Butsuri
Online ISSN : 2423-8872
Print ISSN : 0029-0181
ISSN-L : 0029-0181
Volume 73 , Issue 9
Showing 1-23 articles out of 23 articles from the selected issue
Preface
Contents
Multi-Messenger Astronomy with Gravitational Wave Observation
  • [in Japanese]
    Type: Multi-Messenger Astronomy with Gravitational Wave Observation
    2018 Volume 73 Issue 9 Pages 618
    Published: September 05, 2018
    Released: April 27, 2019
    JOURNALS FREE ACCESS
  • Koji Arai
    Type: Multi-Messenger Astronomy with Gravitational Wave Observation
    2018 Volume 73 Issue 9 Pages 619-622
    Published: September 05, 2018
    Released: April 27, 2019
    JOURNALS FREE ACCESS

    On August 17th, 2017, three interferometric gravitational wave detectors of LIGO-Virgo collaboration observed the first gravitational wave signal from a binary neutron star merger. The constrained sky localization of the event allowed follow-up observations of the optical counterpart by telescopes. This was the moment that multi-messenger astronomy with gravitational waves became a reality.

    Download PDF (3899K)
  • Masaru Shibata
    Type: Multi-Messenger Astronomy with Gravitational Wave Observation
    2018 Volume 73 Issue 9 Pages 623-626
    Published: September 05, 2018
    Released: April 27, 2019
    JOURNALS FREE ACCESS

    On August 17, 2017, gravitational-wave telescopes detected gravitational waves from a binary neutron star merger. In this article, we outline the results of the gravitational-wave observation and their follow-up observations of electromagnetic counterparts, and then, we describe our interpretation for this event based on our numerical-relativity results.

    Download PDF (1107K)
  • Masaomi Tanaka
    Type: Multi-Messenger Astronomy with Gravitational Wave Observation
    2018 Volume 73 Issue 9 Pages 627-630
    Published: September 05, 2018
    Released: April 27, 2019
    JOURNALS FREE ACCESS

    GW170817, the first gravitational wave source from a neutron star merger, has also been observed by electromagnetic waves over a wide wavelength range. This marked the dawn of “multi-messenger” astronomy by the synergy of gravitational waves and electromagnetic waves. Neutron star mergers have been expected to synthesize elements heavier than iron, and emit optical/infrared signals by radioactive decays of newly synthesized elements. Therefore, optical/infrared observations of the counterpart of GW170817 provided unique information about nucleosynthesis in the neutron star merger. In this article, I review what we learned about nucleosynthesis in neutron star mergers and the origin of heavy elements in the Universe through the multi-messenger observations of GW170817.

    Download PDF (1865K)
  • Kenta Hotokezaka
    Type: Multi-Messenger Astronomy with Gravitational Wave Observation
    2018 Volume 73 Issue 9 Pages 631-634
    Published: September 05, 2018
    Released: April 27, 2019
    JOURNALS FREE ACCESS

    The first binary neutron star merger, GW170817, was discovered by Advanced LIGO and Virgo on the 17th of August 2017. This merger was followed by multi-wavelength electromagnetic counterparts including: γ-ray pulse, optical-infrared kilonova, and non-thermal afterglow. In this article, we focus on the interpretation of the radio and X-ray afterglow. The observed spectra are well described by a single power law, suggesting that synchrotron radiation arising from the shock formed between the merger outflow and interstellar medium. Measuring the light curve of synchrotron afterglow allows us to study the outflow’s kinetic energy and velocity. Unlike the typical GRB afterglow, the afterglow of GW170817 rises at ∝t 0.8 from~10 day to at least~100 day. We show that the observations currently support the scenario in which a quasi-spherical outflow with a velocity gradient produces the afterglow. It is also worth noting that a simple top-hat jet model is ruled out from the observed data. Finally, we demonstrate how VLBI observation will allow us to directly measure the size of the outflow.

    Download PDF (1171K)
  • Kunihito Ioka
    Type: Multi-Messenger Astronomy with Gravitational Wave Observation
    2018 Volume 73 Issue 9 Pages 635-639
    Published: September 05, 2018
    Released: April 27, 2019
    JOURNALS FREE ACCESS

    The gravitational wave event GW170817 from coalescence of two neutron stars is associated with various electromagnetic counterparts, and became a historical event telling the arrival of full-fledged multi-messenger era. In this manuscript, I explain the origin of the short gamma-ray burst sGRB 170817A simultaneously observed with this event. This event is much fainter than ordinary sGRBs, leading to hot discussions about its origin, whether it comes from a success jet observed from off-axis or a failed jet in penetrating the merger ejecta. We expect that the long-standing mystery of the origin of sGRBs will be finally resolved by future observations of X-ray and radio afterglows and gravitational waves. I also mention my struggle with the embargo on this event.

    Download PDF (6760K)
Reviews
  • Kenji Yasuda, Atsushi Tsukazaki, Yoshinori Tokura
    Type: Reviews
    2018 Volume 73 Issue 9 Pages 640-647
    Published: September 05, 2018
    Released: April 27, 2019
    JOURNALS FREE ACCESS

    Topological phases of matter have been extensively studied both theoretically and experimentally for their characteristic band structures and exotic transport phenomena. Here, we review quantum anomalous Hall effect as one such example from the viewpoint of topological phases and related experimental results. Quantum anomalous Hall effect has been observed in a magnetic topological insulator Cr doped (Bi1-y Sby)2Te3 thin films, where the spontaneous magnetization induces one-dimensional chiral transport at the edge of the sample. Recent experiments have demonstrated the existence of the chiral edge conduction also along the magnetic domain wall in the sample. By introducing Landauer Büttiker formula, the one-to-one correspondence between the fabricated domain wall and the chiral edge conduction was confirmed. This enables us to construct reconfigurable dissipationless circuit with the control of the domain structure.

    Download PDF (3573K)
  • Naoki Tamaoki, Nobutoshi Aoki, Hideaki Aochi
    Type: Reviews
    2018 Volume 73 Issue 9 Pages 648-657
    Published: September 05, 2018
    Released: April 27, 2019
    JOURNALS FREE ACCESS

    Flash memory with NAND structure (NAND flash memory) is widely used for mobile devices, cell phones, PC’s, and for storage devices in the internet-data-center recently. Conventional two-dimensional (2D) NAND flash memory has serious problems to realize the shrinkage of cell size beyond the 15 nm generation. In order to overcome the problems, two novel nano-technologies, namely Punch & Plug process and BiCS FLASH, have been developed. These innovations have resulted in commercially viable 3D flash memory, providing key technologies for fast, low-energy consumption and high-density memory devices. In this review, we discuss this state-of-the-art 3D flash memory technology.

    Download PDF (5166K)
Researches
  • Tomohiro Tamaya
    Type: Researches
    2018 Volume 73 Issue 9 Pages 658-663
    Published: September 05, 2018
    Released: April 27, 2019
    JOURNALS FREE ACCESS

    We theoretically investigate mechanisms of high-order harmonic generation (HHG) in solids. A new theoretical framework presented here holds legitimacy of Bloch theorem even under an influence of the high-intensity electric field. Our theoretical framework shows the nonadiabatic processes, namely, AC Zener tunneling and semimetallization of semiconductors, are key factors for non-perturbative mechanisms of HHG. These mechanisms are classified by the field intensity with respect to the band gap energy and could be understood by an extended simple man model based on the analogy between tunnel ionization in gaseous media and Zener tunneling in semiconductors. These conclusions would stimulate universal understandings of HHG mechanisms in both atomic and solid cases.

    Download PDF (1633K)
Crossroad
feedback
Top