Clandestine Black Hole May Represent New Population
Scientists discovered another unknown binary star system with its own low-mass star and a black hole lurking in the universe.
Astronomers combined data from NASA's Chandra X-ray Observatory, the Hubble Space Telescope and the National Science Foundation's Karl G. Jansky Very Large Array (VLA) to find out that there is a peculiar source of radio waves originally thought to be a distant galaxy.
As it turns out, the source is a nearby binary star system with its low-mass star and a black hole. This discovery led the astronomers to believe that there are vast numbers of galaxies that remain undiscovered until today.
Astronomers already knew about the VLA J2130+12 for decades, but they thought it is just and empty galaxy. But recent measurements prove that the initial theory was wrong. To come up with the findings various instruments were used including the EVN (European Very Long Baseline Interferometry Network) telescopes and the NSF's Green Bank Telescope and Arecibo Observatory.
VLA J2130+12 is 7,200 light years away and is still within the Milky Way Galaxy. Chandra revealed that it emits small x-rays while the latest data states that the source remains bright in radio waves. A supermassive black hole, few times the mass of the Sun, is also slowly pulling in materials from a star. Because of the partial feeding, it wasn't originally considered as a black hole.
"Usually, we find black holes when they are pulling in lots of material. Before falling into the black hole this material gets very hot and emits brightly in X-rays," Bailey Tetarenko of the University of Alberta, Canada said in an interview with NASA. "This one is so quiet that it's practically a stealth black hole," Tetarenko added.
The only limit to the study is that it only covers a very small patch of the sky, that is why astronomers believe that there's more clandestine black hole population in and out of the Milky Way galaxy waiting to be discovered. There could be tens of thousands to millions of these supermassive black holes in the Galaxy, three to thousands of times bigger as what studies suggested before.
"Unless we were incredibly lucky to find one source like this in a small patch of the sky, there must be many more of these black hole binaries in our Galaxy than we used to think," co-author Arash Bahramian said in a statement. Some of these clandestine black holes can even be closer to Earth.
To find out if there are indeed other similar undiscovered black holes, a larger survey of the sky using the employed technique should be performed.