5,003 research outputs found

    Luminosity Dependent Evolution of Lyman Break Galaxies from redshift 5 to 3

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    In this contribution we briefly describe our recent results on the properties of Lyman break galaxies at z~5 obtained from deep and wide blank field surveys using Subaru telescope, and through the comparison with samples at lower redshift ranges we discuss the evolution of star-forming galaxies in the early universe.Comment: 2 pages, 1 figure, for the proceedings of the IAU Symposium 235, Galaxies Across the Hubble Time, J. Palous & F. Combes, ed

    Lyman Break Galaxies at z5z\sim5: Rest-Frame UV Spectra

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    We report initial results for spectroscopic observations of candidates of Lyman Break Galaxies (LBGs) at z5z\sim5 in a region centered on the Hubble Deep Field-North by using the Faint Object Camera and Spectrograph attached to the Subaru Telescope. Eight objects with IC25.0I_C\leq25.0 mag, including one AGN, are confirmed to be at 4.5<z<5.24.5<z<5.2. The rest-frame UV spectra of seven LBGs commonly show no or weak Lyalpha emission line (rest-frame equivalent width of 0-10\AA) and relatively strong low-ionization interstellar metal absorption lines of SiII λ\lambda1260, OI+SiII λ\lambda1303, and CII λ\lambda1334 (mean rest-frame equivalent widths of them are 1.25.1-1.2 \sim -5.1 \AA). These properties are significantly different from those of the mean rest-frame UV spectrum of LBGs at z3z\sim3, but are quite similar to those of subgroups of LBGs at z3z\sim3 with no or weak Lyalpha emission. The weakness of Lyalpha emission and strong low-ionization interstellar metal absorption lines may indicate that these LBGs at z5z\sim5 are chemically evolved to some degree and have a dusty environment. Since the fraction of such LBGs at z5z\sim5 in our sample is larger than that at z3z\sim3, we may witness some sign of evolution of LBGs from z5z\sim5 to z3z\sim3, though the present sample size is very small. It is also possible, however, that the brighter LBGs tend to show no or weak Lyalpha emission, because our spectroscopic sample is bright (brighter than LL^{\ast}) among LBGs at z5z\sim5. More observations are required to establish spectroscopic nature of LBGs at z5z\sim5.Comment: 16 pages, 3 figures, accepted by Ap

    Ingredients of nuclear matrix element for two-neutrino double-beta decay of 48Ca

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    Large-scale shell model calculations including two major shells are carried out, and the ingredients of nuclear matrix element for two-neutrino double beta decay are investigated. Based on the comparison between the shell model calculations accounting only for one major shell (pfpf-shell) and those for two major shells (sdpfsdpf-shell), the effect due to the excitation across the two major shells is quantitatively evaluated.Comment: To appear in J. Phys. Soc. Conf. Proc. (ARIS2014); for ver.2, Fig.1 is revise

    Ferroan relict minerals in the Tottuki and South Pole micrometeorites.

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    第2回極域科学シンポジウム/第34回南極隕石シンポジウム 11月17日(木) 国立国語研究所 2階講

    Singular perturbation near mode-coupling transition

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    We study the simplest mode-coupling equation which describes the time correlation function of the spherical p-spin glass model. We formulate a systematic perturbation theory near the mode-coupling transition point by introducing multiple time scales. In this formulation, the invariance with respect to the dilatation of time in a late stage yields an arbitrary constant in a leading order expression of the solution. The value of this constant is determined by a solvability condition associated with a linear singular equation for perturbative corrections in the late stage. The solution thus constructed provides exactly the alpha-relaxation time.Comment: 15 pages, 4 figure

    Pickoff and spin-conversion quenchings of ortho-positronium in oxygen

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    The quenching processes of the thermalized ortho-positronium(o-Ps) on an oxygen molecule have been studied by the positron annihilation age-momentum correlation techinique(AMOC). The Doppler broadening spectrum of the 511 keV gamma-rays from the 2gamma annihilation of o-Ps in O_2 has been measured as a function of the o-Ps age. The rate of the quenching, consisting of the pickoff and the spin-conversion, is estimated from the positron lifetime spectrum. The ratio of the pickoff quenching rate to the spin-conversion rate is deduced from the Doppler broadening of the 511 keV gamma-rays from the annihilation of the o-Ps. The pickoff parameter ^1Z_eff, the effective number of the electrons per molecule which contribute to the pickoff quenching, for O_2 is determined to be 0.6 +- 0.4. The cross-section for the elastic spin-conversion quenching is determined to be (1.16 +- 0.01) * 10^{-19} cm^2.Comment: 4 pages with 5 eps figures, LaTeX2e(revtex4
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