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Xia, C.-J.*; Maruyama, Toshiki; Yasutake, Nobutoshi*; Tatsumi, Toshitaka*; Zhang, Y.-X.*
Physics Letters B, 839, p.137769_1 - 137769_5, 2023/04
Times Cited Count：1 Percentile：68.16(Astronomy & Astrophysics)Xia, C.-J.*; Maruyama, Toshiki; Yasutake, Nobutoshi*; Tatsumi, Toshitaka*
Physical Review D, 106(6), p.063020_1 - 063020_14, 2022/09
Times Cited Count：4 Percentile：49.9(Astronomy & Astrophysics)Muto, Takumi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Progress of Theoretical and Experimental Physics (Internet), 2022(9), p.093D03_1 - 093D03_37, 2022/09
Times Cited Count：0 Percentile：0.01(Physics, Multidisciplinary)Muto, Takumi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Physics Letters B, 820, p.136587_1 - 136587_6, 2021/09
Times Cited Count：5 Percentile：65.12(Astronomy & Astrophysics)no abstracts in English
Xia, C.-J.*; Maruyama, Toshiki; Yasutake, Nobutoshi*; Tatsumi, Toshitaka*; Zhang, Y.-X.*
Physical Review C, 103(5), p.055812_1 - 055812_13, 2021/05
Times Cited Count：13 Percentile：90.39(Physics, Nuclear)Xia, C.-J.*; Maruyama, Toshiki; Yasutake, Nobutoshi*; Tatsumi, Toshitaka*; Shen, H.*; Togashi, Hajime*
Physical Review D, 102(2), p.023031_1 - 023031_18, 2020/07
Times Cited Count：16 Percentile：74.34(Astronomy & Astrophysics)no abstracts in English
Muto, Takumi*; Maruyama, Toshiki; Tatsumi, Toshitaka*; Takatsuka, Tatsuyuki*
JPS Conference Proceedings (Internet), 26, p.024019_1 - 024019_4, 2019/11
Maslov, K.*; Yasutake, Nobutoshi*; Blaschke, D.*; Ayriyan, A.*; Grigorian, H.*; Maruyama, Toshiki; Tatsumi, Toshitaka*; Voskresensky, D. N.*
Physical Review C, 100(2), p.025802_1 - 025802_11, 2019/08
Times Cited Count：44 Percentile：97.28(Physics, Nuclear)The effect of pasta phases on the quark-hadron phase transition is investigated for a set of relativistic mean-field equations of state for both hadron and quark matter. The results of the full numerical solution with pasta phases are compared with those of an interpolating construction used in previous works, for which we demonstrate an adequate description of the numerical results. For each pair of quark and hadron matter models the critical value of the surface tension is determined, above which the phase transition becomes close to the Maxwell construction. This result agrees well with earlier theoretical estimates. The study is extended to neutron star matter in beta equilibrium with electrons and muons and is applied to investigate the effect of pasta phases on the structure of hybrid compact stars and the robustness of a possible third family solution.
Lee, T.-G.*; Yasutake, Nobutoshi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Proceedings of Science (Internet), 281, p.326_1 - 326_8, 2017/05
Muto, Takumi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
JPS Conference Proceedings (Internet), 14, p.020809_1 - 020809_3, 2017/02
Times Cited Count：0 Percentile：0.03(Astronomy & Astrophysics)Noda, Tsuneo*; Hashimoto, Masaaki*; Matsuo, Yasuhide*; Yasutake, Nobutoshi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
JPS Conference Proceedings (Internet), 14, p.020805_1 - 020805_3, 2017/02
Times Cited Count：0 Percentile：0.03(Astronomy & Astrophysics)Lee, T.-G.*; Nishiyama, Kazuya*; Yasutake, Nobutoshi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
JPS Conference Proceedings (Internet), 14, p.020808_1 - 020808_3, 2017/02
Times Cited Count：0 Percentile：0.03(Astronomy & Astrophysics)Yasutake, Nobutoshi*; Chen, H.*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Journal of Physics; Conference Series, 665(1), p.012068_1 - 012068_4, 2016/01
Times Cited Count：6 Percentile：88.68(Astronomy & Astrophysics)Noda, Tsuneo*; Yasutake, Nobutoshi*; Hashimoto, Masaaki*; Maruyama, Toshiki; Tatsumi, Toshitaka*; Fujimoto, Masayuki*
Acta Astronomica Sinica, 56(Suppl.), p.52 - 54, 2015/11
We show a scenario for the cooling of compact stars considering the central source of Cassiopeia A (Cas A). The Cas A observation shows that the central source is a compact star with high effective temperature, and it is consistent with the cooling without exotic phases. The Cas A observation also gives the mass range of 
. It may conflict with the current cooling scenarios of compact stars that heavy stars show rapid cooling. We include the effect of the color superconducting (CSC) quark matter phase on the thermal evolution of compact stars. We assume the gap energy of CSC quark phase is large (
MeV), and we simulate the cooling of compact stars. We present cooling curves obtained from the evolutionary calculations of compact stars: while heavier stars cool slowly, and lighter ones indicate the opposite tendency.
