Institution
Aoyama Gakuin University
Education•Tokyo, Japan•
About: Aoyama Gakuin University is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Superconductivity & Thin film. The organization has 3494 authors who have published 6419 publications receiving 115648 citations. The organization is also known as: Aoyama gakuin daigaku.
Papers published on a yearly basis
Papers
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TL;DR: In this article, the authors analyzed the Hitomi first-light observation of the Perseus cluster and found no anomalously high fluxes of the nearby faint K line or the Ar satellite line that were proposed as explanations for the earlier 3.5 keV detections.
Abstract: High-resolution X-ray spectroscopy with Hitomi was expected to resolve the origin of the faint unidentified $E\approx 3.5\,\mathrm{keV}$ emission line reported in several low-resolution studies of various massive systems, such as galaxies and clusters, including the Perseus cluster. We have analyzed the Hitomi first-light observation of the Perseus cluster. The emission line expected for Perseus based on the XMM-Newton signal from the large cluster sample under the dark matter decay scenario is too faint to be detectable in the Hitomi data. However, the previously reported 3.5 keV flux from Perseus was anomalously high compared to the sample-based prediction. We find no unidentified line at the reported high flux level. Taking into account the XMM measurement uncertainties for this region, the inconsistency with Hitomi is at a 99% significance for a broad dark matter line and at 99.7% for a narrow line from the gas. We do not find anomalously high fluxes of the nearby faint K line or the Ar satellite line that were proposed as explanations for the earlier 3.5 keV detections. We do find a hint of a broad excess near the energies of high-n transitions of S xvi ($E\simeq 3.44\,\mathrm{keV}$ rest-frame)—a possible signature of charge exchange in the molecular nebula and another proposed explanation for the unidentified line. While its energy is consistent with XMM pn detections, it is unlikely to explain the MOS signal. A confirmation of this interesting feature has to wait for a more sensitive observation with a future calorimeter experiment.
136 citations
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TL;DR: The Next Generation of Physics, Spun from Universality and Emergence (NGPE) as mentioned in this paper ) is a project of the Global COE Program for the next generation of physics.
Abstract: Japan. Ministry of Education, Culture, Sports, Science and Technology (Grants-in-Aid for Scientific Research 20540230, Global COE Program “The Next Generation of Physics, Spun from Universality and Emergence”)
135 citations
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TL;DR: The critical rheology of sheared frictional granular materials near jamming transition is numerically investigated and it is confirmed that there exists a true critical density which characterizes the onset of the yield stress and two fictitious critical densities which characterize the scaling laws of rheological properties.
Abstract: The critical rheology of sheared frictional granular materials near jamming transition is numerically investigated. It is confirmed that there exists a true critical density which characterizes the onset of the yield stress and two fictitious critical densities which characterize the scaling laws of rheological properties. We find the existence of a hysteresis loop between two of the critical densities for each friction coefficient. It is noteworthy that the critical scaling law for frictionless jamming transition seems to be still valid even for frictional jamming despite using fictitious critical density values.
135 citations
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Los Alamos National Laboratory1, Tokyo Institute of Technology2, University of Chicago3, Massachusetts Institute of Technology4, Aoyama Gakuin University5, National Space Development Agency of Japan6, New Mexico State University7, University of California, Berkeley8, Centre national de la recherche scientifique9, University of California, Santa Cruz10, Goddard Space Flight Center11, National Institute for Space Research12, Tata Institute of Fundamental Research13
TL;DR: In this paper, the authors show that the properties of X-ray flash XRF 020903 are consistent with the relation between the fluences S(7-30 keV) and S(30-400 keV), found by Barraud et al. for GRBs.
