We know that there are black holes at the centers of most galaxies, but we have not been able to precisely determine how they influence the evolution of those galaxies. This new method is based on the speed of the molecules that are circling around the black hole, and it should give new insights into the mass of these gigantic objects.
The method might enable us to weigh a large number of black holes that we have in our vicinity, as relative as that term is on this scale. The first attempt at using this method has resulted in the weighing of such a phenomenon in the NGC4526 galaxy. It was determined that black hole has a weight of approximately 450 million Suns.
Up till now we haven’t been able to perform such measurements, and there are only 20 or so cases where we have tried to even estimate the weight of a black hole. Since we cannot see them, we have been relying on estimating their mass through observation of objects that are swirling around the hole itself. Most of such guesses have been made by the observation of starlight that comes from the stars in the vicinity of the black hole.
Basically, we used to measure the speed of the stars that are closer to the hole, and compare that speed to the speed of the stars that are farther away. This method, however, had its failings, for one the stars that are moving in the opposite direction than the swirl would only disrupt the measurement and make it even less precise than it initially was.
Another, similar method was based on the observation of the electrically charged gasses. Even though not exactly too precise itself, this method offered a way to at least avoid some of the blurring of the measurement. However, both of these approaches were only useful for the black holes that are quite near to us.
The new method is based on analyzing the dense and cold gasses which are emitting the radiation in the microwave parts of the electromagnetic spectrum and which don’t have as much random motion that would blur the measurements. European astronomers have been using the Carma telescope to find the radiation which is emitted by the carbon monoxide molecules.
They were analyzing the NGC4526, and trying to map out the radiation coming from the black hole at the center of the galaxy. As it turned out, the hole was quite a bit more massive than they expected, with some 900 billion trillion trillion tons.
This new insight, and many similar that will follow, should give us better understanding of the interactions of the galaxies and the black holes within them. It is already known, and even fairly obvious, that objects of such a huge mass and gravity must have enormous influence on their surrounding, but this way, we will be much better equipped to measure that influence and understand exactly how far it reaches.