“A frenetic pace”. This is how astronomers from the European Space Agency (ESA) describethe activity of a newly identified very distant galaxy that was making stars at 2,000 times the rate of the Milky Waywhen the Universe was less than a billion years old. The simple fact of its existence, discovered thanks to the Herschel space observatory, challenges current theories about the evolution of galaxies.
The extreme distance to which the galaxy is, known asHFLS3, implies that its light had to travel for 13 billion years before reaching the Herschel detectors. For this reason, the appearance it presents in these images is what it was like in the infancy of the Universe, just 880 million years after the Big Bang, when the universe was 6.5% of its current age. Despite its young age, HFLS3 already had a mass equivalent to that of today’s Milky Way, about 140 billion times the mass of our Sun, in the form of stars or matter to form new stars. Today, 13 billion years later, it should have become one of the largest galaxies in the local Universe. And this fact makes it quite an enigma, since according to current theories about the evolution of galaxies, bodies as large as HFLS3 could not have formed until much later.
During the HerMES study, Herschel detected tens of thousands of massive galaxies in which new stars were forming. Dave Clements, from Imperial College London, and the rest of the authors of this studyHFLS3 caught the eye because “it was very bright and very red, compared to other similar objects”. The fact that the galaxy is very red in this context means that it shines brightly in the infrared wavelengths and that, due to the redshift effect in our expanding Universe, implies an extreme distance.
Subsequent observations with a series of ground-based telescopes confirmed that HFLS3 era the farthest galaxy of its kind ever detected, observed just 880 million years after the Big Bang, with a redshift of 6.34. And further, it turned out that HFLS3 was producing so many stars that it is what is known as a“peak starburst”: tEvery galaxy is active, to the point where intense radiation from younger stars sweeps the material on which they are feeding from the galaxy. In the current Universe there are no more environments like this. “Starbursts as early as HFLS3 produced the heavy elements from which later generations of stars and galaxies would form, and much of the matter we know today,” the astronomers explain.
Astronomers think that phenomena like this were extremely unusual even in the infancy of the universe. The simple fact that an object like HFLS3 existed so early in the history of the cosmos challenges current theories about the formation of the first galaxies, according to which objects of this size could not have appeared until much later.
