Index – Tech-Science – Gravitational waves showed a never-before-seen celestial body

The LVK gravity observatory system detected a particularly rare cosmic collision last May. One of the participants in the encounter was a neutron star, we don’t know what happened to the other. All we know is that its mass falls between the possible solutions.

Gravitational waves were predicted by the general theory of relativity, meaning a wave-like change in the curvature of space-time caused by accelerating masses. Since 2015, we have been able to observe them from very small variations in the arrival time of very sensitive laser pulses.

Gravitational waves as we know them today arise from the collision of very dense and compact celestial bodies. Two types of these are possible: the neutron star and the black hole.

Neutron stars form when giant stars collapse at the end of their lives. When the fusion fuel runs out, the energy also runs out, and a lot of material falls to the star’s core, from where it flies away in a supernova explosion. After the explosion, a super-dense stellar core remains, which can be at most two and a half times the mass of the Sun, but in a sphere with a diameter of 20 kilometers. It’s really compact,

A black hole is a well-known celestial body with extremely strong gravity, whose escape velocity exceeds the speed of light, meaning that light does not escape and a lot of other strange things happen to space, time and the laws of physics. Black holes can vary in size from one-tenth of a millimeter to supermassive black holes fifty billion kilometers in diameter.

The upper limit of the mass of neutron stars is 2.2-2.5 solar masses and the smallest known black holes are 5 solar masses.

During the analysis of the data recorded by the Ligo, Virgo, and Kagra gravitational wave observatories in May 2023, an event was identified, which was given the signal GW230529. The usual choreography of such events is that two compact celestial bodies come close to each other and orbit each other with increasing speed until they finally collide.

The calculations showed that one of the participants in the GW230529 merger, which occurred 650 million light-years away from us, was a celestial body with 1.2 and 2 solar masses, clearly a neutron star. The other participant was between 2.5 and 4.5 solar masses—strangely right in the gap between possible masses.

According to the astronomers, what they detected is probably a very rare and very small black hole. The reason for the surprising result is that we have been able to observe gravitational waves for barely a decade, and before that we inferred the properties of such celestial bodies from electromagnetic properties – the concept of the gap between the masses dates back to the turn of the millennium, but it can already be seen that this region is not as empty as we might have thought.

Like neutron stars, black holes are formed from stellar explosions. However, the newly detected superlight black hole does not fit into the model of the evolution of stars. According to Ligo’s Evan Goetz, one possible explanation is that it’s a black hole

from a massive neutron star.

The massive celestial body falling into the gap was detected for the first time in 2020 with a gravitational wave detector – its exact location could not be measured at that time, because only one member of the detector system was working. THE In the case of GW230529, observations using other methods can help solve the riddle.

The Ligo, Virgo and Kagra observatories have undergone major technical development in recent years, which significantly increased the sensitivity of their detectors. After a short maintenance period, the scientific work will start again in April this year. If all goes well, the number of observed gravitational waves could reach two hundred by next February.

(Science, Science Alert, Space.com)

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