Recently, the post-doctor Nai-Bo Zhang in the interdisciplinary research center of nuclear physics of school of space science and physics study the implications of the very recently reported mass M =Msun of PSRJ0740+6620 on the equation of state (EOS) of super-dense neutron-rich nuclear matter with respect to existing constraints on the EOS based on the mass M = 2.01 ± 0.04 Msun of PSR J0348+0432, the maximum tidal deformability of GW170817, and earlier results of various terrestrial nuclear laboratory experiments. This work is accepted and published in the Astrophysical Journal (IF: 5.580) in the title of “Implications of the Mass M = Msun of PSR J0740+6620 on the Equation of State of Super-dense Neutron-rich Nuclear Matter”.
Neutron stars are the compact objects with extreme conditions in the universe. It plays the role of bridge between nuclear physics and astrophysics and is a ideal platform for interdisciplinary research. Science the discovery of J0348+0432 in 2013, the maximum observed mass of neutron stars is 2.01 Msun. Recently, Cromartie et al. discovered the PSR J0740+6620 with mass M =Msun. In this work, three related questions are studied: 1) How much better can the J0740+6620 constrain the skewness parameter used to measure the stiffness of SNM at supra-saturation densities? 2) How much better can the J0740+6620 constrain the high density symmetry energy and the corresponding proton fraction in NSs at β-equilibrium? 3) How much tighter can the J0740+6620 constrain the pressure inside NSs predicted by the state-of-the-art nuclear many-body theories? The difficulties for some of the most widely used and previously well tested model EOSs to simultaneously predict both a maximum mass higher than 2.17Me and a pressure consistent with that extracted from GW170817 present some interesting new challenges for nuclear theories.
A serious of progresses have been made by interdisciplinary research center of nuclear physics recently: 1) Based on the parameterizations of symmetry energy and EOS of symmetric nuclear matter, a isospin dependent parameterized EOS is constructed and the constraints of astrophysical observations on the parameter space are studied by inverting the TOV equations (Astrophysical Journal, IF: 5.551). 2) Based on the observations of mass, radius, tidal deformability and causality condition, the constraints on the high density symmetry energy are extracted (The European Physical Journal A, IF: 2.481). 3) Based on the isospin dependent parameterized EOS, the effects of symmetry energy on the tidal deformability are studied (Journal of Physics G: Nuclear and Particle Physics, IF: 3.534).
The interdisciplinary research center of nuclear physics was founded by Prof. Shou-Yu Wang. The Joint supervisor regime is adopted to train the graduate students. This center pays attentions to the international communication and interdisciplinary research. Since this center starts the study of nuclear astrophysics in 2013, the research interests include: the rotational properties of neutron stars, the criterion to distinguish different kinds of compact stars, the cooling of neutron stars, constraints on the EOS and symmetry energy of nuclear matter, the binary neutron star mergers. So far, 13 papers related to the nuclear astrophysics have been published.
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