New star described in a model combining relativity and quantum mechanics

March 9, 2018, International School of Advanced Studies (SISSA)
Credit: CC0 Public Domain

A new kind of star is reported in a study by SISSA postdoctoral researcher Raúl Carballo-Rubio. In a paper recently published in Physical Review Letters, Carballo-Rubio describes a novel mathematical model combining general relativity with the repulsive effect of quantum vacuum polarization. The result is a description of an ultra-compact configuration of stars that scientists previously believed did not exist in equilibrium.

"As a consequence of the attractive and repulsive forces at play, a massive star can either become a neutron star, or turn into a black hole" says Carballo-Rubio. In neutron stars, stellar is the result of the balance between gravity, an attractive force, and a quantum mechanical repulsive force called degeneracy pressure. "But if the star's mass becomes higher than a certain threshold, about three times the solar mass, the equilibrium would be broken and the star collapses due to the overwhelming pull of the gravitational force."

In the study, Carballo-Rubio investigated the possibility that additional quantum mechanical forces expected to be present in nature permit new equilibrium configurations for stars above this threshold. The additional force is a manifestation of the quantum vacuum polarization effect, which is a robust consequence of mixing gravity and mechanics in a semiclassical framework. "The novelty in this analysis is that, for the first time, all these ingredients have been assembled in a fully consistent model. Moreover, it has been shown that there exist new stellar configurations, and that these can be described in a surprisingly simple manner."

There are still several important issues that remain to be studied, including the observational applications of these results. "It is not clear yet whether these configurations can be dynamically realized in astrophysical scenarios, or how long would they last if this is the case." From an observational perspective, these "semiclassical relativistic stars" would be very similar to . However, even minute differences would be perceptible in the next generation of gravitational wave observatories: "If there are very dense and ultracompact in the Universe, similar to black holes but with no horizons, it should be possible to detect them in the next decades."

Explore further: A better way to model stellar explosions

More information: Raúl Carballo-Rubio, Stellar Equilibrium in Semiclassical Gravity, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.120.061102

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2.8 / 5 (6) Mar 11, 2018
Nevermind the fact that relativity and QM are incompatible.
2 / 5 (4) Mar 11, 2018
Increasing disturbing trend at and other web sites - tacking on a picture, any picture, that has nothing to do with the subject at hand. See Same stupid picture having nothing to do with the article.
1 / 5 (1) Mar 11, 2018
Increasing disturbing trend at and other web sites - tacking on a picture, any picture, that has nothing to do with the subject at hand.

Yes. Some are very misleading and detrimentally so.
Da Schneib
1.8 / 5 (5) Mar 12, 2018
One of the things not to lose sight of here is that this doesn't mean black holes are theoretically excluded. It just means that there are other things between BHs and neutron stars that we haven't found any demonstrable examples of; and we're not even sure they're stable solutions, so don't hold your breath until this math all gets worked out.

The paper is open access at arXiv:
4 / 5 (4) Mar 12, 2018
Still there "aether guy"???
It's Mackita now... aren't you tired of writing the same nonsense over and over for years?
Spaced out Engineer
not rated yet Mar 12, 2018
Nevermind the fact that relativity and QM are incompatible.

Yes, relativity is wrong, but useful enough for all intensive purposes in some dimensialities, namely those of the 4th kind. A reduction whose illusion tells us there is more to time, whether we say by the collectively exhaustive or the maximally extended.

You bring the integer of dimension. I'll bring the mirroring of features. We will get by and by.

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