Many believe that the great galaxies of the early universe would have plenty of "fuel" for the birth of new stars, but a recent finding suggests that this is not the case in all cases. Astronomers using the space telescope Hubble and the Atacama Large Millimeter / Submillimeter Array (ALMA), they discovered six early galaxies (about 3 billion years after the Big Bang) that were unusually "dead".
This means that they no longer had cold hydrogen, which is necessary for the formation of stars. This is the peak period for the birth of stars, according to the lead researcher Kate Whitaker, so the disappearance of this hydrogen is a mystery.
The team found the galaxies thanks to the powerful gravitational lens, using clusters of galaxies to magnify light from the early universe. Hubble located where the stars had formed in the past, while ALMA located cold dust (where hydrogen is located) to show where the stars would have formed if the necessary ingredients were present.
Galaxies are thought to have expanded since then, but not through star formation. Rather, they evolved through mergers with other small galaxies and gas. Any formation after that would have been limited for the most part.
The findings are evidence of the combined power of Hubble and ALMA, and also show the potential of Hubble decades after its launch. At the same time, it highlights the limitations of both technology and human understanding, raising a number of new questions.
Whitaker noted that scientists do not know why galaxies died so quickly or what happened and the fuel stopped. Was the gas heated, discharged or simply consumed quickly? It may take some time to provide answers, if the answers are still possible.