Since the James Webb Space Telescope began operating two years ago, astronomers have been using it to span millions of years in time, back to a moment they call the dawn of the universe, when the first stars and galaxies formed.
Last month, an international team of researchers working with the James Webb Space Telescope’s Advanced Deep Exogalactic Survey (JADES) said they had discovered the earliest and most distant galaxy ever discovered – a colorful, banana-shaped blob 1,600 light-years across. Astronomers say it was already shining brightly when the universe was still relatively young, just 290 million years old.
The new galaxy, called JADES-GS-z14-0, is one of a series discovered by Webb that includes early galaxies and black holes that challenge traditional models of how the first stars and galaxies formed.
“This discovery proves that luminous galaxies existed 300 million years after the Big Bang and are more common than expected,” the researchers said. Wrote in a paper Posted to the Online Physics Archive.
“Models of galaxy formation need to account for the existence of galaxies so massive and so luminous very early in the history of the Universe,” said the research team, led by Professor Stefano Cagnani of the University Normale Superiore of Pisa in Italy.
The galaxy was first discovered during a deep sky survey using Webb’s near-infrared camera, one of the telescope’s workhorse instruments. In a patch of southern sky known as the Jades Origin Field, about a quarter the size of the full moon, scientists discovered 11 galaxies that appear to date back to when the universe was less than 400 million years old — far older than they expected.
Subsequent studies by Dr. Caniani and his colleagues using the telescope’s infrared spectrometer showed that the wavelength of light from JADES-GS-z14-0 had been stretched by more than 15 times by the expansion of the universe (redshifted by 14 in astronomical terms), similar to the way a siren becomes lower in pitch as it speeds up. This means that the light was coming to us 13.5 billion years ago, starting shortly after the universe was born. (The universe is about 13.8 billion years old, according to cosmological calculations.)
The galaxy’s light is spread out in a diffuse region, suggesting that it comes from stars rather than the throat of a black hole. Its brightness is equivalent to the radiation of hundreds of millions of suns, an astonishing number that was formed and gathered in just 290 million years.
The starlight also contains the spectral signature of oxygen, which was not present when the universe was born. This means that the stars in this galaxy have gone through several cycles of birth, death and rebirth, which have provided the universe with the heavy elements we need to evolve and survive.
How this all happened in such a short time is a mystery, one that looms large among the many black holes in the sky. Some astronomers think supermassive black holes (formed by the collapse of primordial gas clouds) could be the seeds of galaxies.
In a blog post“With the Webb telescope, astronomers will likely discover many of these luminous galaxies over the next decade, and perhaps even earlier,” wrote Dr. Carniani and Kevin Hainline of the University of Arizona, another member of the JADES team. “We are excited to see the extraordinary diversity of galaxies that existed at the dawn of the universe!”