Muto, Takumi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Acta Astronomica Sinica, 56(Suppl.), p.43 - 45, 2015/11
Coexistence of kaon condensation and hyperons, which may be realized in neutron stars, is investigated on the basis of the relativistic mean-field theory combined with the effective chiral Lagrangian. It is shown that kaon-condensed phase in hyperon-mixed matter is plausible, but it leads to significant softening of the equation of state (EOS). We discuss indispensable effects which make the EOS stiffer so as to be consistent with recent neutron-star observations.
Yasutake, Nobutoshi*; Benic, S.*; Blaschke, D.*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Acta Astronomica Sinica, 56(Suppl.), p.85 - 87, 2015/11
We study quark-hadron phase transition in neutron stars. The finite-size effects of mixed-phase structure should be taken into account in the phase transition of multi-component system. The phase transition strongly depends on the models for quark and hadron matter, surface tension, neutrino fraction, and temperature. We find that with strong surface tension the equation of state (EOS) becomes similar to that of a Maxwell construction, while weak surface tension yields bulk Gibbs condition. We also find that the mass-radius relation obtained by our EOS is consistent to the observation.
Muto, Takumi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
EPJ Web of Conferences, 73, p.05007_1 - 05007_5, 2014/06
Times Cited Count：3 Percentile：69.82(Physics, Multidisciplinary)Possible coexistence of antikaons and hyperons in nuclei and in neutron stars is investigated based on the same interaction model within the relativistic mean-field theory. It is shown that the ground state of multi-strangeness nuclei is given by multi-hypernuclei without bound 
mesons. In neutron stars, on the other hand, kaon condensation appears in hyperon-mixed matter for a moderate potential depth, but it leads to significant softening of the equation of state. Some repulsive effect at high density should be taken into account so as to be consistent with recent observations of massive neutron stars.
Yasutake, Nobutoshi*; Lastowiecki, R.*; Benic, S.*; Blaschke, D.*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Physical Review C, 89(6), p.065803_1 - 065803_10, 2014/06
Times Cited Count：80 Percentile：97.6(Physics, Nuclear)Okamoto, Minoru*; Maruyama, Toshiki; Yabana, Kazuhiro*; Tatsumi, Toshitaka*
Physical Review C, 88(2), p.025801_1 - 025801_10, 2013/08
Times Cited Count：49 Percentile：92.61(Physics, Nuclear)In neutron star crust, non-uniform structure of nuclear matter is expected, which is called the "pasta" structure. From the recent studies of giant flares in magnetars, these structures might be related to some observables and physical quantities of the neutron star crust. To investigate the above quantities, we have numerically explored the pasta structures with a fully three-dimensional geometry and have studied the properties of low-density nuclear matter, based on the relativistic mean-field model and the Thomas-Fermi approximation. We have observed typical pasta structures for fixed proton number-fraction and droplet and rod for cold catalyzed matter. We have also explored the crystalline configuration of "pasta". Although it was believed that spherical nuclei (droplets) form a body-centred cubic lattice as a ground state, we have shown that a face-centred cubic lattice is energetically more favored than body-centred cubic lattice near the transition density to rod.
Sotani, Hajime*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Nuclear Physics A, 906, p.37 - 49, 2013/05
Times Cited Count：15 Percentile：68.29(Physics, Nuclear)Inside neutron stars, the hadron-quark mixed phase is expected during the first order phase transition from the hadron phase to the quark phase. The geometrical structure of the mixed phase strongly depends on the surface tension at the hadron-quark interface. We evaluate the shear modulus which is one of the specific properties of the hadron-quark mixed phase. As an application, we study shear oscillations due to the hadron-quark mixed phase in neutron stars. We find that the frequencies of shear oscillations depend strongly on the surface tension; with a fixed stellar mass, the fundamental frequencies are almost proportional to the surface tension. Thus, one can estimate the value of surface tension via the observation of stellar oscillations with the help of the information on the stellar mass.
