Astrophysicists have tracked gamma rays from the recently awakened microquasar black hole V404 in the constellation Cygnus and found that it produces large amounts of antimatter in the form of positrons, "evil counterparts" of electrons, according to an article published in the journal Nature.
Microquasars are thought to originate in binary stellar systems made up of a relatively large and short-lived star and its smaller companion. When a large star runs out of supplies of nuclear fuel, a black hole appears in its place, which begins to "steal" matter from its neighbor. Part of this matter is ejected in the form of an incandescent gas jet moving at near-light speed. So far, scientists have found only four microquasars in our Galaxy, and not a single one outside of it.
In June 2015, according to Thomas Siegert of the Institute for Extraterrestrial Physics in Garching (Germany) and his colleagues, one of the most famous microquasars suddenly awakened - the V404 system in the constellation Cygnus, which had been in hibernation until this moment for over 26 years.
This object, located about 6 thousand light-years from Earth, was discovered in the 30s of the last century, and since then it has experienced three powerful flares, allowing astronomers to study its structure in detail. It is a pair of an ordinary star with a mass of about 0.7 Sun and a black hole, which is about nine times heavier than our star.
Since June 15, this microquasar has increased in brightness to the point where it has exceeded the brightness of the Crab Nebula, the brightest X-ray object in the night sky, by 40 times. The flare lasted for about 11 days, which allowed scientists to study the quasar in detail using the orbiting X-ray telescopes Swift and INTEGRAL.
One of the main mysteries of V404 and other microquasars, Siegert says, is how they generate these powerful bursts of radiation and how they accelerate the matter they spit out to near-light speeds.
As the scientists explain, in recent years, their colleagues have discovered several different mechanisms for the acceleration of matter and the formation of energy radiation, each of which leaves its own characteristic trace in the spectrum of X-ray and gamma-ray flares generated by quasars and other compact objects. Siegert and his colleagues hoped to find them by analyzing how much energy was released during the V404 flare in different parts of the spectrum.
Analysis of the spectrum of the June flare revealed an unusual peak in the strength of X-ray radiation, which fell on waves with a length of 2.42 picometers (10 to minus 12 degrees of a meter), which "gave out" to scientists one of the sources of this radiation - a cloud of exotic electron-positron plasma generated by the collision of high energy gamma rays with each other.
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As the scientists note, during the outburst, every second in the vicinity of V404, 10 to 42 degrees of positrons were born, only a part of which collided with electrons and generated those X-ray waves that Swift and INTEGRAL saw.
A significant part of the antimatter particles, according to Siegert, should have been thrown into outer space along with the "spit out" matter, where these clouds of positron-electron plasma would gradually disintegrate, generating characteristic bursts of gamma radiation associated with mutual annihilation of positrons and electrons.
Such microquasars, according to the authors of the article, can be a source of mysterious positrons and the associated scattered X-ray radiation emanating from the center of our Galaxy, which scientists have not yet been able to explain. Apparently, the V404 system and its "cousins" are factories of antimatter that supply the Galaxy with scarce positrons. If this is true, then in the center of the Milky Way there should be from one to 10 thousand microquasars, scientists conclude.