Holographic cold dense matter constrained by neutron stars

The equation of state (EOS) for cold dense matter inside neutron stars is investigated by using holographic QCD models that consist the Einstein-Maxwell-dilaton system and improved Karch-Katz-Son-Stephanov action flavor part. This method describing nuclear in $\mathrm{Einstein}\text{\ensuremath{-}}\mathrm{Maxwell}\text{\ensuremath{-}}\mathrm{dilaton}+\mathrm{Karch}\text{\ensuremath{-}}\mathrm{Katz}\text{\ensuremath{-}}\mathrm{Son}\text{\ensuremath{-}}\mathrm{Stephanov}$ framework different from Dirac-Born-Infeld Chern-Simons terms. Combining with Hebeler-Lattimer-Pethick-Schwenk intermediate EOS, hybrid EOS constructed. obtained located range defined low-density chiral effective theory, high-density perturbative QCD, polytropic interpolations between them, constrained astrophysical observations. square sound velocity reaches a maximum value larger than 0.8 region 2--5 times saturation baryon number density approaches conformal limit at high range. mass-radius relation tidal deformability are agreement measurements. possible mass star about $2.5\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ radius 12 km then. It noticed quark branch always unstable can produce stable branch. These results indicate even core NS, still confinement phase not favored.