After the Big Bang and the appearance of the first stars and galaxies, 1,000 million years later, the Universe once again underwent a cosmic ionization process. What or who was responsible for such an event?
For a long time, more than two decades, astronomers have pondered this, concluding that it was the galaxies that caused this reionization . Now, a new international study led by researchers from the University of Geneva (Switzerland) has found a compact galaxy with a considerable emission of ionizing photons -key in the transformation of the universe-, which will help to dispel doubts about the origins of our universe.
During these 20 years of research, no galaxy had ever been discovered that emitted enough radiation to give weight to this theory.
Astronomers focused on the so-called “green pea” galaxies discovered in 2007 and which are part of a rare and particular class of these clusters of stars, gas clouds, planets, cosmic dust, dark matter and energy from our nearby universe. If these “green pea” galaxies are very compact, they can host stellar explosions strong enough to eject ionizing photons. Thus, reviewing the Sloan Survey (with more than a million indexed galaxies), they identified about 5,000 galaxies that shared the characteristics of very intense UV radiation and robustness.
Having chosen five of these galaxies, the next step was to use the NASA / ESA Hubble Space Telescope to detect UV radiation, discovering that the galaxy J0925, located at a distance of 3 billion light years, was actually a “ejection ”Of ionizing photons, with an intensity never seen before.
Specifically, the “green pea” galaxy found has a particular signature, with its Lyman-alpha spectrum much narrower and more powerful than any of the known galaxies. This finding thus represents a new and interesting way to confirm the most widespread hypothesis in the scientific community and to delve into the beginnings of the universe.
The study has been published in the journal Nature.
