Massive black holes stop the creation of new stars
Just months ago, NASA's Chandra X-ray Observatory discovered record 20 million mph (32 million km/h) winds nearby a supermassive black hole. Now astronomers working on ESA's Herschel Space Observatory are suggesting that such incredibly strong winds - whose speed depends on the size of the black hole - are preventing the gas and dust in galaxies from forming new stars, explaining the link between the size of a black hole and the rate at which new stars are formed.
All large galaxies have a massive black hole at their core, but the relationship between its mass and the rate at which new stars in the galaxy are born has eluded astronomers for over a decade.
The Herschel Space Observatory set out to answer this question by observing galaxies so far away, that they appear to us as if the stars in their bulge are still forming. Herschel is carrying out imaging and spectrum analysis in the 60 to 700 µm wavelength range, a part of the spectrum that is relatively unknown, as it is mostly blocked by the Earth's atmosphere, but that is crucial to our understanding of star and galaxy formation.
The material near the edge of a massive black hole gets extremely hot and emits so much light over a wide range of wavelengths – from radio waves to x-rays – that it outshines all the light from rest of the host galaxy, except for the light in the wavelengths observed by Herschel.
By analyzing the data provided by Herschel, astronomers can estimate the rate at which new stars are being formed in the galaxy and then compare it to the data detected by NASA's Chandra X-ray satellite, which indicates the growth rate of the black hole.
The scientists say they have only analyzed a small fraction of the data gathered by Herschel, but a clear pattern has already emerged. Galaxies with larger black holes seem to form new stars more rapidly, but the fastest-growing black holes appear to be in galaxies with very little star formation.
This suggests that once the radiation coming from the black hole reaches a certain threshold, it tends to discourage star formation in its galaxy, most likely because of the devastatingly fast winds that are being formed around the edges of the black hole.
A paper detailing the findings has been published on the journal Nature.
Source: UK Space Agency