Uryu Koji

写真a

Title

Professor

Researcher Number(JSPS Kakenhi)

40457693
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Current Affiliation Organization 【 display / non-display 】

  • Duty   University of the Ryukyus   Faculty of Science   Physics and Earth Sciences   Professor  

  • Concurrently   University of the Ryukyus   Faculty of Science   Physics and Earth Sciences   Professor  

  • Concurrently   University of the Ryukyus   Graduate School of Engineering and Science   Interdisciplinary Intelligent Systems Engineering   Professor  

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Graduate School 【 display / non-display 】

  • 　
    -
    1995.03

    The University of Tokyo  Graduate School, Division of General Culture  Doctor's Course  Completed

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Academic degree 【 display / non-display 】

  • The University of Tokyo -  Ph.D.

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External Career 【 display / non-display 】

  • 1997.08
    -
    1998.08

    Abdus Salam ICTP, post-doctoral researcher  

  • 1998.09
    -
    2000.08

    SISSA, post-doctoral researcher  

  • 2000.09
    -
    2002.08

    University of Wisconsin-Milwaukee  

  • 2002.09
    -
    2005.10

    SISSA, assegno di recerca  

  • 2006.01
    -
    2006.07

    University of Wisconsin-Milwaukee  

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Research Areas 【 display / non-display 】

  • Natural Science / Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics

  • Natural Science / Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics

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Research Theme 【 display / non-display 】

  • Relativistic Astrophysics and Gravitational Wave Physics

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Published Papers 【 display / non-display 】

  • Equilibriums of extremely magnetized compact stars with force-free magnetotunnels

    Koji Uryu, Shijun Yoshida, Eric Gourgoulhon, Charalampos Markakis, Kotaro Fujisawa, Antonios Tsokaros, Keisuke Taniguchi, Mina Zamani

    Physical Review D ( American Physical Society (APS) )  107 ( 10 ) 103016-1 - 103016-14   2023.05 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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      DOI

  • Evolution of equal mass binary bare quark stars in full general relativity: Could a supramassive merger remnant experience prompt collapse?

    Zhou E.

    Physical Review D ( Physical Review D )  106 ( 10 ) 103030-1 - 103030-7   2022.11 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

  • Methods for relativistic self-gravitating fluids: from binary neutron stars to black hole-disks and magnetized rotating neutron stars

    Tsokaros A.

    General Relativity and Gravitation ( General Relativity and Gravitation )  54 ( 6 ) 52-1 - 52-77   2022.06 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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      DOI

  • Magnetohydrodynamic Simulations of Self-Consistent Rotating Neutron Stars with Mixed Poloidal and Toroidal Magnetic Fields.

    Tsokaros A, Ruiz M, Shapiro SL, Uryū K

    Physical review letters ( Physical Review Letters )  128 ( 6 ) 061101 - 061101-7   2022.02 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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      PubMed

  • Evolution of bare quark stars in full general relativity: Single star case

    Zhou E.

    Physical Review D ( Physical Review D )  103 ( 12 )   2021.06 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

    　View Summary

    We introduce our approaches, in particular, the modifications of the primitive recovery procedure, to handle bare quark stars in numerical relativity simulations. Reliability and convergence of our implementation are demonstrated by evolving two triaxially rotating quark star models with different mass as well as a differentially rotating quark star model which has sufficiently large kinetic energy to be dynamically unstable. These simulations allow us to verify that our method is capable of resolving the evolution of the discontinuous surface of quark stars and possible mass ejection from them. The evolution of the triaxial deformation and the properties of the gravitational-wave emission from triaxially rotating quark stars are also studied, together with the mass ejection of the differentially rotating case. We find that supramassive quark stars are not likely to be ideal sources of a continuous gravitational wave as the star recovers axisymmetry much faster than models with smaller mass and gravitational-wave amplitude decays rapidly in a timescale of 10 ms, although the instantaneous amplitude from more massive models is larger. As with the differentially rotating case, our result confirms that quark stars could experience non-axisymmetric instabilities similar to the neutron star case but with a quite small degree of differential rotation, which is expected according to previous initial-data studies.

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Grant-in-Aid for Scientific Research 【 display / non-display 】

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