At the center of almost every galaxy there’s a supermassive black hole, but how they formed and how they grow is still very unclear. Now researchers think that stellar explosions help this process.
Astronomers from the University of Tokyo and National Institute of Technology have looked at the very core of many galaxies and discovered that the growth of supermassive black holes is linked to supernovae within a dense gas disk a few hundred light-years from the black hole.
In a paper, published in the Astrophysical Journal, the team has modeled how the gas ends up falling onto the black hole. These disks are rich in stars, and when these stars go supernova the turbulence in the gas causes it to flow inwards, fueling the growth of the black hole.
“The central regions of faraway galaxies, comprising a few light years in scale, are hard to observe in detail because of their compactness, and there haven't been many studies showing how black holes grow due to the lack of extensive research,” said lead author Takuma Izumi in a statement.
“So, this outcome is a big step forward as we successfully revealed one aspect of that process.”
Supermassive black holes in galaxies are between one hundred thousand and billions of times the mass of the Sun. Although their mass is huge they are very compact. The heaviest one, with 40 billion solar masses only, extends to 240 billion kilometers (150 billion miles), about 223 light hours.
A link between star formation in the core and the growth of supermassive black holes was already strongly suspected, and this study provides more evidence to support it.
The research was possible thanks to the Atacama Large Millimeter/submillimeter array (ALMA), which allowed the team to look at the central regions of galaxies using radio waves.
“We hope to expand our research to farther expanses of the universe by utilizing the superb capability of ALMA to help us understand comprehensively the growth of supermassive black holes over cosmic time,” added Izumi.