A new study has revealed a deeper insight into how the amount of galaxy’s mysterious dark matter determines the size of its central black hole.
According to the study conducted by the researchers from the Harvard Smithsonian Center for Astrophysics, the size of supermassive black holes in elliptical galaxies is possibly linked to the amount of dark matter in the halos of these massive galaxies.
Past researchers have shown that the size of the black hole has something to do with the dark matter halo, which a galaxy has. It wasn’t clear which kind of relationship had more bearing, and this is what the study sought out to clear up.
For their study, the researchers analyzed the data from the ROSAT X-ray satellite’s all-sky survey and the Sloan Digital Sky Survey. The researchers examined over 3,000 elliptical galaxies to find the link between black holes and dark matter halos. They turned to star motions to trace the weight of black holes in galaxies while x-ray measurements of hot gas around galaxies helped them to calculate how heavy dark matter halos were.
They concluded that the masses of black holes and dark matter halos had a stronger relationship compared to what stars and black holes had. This relationship is likely to be connected to how elliptical galaxies form and grow. An elliptical galaxy forms when a number of smaller galaxies are merged, with all their dark matter and stars mixing together. Since dark matter is heavy, everything else follows the mold it dictates, guiding how an elliptical galaxy will turn out.
Akos Bogdan, Einstein Postdoctoral Fellow at Harvard-Smithsonian Center for Astrophysics, and one of the authors of the study, said, “Because the dark matter outweighs everything else, it molds the newly formed elliptical galaxy and guides the growth of the central black hole. Each galaxy is surrounded by a halo of dark matter that weighs as much as a trillion suns and extends for hundreds of thousands of light years.”
The findings were published in the Astrophysical Journal.