The mystery surrounding black holes has furthered to fuel the allure around studying them and while many black holes have been observed and studied, usually at the centres of galaxies, there still remains a great deal that is not known about them.
The various measurements that scientists have made have often pertained to size and location, but in a new study, European researchers set out to actually weigh a black hole, trying to determine the weight of these celestial bodies.
Researchers from the European Southern Observatory (ESO) using the Carma array of telescopes in California, US, sought to determine the exact mass of a black hole and deduce how the sheer size of a black hole affects the evolution of a galaxy. In this regard, they devised a novel approach that determined the mass of a black hole by the speed of the particles swirling around it. Of course, because black holes, as the very name denotes, cannot be observed directly, the astronomers in turn used the motion of the various objects around the black hole to measure its weight.
Detailing their research in the journal, Nature, the astronomers explained that the new method of measurement was based on observing the motion of dense, cold masses of gas, which emit microwave radiation, making the observation clearer to the astronomer’s telescopes. Other objects that could be used for the measurement include the stars around the black hole or electrically charged gas. However, observing either, according to the researchers, does not yield accurate results, and so using the dense, cold gas instead has given more exact data.
The ESO researchers turned to the observation of carbon monoxide gas - which gave results with the best resolution and studying the black hole NGC4526, the astronomers determined that it weighed “900 billion trillion trillion” tonnes or the equivalent of the mass of the same number of family cars.
Speaking about the research, Dr. Timothy Davis of the ESO said, "Galaxies and black holes seem to be related to each other; there's this relation between the mass of the black hole and properties of the galaxy. That's rather weird, because these black holes are tiny compared to galaxies; they don't weigh that much, and they're physically small - less than the size of our Solar System in a galaxy that's billions of times bigger. What we'd really like to understand is how these two components interact; why they care about each other at all. To do that, we need to be able to measure their masses, and compare them in all sorts of different galaxies. That will allow us to start answering these questions."