8,559 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

    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

    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

    Theoretical analysis for critical fluctuations of relaxation trajectory near a saddle-node bifurcation

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    A Langevin equation whose deterministic part undergoes a saddle-node bifurcation is investigated theoretically. It is found that statistical properties of relaxation trajectories in this system exhibit divergent behaviors near a saddle-node bifurcation point in the weak-noise limit, while the final value of the deterministic solution changes discontinuously at the point. A systematic formulation for analyzing a path probability measure is constructed on the basis of a singular perturbation method. In this formulation, the critical nature turns out to originate from the neutrality of exiting time from a saddle-point. The theoretical calculation explains results of numerical simulations.Comment: 18pages, 17figures.The version 2, in which minor errors have been fixed, will be published in Phys. Rev.

    A Field-Induced Re-Entrant Novel Phase and A Ferroelectric-Magnetic Order Coupling in HoMnO3

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    A re-entrant novel phase has been observed in the hexagonal ferroelectric HoMnO3 in the presence of magnetic fields, in the temperature ranges defined by the plateau of the dielectric constant anomaly. The dielectric plateau evolves with fields from a narrow sharp dielectric peak at the Mn-spin rotation transition at 32.8 K in zero magnetic field. Such a field-induced dielectric plateau anomaly appears both in the temperature sweep at a constant field and in the field sweep at a constant temperature without detectable hysteresis. This is attributed to the indirect coupling between the ferroelectric and antiferromagnetic orders, arising from an antiferromagnetic domain wall effect, where the magnetic order parameter of the Mn subsystem has to change sign across the ferroelectric domain wall in the compound, that influences the ferroelectric domains via a local magnetostrictive effect

    Optimal selection and ordering of columns in supersaturated designs

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    Two methods to select columns for assigning factors to work on supersaturated designs are proposed. The focus of interest is the degree of non-orthogonality between the selected columns. One method is the exhaustive enumeration of selections of p columns from all k columns to find the exact optimality, while the other is intended to find an approximate solution by applying techniques used in the corresponding analysis, aiming for ease of use as well as a reduction in the large computing time required for large k with the first method. Numerical illustrations for several typical design matrices reveal that the resulting “approximately” optimal assignments of factors to their columns are exactly optimal for any p. Ordering the columns in E(s2)-optimal designs results in promising new findings including a large number of E(s2)-optimal designs
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