Astronomers at the McDonald Observatory at the University of Texas at Austin in the United States have discovered an unusually massive black hole at the heart of one of the Milky Way’s dwarf satellite galaxies, called Leo I. It is almost as massive as the hole. black of our galaxy, when in fact it is supposed to have smaller dimensions. The finding could redefine our understanding of how galaxies and all components of the universe evolve .
Leo I is a dwarf galaxy located in the constellation of Leo, which was only visually detected in the 1990s, because its proximity to the star Regulus, the brightest in the constellation, makes it difficult to visualize. Leo I forms the Local Group and is one of the farthest satellite galaxies of the Milky Way. It is also thought to be the youngest spheroidal dwarf galaxy in the Milky Way environment.
Although Leo I is 30 times smaller than the Milky Way, astronomers were surprised to observe that the black hole located in its center was huge, with practically the same mass as the one located in the heart of the Milky Way. According to a press release , they came to this conclusion by studying the dark matter profile of the satellite galaxy.
The scientists used a unique instrument called VIRUS-W on the Harlan J. Smith Telescope to find out if the density of dark matter increases towards the center of the galaxy. To do this, they measured the gravitational attraction on the stars: the faster the stars move, the more dark matter they would have locked into their orbits. They also cross-checked the data with previous studies of the dwarf galaxy , conducted with telescopes and older technologies.
The results of the new study, published in The Astrophysical Journal, were conclusive: the distribution of dark matter indicates that in the center of the small galaxy there is a gigantic black hole with a great gravitational influence. In turn, toward the galactic center the amount of inferred dark matter locked within the orbits of the stars skyrocketed.
Apparently, a combination of specific biases and outdated technologies would have meant that previous research on Leo I did not show the incredible size of its central black hole , almost comparable to that of the Milky Way. The discovery is unprecedented, since what is expected is a black hole of much smaller dimensions.
A GREAT UNKNOWN
Based on this finding, astronomers believe that it might be necessary to modify the models that explain the evolution of satellite galaxies. For example, such a massive black hole could be explained by a process of fusion : however, this phenomenon is believed to occur when black holes in smaller galaxies integrate with the black hole of a larger galaxy. This process takes place when the smallest galaxies are “coupled” to the largest, with the passage of time and the increase in gravitational influence.
Consequently, it is likely that there are unknown points in the history of Leo I and its contiguous galaxies. At the moment, the scientists concluded that there is no concrete explanation for the presence of this type of black hole in dwarf spheroidal galaxies. It is clear that despite the great scientific and technological advance the universe still has many intriguing mysteries in store for us.