Researchers Gábor Kasza, János Takátsy, and György Wolf from the Wigner Research Centre for Physics in Hungary have delved into the constraints on the equation of state (EOS) of cold, dense strongly interacting matter, using astrophysical observations. Their work, published in the journal Physical Review D, sheds light on the properties of neutron stars, which are the densest objects in the universe after black holes.
Neutron stars are unique laboratories for studying dense matter because they reach densities several times higher than normal nuclear density at nearly zero temperature. Since most neutron-star observables are sensitive to the EOS, observational data can place stringent constraints on the EOS of strongly interacting matter. In their study, the researchers investigated constraints arising from the mass of the heaviest observed neutron star, perturbative QCD calculations at asymptotically high densities, NICER mass-radius measurements, and the tidal deformability inferred from the binary neutron star merger GW170817.
The team parametrized the EOS and allowed its parameters to vary freely, using observational data to constrain the admissible parameter space. They found that neutron-star observations significantly restrict the EOS of dense strongly interacting matter. While the Neutron star Interior Composition Explorer (NICER) has already provided measurements for five pulsars, the associated uncertainties remain relatively large. In contrast, the existence of very massive neutron stars and constraints on the tidal deformability emerged as particularly powerful probes of the EOS.
For the energy sector, understanding the EOS of dense matter can have implications for nuclear energy and the development of advanced materials for energy storage and transmission. While the direct applications may not be immediate, the fundamental understanding gained from such research can drive innovation in energy technologies. The study highlights the importance of astrophysical observations in constraining the properties of matter under extreme conditions, which can have broader implications for various fields, including energy research.
Source: Physical Review D, Volume 106, Issue 10, “Astrophysical constraints on the cold equation of state of the strongly interacting matter” by Gábor Kasza, János Takátsy, and György Wolf.
This article is based on research available at arXiv.