Astronomers Detect Supermassive Black Hole at the Center of 2 Ultra-Compact Dwarf Galaxies
A team of international researchers led by astronomers from the University of Utah spotted a supermassive black hole at the center of two ultra-compact dwarf galaxies.
Their discovery, described in a paper published in The Astrophysical Journal, suggests that the presence of supermassive black holes at the center of dwarf galaxies is more common than previously thought, potentially doubling the known number of supermassive black holes in the universe.
"It's pretty amazing when you really think about it," said Chris Ahn, doctoral candidate in the Department of Physics & Astronomy, and lead author of the study, in a press release. "These ultra-compact dwarfs are around 0.1 percent the size of the Milky Way, yet they host supermassive black holes that are bigger than the black hole at the center of our own galaxy."
For the study, the researchers used the Gemini North telescope located on Mauna Kea volcano in Hawaii to measure the movement of stars in two dwarf galaxies named VUCD3 and M59cO. The researchers used the so-called adaptive optics technique to correct the distortions caused by the Earth's atmosphere, bringing the once blurry galaxies into focus.
The measurements they collected using the ground-based telescope are supplemented with the images captured by the Hubble space telescope. Using these images, they were able to measure the distribution of stars in each galaxy and create a computer simulation that best fit their observations.
The researchers found that the objects near the center of the two galaxies move much faster than those outside, a classic indicator of a black hole's presence. The supermassive black hole detected at VUCD3 has a mass equivalent to 4.4 million suns and makes up about 13 percent of the galaxy's total mass. On the other hand, the black hole detected at M59cO has a mass of 5.8 million suns and makes up about 18 percent of the galaxy's mass.
Overall, the two galaxies is the second and third ultra-compact dwarf galaxies confirmed to harbor supermassive black holes at their center. The discovery of these black holes suggests that all dwarf galaxies might also harbor supermassive black holes.