Abstract: We report High Energy Transient Explorer 2 (HETE-2) Wide Field X-Ray Monitor/French Gamma Telescope observations of the X-ray flash XRF 020903. This event was extremely soft: the ratio log(SX/Sγ) = 0.7, where SX and Sγ are the fluences in the 2-30 and 30-400 keV energy bands, is the most extreme value observed so far by HETE-2. In addition, the spectrum has an observed peak energy of E < 5.0 keV (99.7% probability upper limit), and no photons were detected above ~10 keV. The burst is shorter at higher energies, which is similar to the behavior of long gamma-ray bursts (GRBs). We consider the possibility that the burst lies at very high redshift and that the low value of E is due to the cosmological redshift, and show that this is very unlikely. We find that the properties of XRF 020903 are consistent with the relation between the fluences S(7-30 keV) and S(30-400 keV), found by Barraud et al. for GRBs and X-ray-rich GRBs, and are consistent with the extension by a decade of the hardness-intensity correlation found by the same authors. Assuming that XRF 020903 lies at a redshift z = 0.25, as implied by the host galaxy of the candidate optical and radio afterglows of this burst, we find that the properties of XRF 020903 are consistent with an extension by a factor ~300 of the relation between the isotropic-equivalent energy Eiso and the peak Epeak of the νFν spectrum (in the source frame of the burst) found by Amati et al. for GRBs. The results presented in this paper therefore provide evidence that X-ray flashes (XRFs), X-ray-rich GRBs, and GRBs form a continuum and are a single phenomenon. The results also impose strong constraints on models of XRFs and X-ray-rich GRBs.
134 citations
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Harvard University1, National Radio Astronomy Observatory2, University of Virginia3, University of California, Berkeley4, Rutgers University5, Stockholm University6, Goddard Space Flight Center7, University of Arizona8, University of Alabama in Huntsville9, INAF10, Hiroshima University11, Johns Hopkins University Applied Physics Laboratory12, University of Tokyo13, Los Alamos National Laboratory14, Saitama University15, Aoyama Gakuin University16
TL;DR: In this paper, a generalized analytic formalism for the inverse Compton X-ray emission from hydrogen-poor supernovae is presented and applied to SN 2011fe using Swift X-Ray Telescope (XRT), UVOT, and Chandra observations.
Abstract: We present a generalized analytic formalism for the inverse Compton X-ray emission from hydrogen-poor supernovae and apply this framework to SN 2011fe using Swift X-Ray Telescope (XRT), UVOT, and Chandra observations. We characterize the optical properties of SN 2011fe in the Swift bands and find them to be broadly consistent with a normal SN Ia, however, no X-ray source is detected by either XRT or Chandra. We constrain the progenitor system mass-loss rate (3σ c.l.) for wind velocity vw = 100 km s–1. Our result rules out symbiotic binary progenitors for SN 2011fe and argues against Roche lobe overflowing subgiants and main-sequence secondary stars if 1% of the transferred mass is lost at the Lagrangian points. Regardless of the density profile, the X-ray non-detections are suggestive of a clean environment (n CSM < 150 cm–3) for 2 × 1015 R 5 × 1016 cm around the progenitor site. This is either consistent with the bulk of material being confined within the binary system or with a significant delay between mass loss and supernova explosion. We furthermore combine X-ray and radio limits from Chomiuk et al. to constrain the post-shock energy density in magnetic fields. Finally, we searched for the shock breakout pulse using gamma-ray observations from the Interplanetary Network and find no compelling evidence for a supernova-associated burst. Based on the compact radius of the progenitor star we estimate that the shock breakout pulse was likely not detectable by current satellites.
134 citations
Authors
Showing all 3525 results
Name | H-index | Papers | Citations |
---|---|---|---|
Katsuhiko Mikoshiba | 120 | 866 | 62394 |
Tadayuki Takahashi | 112 | 932 | 57501 |
Takaaki Tanaka | 105 | 321 | 41804 |
Yasunobu Uchiyama | 105 | 373 | 39610 |
Sang-Wook Cheong | 79 | 645 | 37338 |
T. Sakamoto | 65 | 523 | 17443 |
Yutaka Saito | 64 | 516 | 17729 |
Nakao Iwata | 64 | 548 | 24469 |
Ryo Yamazaki | 59 | 317 | 16782 |
Takeshi Go Tsuru | 59 | 405 | 13507 |
Masahiro Yamashita | 58 | 573 | 15371 |
Toshio Yamagishi | 52 | 152 | 12998 |
Jun Akimitsu | 52 | 608 | 11035 |
Kazutaka Yamaoka | 51 | 372 | 11846 |
Aya Bamba | 50 | 306 | 13253 |