Small star produces 64 trillion kilometers of path in space

The discovery of this great feat may provide further insight into the origin of the relatively abundant positrons observed on Earth.

In 2020, scientists discovered it for the first time: a massive bundle of matter and antimatter in space, which appears to come from a pulsar. However, the entire length of the package remained a mystery. Simply because astronomers couldn’t get a complete picture of the beam using the Chandra X-ray Observatory.

Follow up notes
In February and November 2021, astronomers took another look at the beam. Follow-up observations allowed them to monitor it fully and determine its true size. The package appears to be at least 64 trillion kilometers long, and it will be announced soon Astrophysical Journal to read.

a stranger
strange size. Especially when you consider that the package comes from the little asterisk. It is related to the pulsar PSR J2030 + 4415, which is about 1,600 light-years from Earth. A pulsar is a rapidly rotating neutron star with a very strong magnetic field, which typically – as in the case of PSR J2030 + 4415 – is barely 16 kilometers in diameter. “It is amazing that a pulsar only 16 kilometers wide is able to form a structure so large that we can observe it from more than 1,000 light-years away,” said researcher Martin de Vries.

But it’s not just the beam’s astonishing size that has caught the scientists’ attention. The observations may also help explain the mystery of the Milky Way’s relatively abundant positrons.

antiparticles
Positrons are the well-known antiparticles of electrons. This means that positrons have the same mass as electrons, but have an opposite charge. For example, an electron is a negatively charged particle, while a positron is a positively charged particle. According to physics, every elementary particle contains such an antiparticle. But – fortunately, see box – elementary particles are much more abundant than antiparticles.

When a particle collides with its antiparticle, they annihilate each other. This means that they mutually destroy each other. Fortunately, there is no antiparticle for every particle, because then there would be none. Although we can be happy that there is an imbalance in the universe (there are more particles than antiparticles), it also raises an interesting and still unanswerable question. Because it is assumed that the big bang produced as many antiparticles as particles. And so, for years, physicists have been thinking about where all the antimatter has gone.

So the vast majority of the universe is made of “ordinary” matter rather than antimatter. However, this does not change the fact that researchers encounter relatively large numbers of positrons (anti-particles of electrons) in detectors on Earth. This raises the question of the source of these positrons. The researchers now suggest pulsars like PSR J2030 + 4415, based on their observations of the massive beam of matter and antimatter that this pulsar generates. The pulsar’s rapid rotation, combined with its strong magnetic field, turns it into a massive particle accelerator that generates electrons and positrons. Normally, these particles have a hard time escaping from a pulsar’s strong magnetic field. But the extremely long matter and antimatter beam now observed behind PSR J2030 + 4415 reveals that particles can sometimes escape from a pulsar’s grip. The researchers also think they know how this happens. They note that the pulsar is moving through space at a high speed – about 1.5 million kilometers per hour. This creates a shock wave of gas for the pulsar – comparable to the bow wave of a moving boat. But about 20 to 30 years ago, that shock wave stopped and was overtaken by the pulsar. This resulted in a collision between the pulsar’s magnetic field and the interstellar magnetic field. “This may have led to the particle leakage,” researcher Roger Romani said. “The pulsar’s magnetic field combined with the interstellar magnetic field and the high-energy electrons and positrons escaped through the gap created by this contact in the pulsar’s magnetic field.” As the particles move along interstellar magnetic field lines, they glow in X-rays. Thus the long-beam, now observed by the Chandra X-ray Observatory, was created.

The fact that pulsars generate positrons is not new in itself. Previously, researchers have detected large halos around pulsars, filled with positrons, among other things. However, these halos indicated that the positrons had difficulty escaping the pulsar’s grip. PSR J2030 + 4415 now shows that particles can still escape into interstellar space and eventually reach Earth.