Quark matter in neutron stars

Inside the neutron stars is the 'noodle nucleus' - an unusual state of matter, consisting of subatomic particles called quarks.

Physicists gather new data from analysis of gravitational waves formed during the collision of neutron stars in August 2017 (symbolized GW170817). The data show that the cores of neutron stars are so dense that the atomic nucleus ceases to exist, concentrating into quark matter. This is an important turning point in identifying extremists.

'The confirmation of the existence of the quark core in neutron stars is one of the goals of neutron star physics from about 40 years ago' - theoretical physicist Aleksi Vuorinen at Helsinski University (Finland), said.

The quark core can appear inside the neutron star.

Neutron stars are actually dead objects - including the remains of heavy stars, with masses between 8 and 30 times the mass of the Sun. When these stars turn into supernovas, most of their mass is thrown into space; and the core collapsed into dense objects. Protons and electrons in atoms are compressed into neutrons and neutrinos. Neutrino particles 'run' into space, leaving neutrons under high pressure. The neutrons bind to each other, forming a star with a dense nucleus, called a ' noodle nucleus'.

Scientists hypothesize that under temperatures and pressures high enough, neutrons also decay into quarks, creating a material called 'quark soup' . However, it is difficult to determine what is inside the neutron star. The collision of GW170817 from August 2017 is the one that caught the attention of astronomers, because the way the two stars change as they approach each other can reveal more details about the side structure. in of them.

Aleksi Vuorinen's team found that neutron stars, at least twice the mass of the Sun, show characteristics that indicate the presence of a quark core. 'There is a probability, though not great, that all neutron stars consist only of nuclear matter. However, we can assess that what kind of conditions are required for such a scenario. In short, maintaining dense nuclear material is unusual. For example, the speed of sound in such an environment must be approximately equal to the speed of light ' - Mr. Vuorinen explained.

The discovery of quark matter in neutron stars can help scientists better understand the youngest phase of the universe. Scientists believe that, within a few microseconds of the Big Bang (called the quark era) the universe was filled with a hot quark-gluon plasma 'soup'.