:: OSEL.CZ :: – Neutron stars can be eaten from the inside by small black holes

It is unbelievable that astrophysicists engage in parasitology. But why not, anything in the universe is possible. According to a new study by American astrophysicists, the dark matter could at least in part be formed by populations of small endoparasitic black holes that are slowly eating out from inside a neutron star.

Is dark matter hiding inside neutron stars? Credit: NASA.

One possible candidate for the still mysterious dark matter is primordial black holes. These could exist from the dawn of the universe and in sufficient quantity could create the effect of dark matter. Scientists are working hard to find them, but in vain. In fact, they are not among the candidates who now have the best betting odds. But black holes don’t have to be just primordial. In any case, they are still relatively promising, mainly because they are extremely difficult to find when they are not feeding on matter.

Stuart L. Shapiro. Kredit: University of Illinois.

Stuart L. Shapiro.

Kredit: University of Illinois.

Stuart Shapiro of the University of Illinois at Urbana-Champaign and his colleagues came up with the idea that dark matter could be associated with a population of black holes that could be hidden inside neutron stars. And devour them from within, like astrophysical parasites. There are two scenarios for endoparasitic black holes. According to one of them, these are primordial black holes that have penetrated into the interior of a neutron star and have already remained there. The second scenario assumes that under certain conditions, matter inside neutron stars could collapse into small black holes. The authors talk about “dark matter particles” that could penetrate a neutron star and collapse into a black hole.

It doesn't look very good for primordial black holes.  Credit: NASA / ESA and G. Bacon (STScI).

It doesn’t look very good for primordial black holes. Credit: NASA / ESA and G. Bacon (STScI).

The black hole should eventually eat the neutrino star. It is not yet clear whether such systems with endoparasitic black holes really exist, Shapiro et al. but in any case, they calculated how long it should take them (accretion rate). They modeled the consumption of neutron stars for black holes of various sizes – from masses three orders of magnitude lower than the mass of a neutron star to masses of nine orders of magnitude lower. Neutron stars can reach a mass of about 2.3 Suns, so they were black holes with masses in the range of dwarf planets.

For a non-rotating neutron star parasitized by a non-rotating black hole, the ingestion of matter should have a spherical profile. According to Shapir’s team calculations, even very small black holes weighing around 10-21 The sun was to completely devour the neutron star, less than the Big Bang. Since we know populations of old neutron stars, this virtually eliminates the scenario with primordial endoparasitic black holes. But it doesn’t sink the whole idea of ​​endoparasitic black holes.

Literature

Science Alert 23. 2. 2021.

arXiv:2102.09574.s

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