Bright green sources of high-energy X-ray light captured by the NuSTAR mission overlap the optical light image of the Whirlpool galaxy (center) and the accompanying M51b (bright greenish-white spot above)
In the nearby Whirlpool galaxy and the nearby M51b, there are two supermassive black holes that heat up and absorb the surrounding material. These two monsters should be the brightest x-ray sources in the review. However, a new study from the NuSTAR mission showed that they had a much smaller object of competition.
The Whirlpool Galaxy (M51a) delights with its beautiful star arms, rotating around the center. Neighboring and small galaxy M51b decided to grapple with the first to create a new galaxy - M51.
In the center of each of them is a supermassive black hole, which by mass exceeds solar one millions of times. The fusion process should push a large amount of gas and dust into these black holes, which heat the material by gravity and form bright discs. These formations should overshadow all the stars of the galaxy with their own brightness.
However, the brightness level of the radiation of black holes does not meet the expectations of scientists. Based on NASA's Chandra X-ray Observatory data, the researchers conclude that layers of gas and dust around the black hole in a larger galaxy are blocking additional rays. To solve the problem, they took advantage of NuSTAR's X-ray vision, but the black hole still seemed dull. How to explain this behavior? Most likely, black holes “flicker” during galactic mergers, rather than emitting constant brightness throughout the process. Blink hypothesis is a new idea in the study of black holes that has yet to be tested.
Small but bright!
Interestingly, in the process of merging in a large galaxy (M51a), an object was found that is millions of times smaller than any black hole, but shines with equal intensity. The phenomena are not related, but form an amazing X-ray spectacle in M51.
A small X-ray source is a neutron star - a dense sphere of material left over from the explosion of a massive star. A standard neutron star is hundreds of thousands of times inferior in diameter to the Sun, and in width it covers the parameters of a small city. Here are just a teaspoon of such material weighs more than a billion tons.
The found neutron star may be burning so brightly because of the powerful magnetic fields it generates. In the picture you can consider other sources of x-rays, which can also be neutron stars.