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View Full Version : A stiffer equation of state for neutron stars at very high densities?



trinitree88
2010-Jun-21, 04:41 PM
Equations of state describe the conditions in the interior of neutron stars. The authors find that their mathematical analysis determines a previously unknown contribution to repulsive forces in said stars, provide the spins of abutting trios of protons/neutrons/ mixes of both are axis aligned. This becomes larger at high densities.
Why is this interesting? Recent theoretical considerations have shown that an improved packing factor for neutron stars occurs if the nucleons assume a bean-shape rather than a sphere as the star is squeezed (lecture @ Center for Theoretical Physics @ MIT about ~ 4 years ago...speaker was German?? DESY?). Such bean-shaped nucleons would pack with axes somewhat aligned, further enhancing the effect. Neat. SEE:http://arxiv.org/PS_cache/arxiv/pdf/1005/1005.4412v2.pdf

baric
2010-Jun-21, 05:31 PM
According to the paper, this 3-body repulsive force decreases with the 4th power of the distance between neutrons. This obviously suggests it is negligent at large distances but becomes significant at neutron-star densities.

If this paper is accurate (it's far too technical for me to make a determination on that), then does it raise the mass limit required for cores to collapse into black holes?

trinitree88
2010-Jun-21, 07:32 PM
According to the paper, this 3-body repulsive force decreases with the 4th power of the distance between neutrons. This obviously suggests it is negligent at large distances but becomes significant at neutron-star densities.

If this paper is accurate (it's far too technical for me to make a determination on that), then does it raise the mass limit required for cores to collapse into black holes?

baric. That seems to be the implication. They are just taking the prudent route, leaving that conclusion alone for now, and, ...it gives something else to say in a follow-up paper which is also part of the art of publication. You don't want to lump all your best ideas in one paper, and to be fair....taking ideas in detail, one at a time, is easier for rookies to follow.