A mysterious one radio signal coming from the center of an ancient group of stars has recently attracted the attention of a group of scholars and astronomy enthusiasts spread throughout the world: apparently its origin is to be found in a specific point of the Milky Way located at approximately 14,500 light years from the Sun. According to the first hypotheses made by the experts, it could be either a pulsar, i.e. a rapidly rotating star with a large density of neutrons, or a medium-sized black hole, a particularly rare type which until to date it has only been theorized but never observed: in the latter case, therefore, it would be a discovery of great importance.
The radio signal was recently described in an article published in the journal “The Astrophysical Journal”, which refers to a study conducted by the Italian Alessandro Paduano, member of the Australian International Center for Radio Astronomy Research at Curtin University.
In reality it is, as often happens when space is studied, a discovery born by chance: the researchers from Curtin University were in fact engaged in examining theglobular cluster named 47 Tucanae using the Australia Telescope, the radio telescope operated by Csiro at the Paul Wild Observatory in New South Wales.
The so-called globular clusters are precisely ancient groupings of stars scattered throughout our Galaxy: the 47 Tucanae, specifically, is made up of well over a million stars enclosed in an area of just 120 light years. After an observation of approximately 450 hours, the unexpected discovery of the radio signal arrived, welcomed with enthusiasm by the experts. “If this signal turns out to be a black hole, it would be a very significant discovery and the first radio detection of a black hole within a cluster.”declared Alessandro Paduano.“Even if you think that i black holes of intermediate mass exist in globular clusters, one of them has not yet been clearly identified”. Supermassive black holes at the centers of galaxies can be as large as millions, or even billions, of suns. Medium-sized black holes, however, are the missing connection between stellar black holes, remnants of the death of giant stars, and supermassive black holes.
“This project pushed our software to its limits both in terms of data management and processing, and it was truly exciting to see the richness of science that these techniques made possible”explained Tim Galvin, researcher at Csiro and co-author of the paper on the study.