Nobuo Arimoto

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We present a thorough quantitative analysis of the evolution of the colour-magnitude relation for earlytype galaxies in 17 distant clusters with redshifts 0.31 < z < 1.27 using the Kodama & Arimoto (1997) evolutionary model for elliptical galaxies. The model is calibrated to reproduce the colour-magnitude relation for Coma ellipticals at z ∼ 0 and gives the(More)
Observations and theoretical simulations have established a framework for galaxy formation and evolution in the young Universe. Galaxies formed as baryonic gas cooled at the centres of collapsing dark-matter haloes; mergers of haloes and galaxies then led to the hierarchical build-up of galaxy mass. It remains unclear, however, over what timescales galaxies(More)
AKARI (formerly ASTRO-F) is an infrared space telescope designed for an all-sky survey at 10-180 μm, and deep pointed surveys of selected areas at 2-180 μm. The deep pointed surveys with AKARI will significantly advance our understanding of galaxy evolution, the structure formation of the Universe, the nature of the buried AGNs, and the cosmic infrared(More)
We present deep optical imaging observations of 2 square degree area, covered by the Cosmic Evolution Survey (COSMOS), made by the prime-focus camera (Supreme-Cam) on the 8.2 m Subaru Telescope. Observations were done in six broadband [B (4459.78), g0 (4723.18),V (5483.88), r 0 (6213.08), i0 (7640.88), z0 (8855.08)] and one narrowband (NB816) filters. A(More)
Aims. As part of the DART project we have used the ESO/2.2m Wide Field Imager in conjunction with the VLT/FLAMES GIRAFFE spectrograph to study the detailed properties of the resolved stellar population of the Fornax dwarf spheroidal galaxy out to and beyond its tidal radius. Fornax dSph has had a complicated evolution and contains significant numbers of(More)
We present deep, sub-horizontal branch, multi-colour photometry of the Andromeda II dwarf spheroidal (And II dSph) taken with the Subaru Suprime-Cam wide field camera. We identify a red clump population in this galaxy, the first time this feature has been detected in a M31 dSph, which are normally characterized as having no significant intermediate age(More)
We study the chemical and kinematic properties of the first galaxies which formed at a high redshift, using high resolution cosmological numerical simulations, and compared them with the recent observational results for the Sculptor dwarf spheroidal galaxy by Tolstoy et al., who found two distinct stellar populations: the lower metallicity stars are more(More)
We have obtained new deep optical and near-infrared images of the field of the radio-loud quasar 1335.8+2834 at z = 1.086 where an excess in the surface number density of galaxies was reported by Hutchings et al. [AJ, 106, 1324] from optical data. We found a significant clustering of objects with very red optical-near infrared colors, 4 ∼< R−K ∼< 6 and 3 ∼<(More)