An international group of astrophysicists, which includes members of the MIPT, found that quasars, distant galactic nuclei, actively emitting through the activities of supermassive black holes in their centers, only seem very mobile. Understanding the “mobility” of quasars will allow more efficient use of them as “beacons” in satellite navigation systems and for other purposes.
Quasars are very actively emitting centers of galaxies, “upward” and “downward” from which they strike plasma jets dispersed to enormous (near-light) speed. Astronomers cannot see the supermassive black hole, which actively eats the substance and partially throws it out in the form of plasma jets. However, the most “energetic” photons still leave the core of such a galaxy and can reach Earth observers. In the optical range, it is possible to distinguish both the plasma jet and the glow around its source. In the radio range from the quasar, only a part of its “jets” is visible, directed at us.
It is easiest and most accurate to observe quasars in the radio range – using the method of radio interferometry with superlong bases. This is a kind of simulation of one giant radio telescope, which can be obtained by placing two conventional radio telescopes far apart (this is how this very long base comes about). Sometimes one of these radio telescopes can even be in space (an example is the Russian Radioastron, which has recently lost contact with Earth). However, it is difficult to interpret the results of such observations: for this it is necessary to accurately integrate data from different tools into one whole.
Therefore, the authors of the new work have developed an automatic procedure, a set of algorithms that analyze data directly from a group of telescopes. It turned out that the coordinates of the visible beginning of the plasma jet from the quasar (that is, in fact, the boundaries of the quasar itself) do not stand still, but oscillate back and forth along the direction of such a jet. One would think that the source itself, that is, the quasar, is moving. However, this is very doubtful. The active core of a galaxy is a huge object that cannot just change its position in space almost instantly.
Astrophysicists claim that such oscillations are a kind of illusion, and their sources – the nuclei of quasars – do not experience any real displacements in space.
Scientists believe that the cause of the “dancing” of a quasar is its jets, which from time to time become brighter. Observations have shown that the apparent shift of the nucleus of an active galaxy occurs simultaneously with such flashes. This may indicate that the flashes inject a denser plasma into the plasma jet and thereby create the illusion of quaking the quasar.
Using accurate data on the observed movements of quasars, astronomers will be able to correct astrometric measurements – take into account their “oscillations”, or rather, the illusory nature of such oscillations. Accordingly, scientists will have the opportunity to adjust the real coordinates of the quasars. This, in turn, will allow to obtain more accurate distances to distant stars, and more accurate satellite navigation systems, the effectiveness of which depends on a set of fixed coordinates of satellites and earth objects. And they, in turn, are calculated by astronomers using data on the position of distant quasars.
