The nuclei of the largest and most massive galaxies in the universe have already formed only 1.5 billion years after the big bang: this is the basic assumption of a new study conducted by Masayuki Tanaka, professor of astronomical sciences at the Graduate University for Advanced Studies and one of the operators of Japan’s national astronomical observatory. The researcher has in fact intercepted a distant and massive galaxy, containing more than 1 trillion stars, using the telescope of the Keck observatory in Hawaii in a region of the sky called Subaru/XMM-Newton Deep Field.
Using a particular instrument called MOSFIRE and present on the Keck telescope, the researcher obtained a very precise measurement, in the near infrared spectrum, of the light of this galaxy and discovered that it was emitted only 1.5 billion after the big bang. He also discovered, and perhaps this is the most important information, that the stellar formation within this galaxy seems already suppressed and ended so much that, in jargon, we can speak of “dying galaxy” because it is no longer active in terms of stellar production.
This information, in fact, tells us that the central nucleus of this galaxy had already formed and was mature and this in some ways is surprising considering the so remote period we are talking about. Moreover, this study confirms that our understanding of how galaxies are formed and how they grow, especially the largest and most massive ones, is still limited as Tanaka himself admits.
In any case this identification and analysis of this galaxy so far away and massive has provided several details that will help astronomers to understand more about how the “extinction” of galaxies happens, as explained by Francesco Valentino, one of the authors of the study and professor at the Cosmic Dawn Center (DAWN) in Copenhagen. What astronomers really want to answer is how and when the first “dead” galaxy of the universe appeared, one of the most interesting and intriguing questions regarding the whole field of studies on the so-called “primordial universe”.