The first observations of substances fluctuations near a black hole
Orbital X-ray observatory XMM-Newton of the European Space Agency has proved the existence of gravitational vortex around the black hole. This discovery helped another unit - NuSTAR, which belongs to NASA. State of the environment in the vicinity of the black hole over the past 30 years of active searches remained a mystery. Now, thanks to the work carried out at the astrophysicists will be able to map the behavior of matter is very close to the black hole. It could also open the door for future studies of the general relativity theory of Albert Einstein.
When matter rushes into a black hole, it starts to get very hot due to the friction of the particles present in this area. Before she gets into a hole and disappear forever, its temperature can reach several million degrees. In the space begins to emit X-rays. Since the 80s of last century, the first astrophysics using the earliest X-ray telescopes, discovered that X-ray beams coming from black holes with a mass comparable to the mass of stars twinkling. And it should flicker quite certain sequence. When it starts, dimming object and then clearing it happen once in ten seconds. Then days and weeks passed, and during the months of the oscillation frequency increased, reducing the oscillation period as long as the object is not started flashing up to ten times per second. After that flicker suddenly stopped completely.
Black hole disc
Artistic representation of the precession of the accretion disk around the black hole, that is, changes in mood motion of matter around it. Precessing the inner part of the disk is irradiated with high-energy matter, the rest of the radiation beams that makes obtain iron atoms in different parts of the disc. Source: ESA / ATG medialab
This phenomenon is X-ray astronomy has been called "quasi-periodic oscillations» (Quasi Periodic Oscillation (QPO)). Over the next 90 years of the last century, astronomers have figured out that these fluctuations are related to the gravitational effect, predicted by Einstein's general theory of relativity, when the spinning object creates around itself a kind of gravitational vortex.
"To make this easier to understand, you can compare the phenomenon with stirring honey into the pot with a spoon. Suppose that honey, a space, and a rotating spoon will pull him to her. In real life, the example of black holes, this means that any object moving in an orbit around a rotating object will experience a certain effect on his movement. If the orbit is inclined, this effect will be manifested in the form of precession. Time for which the orbit will return to its original state, is called a cycle of precession. "
In 2004, with the help of NASA Gravity Probe B project attempted to measure the effect of the so-called dragging of the inertial reference systems (Lense-Thirring effect). This effect is described by general relativity lies in the appearance of additional acceleration, similar to the Coriolis acceleration, that is, as a result, the forces acting on the test body moving in a gravitational field. Result Gravity Probe B was not accurate (although the design error was of the order of one percent, the effect of the electric charge has led to a deterioration of the relative error of measurement of the Lense-Thirring effect of up to 20 percent), but he confirmed the predictions of general relativity. The measured value of geodetic precession made - 6601,8 ± 18,3 mas / year, and the drag effect - -37,2 ± 7,2 mas / year (theoretically predicted values - 6606,1 mas / year and 39,2 mas / year ). This meant that the spacecraft will gradually turn around and complete a full cycle of precession for 33 million years. It is clear that the black hole this effect will be more pronounced because of its enormous gravitational field. According to calculations, the precession period, the black hole must be a few seconds or less. This result agrees well with the data of the quasi-periodic oscillations, astronomers began to suspect the relationship between these phenomena.
Astrophysicists have started to deal with this problem with the study of what is happening in the flat accretion disk surrounding the black hole. This CD is a well known fact that the substance accumulates in it and a spiral rushes into a black hole. While scientists have been aware of, which is close to the black hole of the accretion disk turns into a hot plasma in which the electrons break from their orbits in atoms. This substance is called the hot inner stream. Author ongoing research along with colleagues back in 2009 published an article that speculated that the quasi-periodic fluctuations caused by the precession of the flow of the Lense-Thirring effect. The relationship of these events is as follows: the smaller the internal flow, the closer to the black hole, he can come and thus the precession period becomes shorter. Another question is how to prove this relationship?
"We spent a lot of time trying to prove the relationship between these events. The answer to this question is as follows: the internal heat flow produces high-energy X-ray radiation, which irradiates the substance of the surrounding accretion disk, affecting the iron atoms, causing them to obtain a fluorescent lamp. Iron emits X-rays at a single wavelength, which is also called spectral lines. "
Since the accretion disk rotates, the spectral line of iron is distorted by the Doppler effect: approaching us with the disc goes into the blue spectrum, and receding from us side goes into the red range. If the internal flow really will precess, it will sometimes be seen on one side of the disk, then the other, making the spectral line of iron fluctuate. It was during this time and was involved in the work of the telescope XMM-Newton. Astrophysicists had to find an object for long-term observations, they chose a black hole H 1743-322 which showed chetyrёhsekundnuyu delay quasi-periodic oscillations. Using XMM-Newton, this object has been studied for 260000 seconds. In addition, within the 70,000 seconds for a black hole observed observatory NuSTAR.
"High-capacity NuSTAR were very important in these studies. This observatory has confirmed fluctuations of spectral lines of iron, besides the spectrum proved one feature that can be seen as a peak in the graph. She added further evidence to the precession. "
After this painstaking analytical process and the union of all the observed data together, the researchers found that the vibrations of iron lines correspond to the predictions of general relativity. Thus, it can be said that there had been direct observation of the motion of matter in a strong gravitational field close to the black hole. This was the first time in history, when it was possible to observe the effect of dragging of the inertial reference systems. This technique will allow astronomers to map the distribution of matter in the inner regions of accretion disks around black holes. Also, this discovery provides a powerful tool for testing general relativity. The fact that Einstein's theory is not tested in such strong gravitational fields. Therefore, if the astronomers will be able to understand the physics of matter, aspiring to a black hole, they can use it to test the predictions of Einstein's theory as precise as never before. But just in case, if the motion of matter in the accretion disk will be fully understood.
"If you can get to the bottom of astrophysics, only then will you really be able to check the general theory of relativity. However, deviations from this theory would be welcomed by most astronomers and physicists. It would be a concrete signal that there is a deeper theory of gravity. "
According to information: http: //www.jpl.nasa.gov/