.’ The advantage of this type of amplification is that it does not distort the light spectrum, so it can be studied for these objects as distant as if they were much more close”.
According to Einstein’s General Theory of Relativity, the phenomenon of gravitational lensing occurs when a ray of light passes near a very massive object , the gravity of the object attracts the photons and deviates them from their initial path. It is comparable to that produced by lenses in light rays, and acts as a kind of magnifying glass , changing the size and intensity of the apparent image of the original object.
The fact that the galaxy is so bright, its light is gravitationally amplified, and it has multiple images allows us to examine its internal properties that would not otherwise be possible with such distant galaxies.
“In the future we will be able to carry out more detailed studies of their star formation using interferometers such as the Northern Expanded Millimetry System (NOEMA / IRAM), in France, and the Atacama Large Millimeter Array (ALMA) in Chile” concludes IAC Researcher Helmut Dannerbauer, who is another contributor to this discovery.
