Research On Equation Of State Of Super Dense Matters Based On The Multi-messenger Astrophysical And Nuclear Data

The Equation of State(EoS)of dense matter over two times the saturation density is largely unknown for humans.Part of the reason is that the constraints from terrestrial nuclear experiments mainly concentrate on the matters that have density lower than two times the saturation density.Another part of the reason is the complexity problem en-countered in the theoretical calculations and the physical condition where the unknown degrees of freedom(such as pion and deconfined quark matter)of matter appear.Nev-ertheless,according to the theoretical calculations,the matter in the neutron star may be denser than five times the saturation density,thus the neutron star becomes the nature and ideal place to study/constrain the EoS of super dense matters.Recent observational data of neutron stars have shed valuable light on the prob-lem of the EoS of super dense matters,including two milestones:1)The gravitational wave detectors LIGO/Virgo have detected the first double neutron star merger event GW170817 and measured mass and tidal deformability of each neutron star in the sys-tem in the mid 2017;2)X-ray detector NICER has measured the first precise mass and radius of PSR J0030+0451 simultaneously in the late 2019.We will use these data to constrain the EoS of neutron star and related macroscopic properties.Besides,we will discuss the possibility of that the deconfined quark matters exist in the core of neutron stars.In the first chapter,I will briefly introduce the research history of the EoS,data that can be used to constrain the EoS,the research methods and state of art of the field.In the second chapter,I will show results of constraining the EoS using multi-messenger data.We have used the piecewise polytropic method and the spectral de-composition method to jointly analyze the masses-radii measurement of pulsars,the gravitational wave data of GW170817,the lower limit of maximum mass of the static neutron star and the nuclear constraints.We got consistent results regardless of the parametrization method,these results include density-pressure relation,density-speed of sound relation,macroscopic mass-redshift relation and maximum central density of the neutron star.Then we used universal relations to calculate the tidal deformability,moment of inertia and gravitational binding energy at various masses.Especially,for a neutron star with mass 1.4M(?),we evaluated its radius and tidal deformability to be R1.4?12km and A1.4?400,respectively.Besides,the masses of isolated neutron stars that have precise gravitational redshift measurement were also determined.In the third chapter,I will show our expected radiated gravitational wave energy during the post-merger stage of the double neutron star systems observed today.We have used the fit formulas resulted from the numerical relativistic simulations to es-timate the expected radiated energy of GW170817 and GW190425 during their post-merger stage,and the detectability of these signals using the third generation gravita-tional wave detectors.Besides,We have used the post-merger gravitational wave energy of GW170817 to re-estimate the maximum mass of the static neutron stars.In the fourth chapter,I will discuss the existence of deconfined quark matters in the core of the neutron star and the possibility of quark star.We found that the deconfined quark phase can not show up in the density below 1.84 times the saturation density.We even found that the quark star model can explain the macroscopic observables avail-able today if we do not consider their difficulties in explaining the observed radiative processes.In the last chapter,I will draw conclusions and look into the future of the EoS constraining field.