by Scientists discovered that three neutron starsborn in the fires of other exploding stars, have cooled surprisingly quickly, bringing us closer to understanding the exotic nature of the matter within the cores of these extreme objects.
The discovery was made by a Spanish team led by Alessio Marino from the Institute of Space Sciences (ICE-CSIC) in Barcelona, using European and American space telescopes that work with X-ray light.
A neutron star is the core of an extinct star supernovaand can be up to almost three times the the mass of our sun in a straight spherical volume about 6.8 miles (11 kilometers) across. All that matter packed into such a small area means that neutron stars are among the second densest concentrations of matter in the known universe black holes. To make that statement more relatable, consider how a tablespoon of neutron star material would be comparable to the mass of Mount Everest.
This extreme nature also means that the physics governing the interior of neutron stars is murky. These objects are first called neutron stars because their material is so compressed that it has a negative charge. electrons and positively charged protons get smushed together, overcome the electrostatic force between them to form a complete object of just neutral neutron. Deeper in the core of a neutron star, matter may be crushed to an even greater extent, creating exotic particles never seen before, such as hypothetical hyperons. Perhaps, according to the scientists, or a neutron itself could be trapped inside a neutron star, creating a soup of the universethe most basic particles: quark.
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What happens inside a neutron star is governed by the neutron star’s equation of state. Think of this as a playbook that determines the structure and internal composition of a neutron star based on things like its mass, temperature, magnetic field and so on. The trouble is, scientists have hundreds of options for what this equation of state could be. Since we can not replicate World the conditions inside a neutron star, testing the correct model is largely dependent on matching them with what astronomical observations tell us.
Now, however, the discovery of three neutron stars with significantly lower surface temperatures compared to other neutron stars of the same age has provided a major clue, allowing researchers to rule out three-quarters of the possible models for the neutron star’s equation of state the count in one. stroke. There are two of the neutron stars pulsars, which are rapidly spinning neutron stars that fire radio beams in our direction. The third neutron star, in the Vela Jr supernova museum, does not show pulsating behavior, but that may be because its radio jets are not pointing in our direction.
The neutron stars were detected at X-ray wavelengths at the European Space Agencyand XMM-Newton telescope and NASAand Chandra X-ray Observatory.
“The amazing sensitivity of XMM-Newton and Chandra made it possible not only to detect these neutron stars, but to collect enough light to determine their temperature and other properties,” said Camille Diez, who is XMM-Newton scientist at the European Space Agency, in a statement.
The hotter a neutron star, the more energetic its X-rays, and the more energetic its X-rays from these three neutron stars are pretty cold as far as neutron stars go. We say “cold,” but neutron stars are still incredibly hot, with temperatures ranging from 1.9 million to 4.6 million degrees Celsius (3.4 million to 8.3 million degrees Fahrenheit). However, for their young age, between 840 and 7,700 years based on the size and expansion velocity of the surrounding supernova remnants, they are considered extremely cold. Neutron stars are born with temperatures of hundreds of billions, or even trillions, of degrees, and while they cool, other neutron stars of the same age have temperatures twice that—sometimes hotter.
Neutron stars can cool by two mechanisms. One is through thermal radiation from their surfaces that allows heat energy to escape into the cold space. There is the other one neutrino emission, which steals energy from the core of a neutron star, and is thought to be responsible for the rapid cooling of this particular neutron star trio.
However, how quickly neutron stars can cool as a result of these mechanisms depends on the equation of state.
“The young age and cold surface temperature of these three neutron stars can only be explained by invoking a rapid cooling mechanism,” said one of the researchers, Nanda Rea from the Institute of Space Sciences and the Institute of Space Studies of Catalonia, in the statement. “Since enhanced cooling can only be activated by certain equations of state, this allows us to rule out a significant portion of the possible models.”
And they weren’t just; The team estimates that three-quarters of all possible models can be ignored following this result. The researchers were able to determine this by calculating cooling curves, which are essentially graphs that show how neutron stars cool with respect to time. The shape of the curve depends heavily on neutron star properties such as mass and magnetic field strength, so using machine learning, the team calculated the range of parameters that best describe each cooling curve, and then matched them. with the potential. equations of state, seeing which ones still match and which ones could be thrown out because there is no chance of matching the data.
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This process reduced the range of possible equations of state, but the results apply to more than just neutron characterization. stars. The behavior of matter on sub-atomic scales involves intense pressure, extreme temperature and crushing gravity quantum effects, too. There is currently a lack of scientists who quantum theory of gravityand such an equation of state for neutron stars could put us on the road to quantum and advanced effects.gravity physics together as one theory at last.
The results are described in a paper published on June 20 in the journal Nature Astronomy.
