TY - JOUR
T1 - Locating ergostar models in parameter space
AU - Tsokaros, Antonios
AU - Ruiz, Milton
AU - Shapiro, Stuart L.
N1 - This work was supported by National Science Foundation Grant No. PHY-1662211 and the National Aeronautics and Space Administration (NASA) Grant No. 80NSSC17K0070 to the University of Illinois at Urbana-Champaign. This work made use of the Extreme Science and Engineering Discovery Environment, which is supported by National Science Foundation Grant No. TG-MCA99S008. This research is part of the Blue Waters sustained-petascale computing project, which is supported by the National Science Foundation (Grants No. OCI-0725070 and No. ACI-1238993) and the State of Illinois. Blue Waters is a joint effort of the University of Illinois at Urbana-Champaign and its National Center for Supercomputing Applications. Resources supporting this work were also provided by the NASA High-End Computing Program through the NASA Advanced Supercomputing Division at Ames Research Center.
PY - 2020/3/15
Y1 - 2020/3/15
N2 - Recently, we have shown that dynamically stable ergostar solutions (equilibrium neutron stars that contain an ergoregion) with a compressible and causal equation of state exist [A. Tsokaros, M. Ruiz, L. Sun, S. L. Shapiro, and K. Uryū, Phys. Rev. Lett. 123, 231103 (2019)PRLTAO0031-900710.1103/PhysRevLett.123.231103]. These stars are hypermassive, differentially rotating, and highly compact. In this work, we make a systematic study of equilibrium models in order to locate the position of ergostars in parameter space. We adopt four equations of state that differ in the matching density of a maximally stiff core. By constructing a large number of models both with uniform and differential rotation of different degrees, we identify the parameters for which ergostars appear. We find that the most favorable conditions for the appearance of dynamically stable ergostars are a significant finite density close to the surface of the star (i.e., similar to self-bound quark stars) and a small degree of differential rotation.
AB - Recently, we have shown that dynamically stable ergostar solutions (equilibrium neutron stars that contain an ergoregion) with a compressible and causal equation of state exist [A. Tsokaros, M. Ruiz, L. Sun, S. L. Shapiro, and K. Uryū, Phys. Rev. Lett. 123, 231103 (2019)PRLTAO0031-900710.1103/PhysRevLett.123.231103]. These stars are hypermassive, differentially rotating, and highly compact. In this work, we make a systematic study of equilibrium models in order to locate the position of ergostars in parameter space. We adopt four equations of state that differ in the matching density of a maximally stiff core. By constructing a large number of models both with uniform and differential rotation of different degrees, we identify the parameters for which ergostars appear. We find that the most favorable conditions for the appearance of dynamically stable ergostars are a significant finite density close to the surface of the star (i.e., similar to self-bound quark stars) and a small degree of differential rotation.
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U2 - 10.1103/PhysRevD.101.064069
DO - 10.1103/PhysRevD.101.064069
M3 - Article
AN - SCOPUS:85083794094
SN - 2470-0010
VL - 101
JO - Physical Review D
JF - Physical Review D
IS - 6
M1 - 064069
ER -