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Neutrino Shadow and Explosion Mechanism of a Gamma-ray Burst
Rohta Takahashi,Shigehiro Nagataki 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4
Energy deposition due to neutrino pair annihilation around a neutrino-dominated accretion °ow (NDAF) and a black hole is one of the most signi.cant energy sources of a gamma-ray burst(GRB). We calculate the energy deposition rate (EDR) in a hyperaccreting disk around a Kerr black hole by solving the 3D general relativistic radiative transfer equations for neutrinos. We obtain the following results: (i) Most of the neutrinos comes from just outside the marginally bound orbit of neutrino, which means that light-bending eects should be included and 3D radiative transfer calculations are essential. (ii) The total EDR can be changed by 2 { 3 orders if the neutrino temperature changes by only a factor of 2, which means that the general relativistic calculation of neutrino emission processes in the ergosphere is very important. (iii) The local EDR can be increased by the black hole's rotation, even in the case when the rotational energy of the black hole cannot be eectively extracted.
High Energy Neutrino Burst under the Internal Shock Model of Gamma-ray Bursts
Kohta Murase,Shigehiro Nagataki 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4
We calculate the proton cooling e±ciency including pion-multiplicity, and proton-inelasticity in photomeson production under the internal shock model of gamma-ray bursts (GRBs) by using the simulation kit GEANT4. We con.rm the validity of analytic approximate treatments based on GRB .ducial parameter sets, but also .nd that the eects of multiplicity and high inelasticity can be important for both proton cooling and the resulting spectra in some cases. We can estimate the maximum energy of accelerated protons in GRBs by considering various cooling processes. Using the obtained results, we can evaluate the neutrino °ux from one burst and a diuse neutrino background more quantitatively than past works. We assume that the GRB rate traces the star formation rate to obtain the diuse neutrino background. We also take into account the cooling processes of pions and muons, which are crucial to the resulting neutrino spectra. We introduce the nonthermal baryon-loading factor, rather than assume that GRBs are the main sources of ultra-high-enegy-cosmic-rays (UHECRs). We .nd that the obtained neutrino background can be comparable with the prediction of Waxman & Bahcall, although our ground in the estimation is dierent from theirs. This means su±cient photon density and accelerated protons may lead to the higher neutrino °ux, which may be di±cult to achieve. We study various parameters because there are many parameters in the model. The detection of high energy neutrinos from GRBs will provide a piece of strong evidences that protons are accelerated to very high energy in GRBs. Furthermore, the observations of a neutrino background has a possibility for not only testing the internal shock model of GRBs but also giving us infor- mation about the parameters in the model and about whether GRBs are sources of UHECRs or not.G
플라이 애쉬 및 고로수쇄(高爐水碎)슬래그를 혼화(混和)한 콘크리트의 중성화(中性化)에 관한 연구(?究)
나가타키 시게요시,김은겸,오가 히로유키,Nagataki, Shigeyoshi,Kim, Eun Kyum,Ohga, Hiroyuki 대한토목학회 1987 대한토목학회논문집 Vol.7 No.3
콘크리트의 중성화(中性化)는 일종의 화학적(化學的) 반응(反應)이며, 더우기 혼화재(混和材)로서 플라이애쉬와 고로수쇄(高爐水碎)슬래그를 혼화(混和)한 경우에는 그 반응(反應)매카니즘이 매우 복잡하다. 최근에는 콘크리트의 성능(性能)을 개선(改善)시킬 목적으로 시멘트의 일부를 산업부산물(産業副産物)인 플라이애쉬 및 고로수쇄(高爐水碎)슬래그로 혼화(混和)함으로서 이들에 의한 포졸란반응(反應) 및 잠재수경성(潛在水硬性)에 의해 콘크리트의 중성화(中性化)가 촉진되어 콘크리트 속의 철근이 발창(發?)될 우려가 있다고 하는 지적이 계속되어 왔다. 본(本) 연구(硏究)에서는 이상과 같은 관점(觀點)으로부터 포졸란반응(反應) 및 잠재수경성(潛在水硬性)이 콘크리트의 중성화(中性化)에 미치는 영향을 분명히 하기 위하여 콘크리트의 배합조건(配合條件)및 수중양생기간(水中養生期間) 등을 변화시켜 자연환경조건(自然環境條件)과 다른 가혹(苛酷) 환경조건하(環境條件下)에서 촉진중성화실험(促進中性化實驗)을 실시하였다. 또한 이들의 결과를 중성화(中性化)의 조기판정(早期判定)이라는 점에 중시(重視)하여 자연환경하(自然環境下)에서 15년간(年間) 옥내(屋內)에 폭로(曝露)시킨 필자(筆者)들의 연구결과(硏究結果)와도 비교(比較) 검토(檢討)를 하여 압축강도(壓縮强度)에 바탕을 둔 새로운 중성화(中性化) 속도식(速度式)을 제안(提案)하였다. Carbonation of concrete is one type of a chemical process. The reaction mechanism is very complex for the case when low-calcium fly ash and blast furnace slag is added. When fly ash and blast furnace slag is used as an admixture in concrete, they improve compressive strength in the long term, permeability and chemical resistance of concrete by a pozzolanic reaction and latent hydraulic property. On the other hand, the pozzolanic reaction of fly ash and latent hydraulic property of the blast furance slag leads to a reduction of the alkalinity of the concrete. It has been pointed out that this will accelerate the carbonation of the concrete and the corrosion of reinforcement steel embedded in the concrete. In order to clarify the effect of fly ash and blast furance slag on the carbonation of concrete, an accelerated carbonation testing of concrete was carried out by varying the conditions of concrete and the initial curing period in water. The test results of accelerated carbonation were compared to the carbonation test results of concrete stored for 15 years in open air, but protected from rain. As a result, the equation for the rate of carbonation based on compressive strength of concrete was proposed.
Prokhorov, D. A.,Dubois, Y.,Nagataki, S.,Akahori, T.,Yoshikawa, K. Blackwell Publishing Ltd 2011 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.415 No.3
<P><B>ABSTRACT</B></P><P>The Sunyaev–Zel’dovich (hereinafter SZ) effect is a promising tool to derive the gas temperature of galaxy clusters. Approximation of a spherically symmetric gas distribution is usually used to determine the temperature structure of galaxy clusters, but this approximation cannot properly describe merging galaxy clusters. The methods used so far, which do not assume the spherically symmetric distribution, permit us to derive 2D temperature maps of merging galaxy clusters. In this paper, we propose a method to derive the standard temperature deviation and temperature variance along the line of sight, which permits us to analyse the 3D temperature structure of galaxy clusters by means of the thermal SZ effect. We also propose a method to reveal merger shock waves in galaxy clusters by analysing the presence of temperature inhomogeneities along the line of sight.</P>