Ghost stars. Scientists about incredible space objects

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Ghost stars. Scientists about incredible space objects
Ghost stars. Scientists about incredible space objects
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General relativity provides for the existence of stars made of antimatter, stable bosons and dark matter. But they have not yet been found. Several scientific groups have suggested what such unusual objects might look like and how many there are in our Galaxy.

Anti-stars

According to modern concepts, in the first moments after the Big Bang, the formation of each particle of matter was accompanied by the appearance of the same, but oppositely charged particle of antimatter. Attracting to each other, they annihilated, but the substance turned out to be one billionth more. The entire material part of the cosmos was formed from it.

However, it is possible that unpro-annihilated clumps of antimatter remained in the Universe. Moreover, over billions of years, they could combine to form anti-stars. They should look like ordinary stars with only one difference - when particles of matter, for example, hydrogen atoms, hit them, characteristic pulses of gamma radiation will appear due to annihilation.

Scientists at the Institute for Astrophysics and Planetary Research at the University of Toulouse suggest looking for anti-stars for such gamma-ray bursts. Of the 5787 radiation sources recorded over ten years by the Fermi gamma-ray telescope and listed in the LAT (Large Area Telescope) catalog, unidentified and with a spectrum compatible with the annihilation of baryons and antibaryons were selected.

There were 14 of them. By combining the calculations with the modeling of the accretion of anti-stars, the researchers obtained the upper limit of the number of such objects in our Galaxy - 2.5 x 10-6. That is, for one million ordinary stars, there are no more than 2.5 anti-stars, provided that they look like ordinary stars.

Be that as it may, the authors emphasize: there is still no reliable information about antimatter in the Universe, and all constructions are purely theoretical.

Location of 14 potential antimatter stars in our Galaxy

Dark matter stars

It is estimated that dark matter accounts for approximately 85 percent of the material universe. But dark matter cannot be detected because it does not absorb, reflect or emit electromagnetic radiation. It is known from astronomical observations that a certain hidden mass changes the orbits of stars in galaxies, but no one has yet registered the particles that make up this hidden mass.

One of the hypotheses assumes that dark matter is not evenly distributed throughout the Galaxy, but is a scalar field with "clumps" - a kind of "dark stars" consisting of "darkinos" or "dark fermions".

Recently, Italian scientists from the International Center for Relativistic Astrophysics in Pescara (ICRANet) suggested that not a supermassive black hole but a core of dark matter is located in the center of our Galaxy. In their opinion, adopting this point of view, it is easier to explain the deviations of orbital velocities in the outer regions of the Milky Way, as well as the behavior of strange objects orbiting the center of the Galaxy, the so-called G-sources.

They have a very elongated orbit, they contract, then stretch and lengthen. It is believed that these are gas and dust clouds with stars located inside them.

Using the example of the orbits of one of these sources - G2 - and the S2 star, astrophysicists from ICRANet have demonstrated that these objects experience resistance as they move, and this is not consistent with the black hole model. As a result, a hypothesis arose about a clot of dark matter in the center of the Galaxy. On the outskirts, it becomes very thin, up to diffuse concentration.

The researchers believe that under certain conditions - exceeding the critical mass - a clot of dark matter gravitationally collapses into a supermassive black hole. Despite its exoticism, this hypothesis explains well one of the mysteries of cosmology - the rapid appearance of a large number of supermassive black holes in the early Universe.

Orbits of objects G orbiting a supermassive black hole in the center of our Galaxy (indicated by a white cross)

Bosonic stars

According to the Standard Model of physics, there are two types of particles: fermions, which make up the building blocks of matter, and bosons, which control interactions, forces that allow fermions to come together or, conversely, cause them to fly apart in different directions. All natural processes are based on these interactions - from nuclear decay to the refraction of light, including chemical reactions.

Ordinary stars are clumps of fermions - protons, neutrons, electrons. But purely theoretically, you can imagine bunches of bosons - photons, gluons, Higgs bosons or other, as yet unknown quantum particles.

Earlier this year, American astrophysicists hypothesized that the source of X-rays emanating from a group of nearby neutron stars known as the Magnificent Seven could be axions - bosons, proposed at one time to explain the violation of CP symmetry - the symmetry of the interaction between particles and antiparticles.

Axions are hypothetical particles that are a billion times lighter than protons and do not interact with ordinary matter, so they cannot be detected even with the most accurate instruments. These are prime candidates for the role of dark matter particles.

It is expected that axions in a magnetic field will decay into pairs of photons, so they suggest looking for them by excess radiation. This is indeed observed in some neutron stars and white dwarfs with strong magnetic fields.

Elementary particles

However, real bosonic stars created by the accretion of quantum particles do not emit - nuclear fusion reactions do not occur there. According to scientists, such objects are completely invisible. But, unlike black holes, they are transparent: there is no absorbing surface that would stop photons, and there is no event horizon - a boundary beyond which light does not escape.

The researchers speculate that bosonic stars may be surrounded by a rotating ring of plasma, similar to the accretion disk of a black hole. If so, then bosonic stars are like a luminous donut with a dark area inside - roughly like the M87 * black hole captured by the Event Horizon telescope, but with a much smaller dark area than the shadow of a black hole of the same mass.

Black dwarfs

Among the not yet discovered, but theoretically possible space objects, there are more real ones. It is known, for example, that when stars like the Sun run out of fuel for internal reactions, they turn into white dwarfs - very compact spheres the size of the Earth, where each cubic centimeter weighs about a ton.

White dwarfs continue to glow by inertia, but after a few billion years they will cool down completely and turn into black dwarfs - they do not emit in the visible range. This is the final stage in the evolution of stellar matter. It is believed that such cooled stars will necessarily appear in the Universe, but their time has not yet come.

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