Thermodynamic instabilities in dense asymmetric nuclear matter and in compact stars

14th Conference on Theoretical Nuclear Physics in Italy

Lavagno, A.^1 ; Drago, A.^2 ; Pagliara, G.^2 ; Pigato, D.^1

Department of Applied Science and Technology, Politecnico di Torino, Sezione di Torino, Torino, Italy^1

Dip. di Fisica e Scienze della Terra dell'Università di Ferrara, INFN, Sez. di Ferrara, Ferrara, Italy^2

关键词: Asymmetric nuclear matter;    Charge concentration;    Coexisting phasis;    High energy heavy-ion collision;    Liquid-gas phase transition;    Mechanical instabilities;    Nuclear equation of state;    Thermodynamic instability;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/527/1/012019/pdf
DOI  :  10.1088/1742-6596/527/1/012019

来源: IOP

【 摘 要 】

We investigate the presence of thermodynamic instabilities in compressed asymmetric baryonic matter, reachable in high energy heavy ion collisions, and in the cold β-stable compact stars. To this end we study the relativistic nuclear equation of state with the inclusion of Δ-isobars and require the global conservation of baryon and electric charge numbers. Similarly to the low density nuclear liquid-gas phase transition, we show that a phase transition can occur in dense asymmetric nuclear matter and it is characterized by both mechanical instability (fluctuations on the baryon density) and by chemical-diffusive instability (fluctuations on the electric charge concentration). Such thermodynamic instabilities can imply a very different electric charge fraction Z/A in the coexisting phases during the phase transition and favoring an early formation of Δ-particles with relevant phenomenological consequences in the physics of the protoneutron stars and compact stars. Finally, we discuss the possible co-existence of very compact and very massive compact stars in terms of two separate families: compact hadronic stars and very massive quark stars.