N Arimoto

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We present the results of a deep, wide-area, optical and near-IR survey of massive high-redshift galaxies. The Prime Focus Camera (Suprime-Cam) on the Subaru telescope was used to obtain BRIz ′ imaging over 2 × 940 arcmin 2 fields, while JK s imaging was provided by the SOFI camera at the New Technology Telescope (NTT) for a subset of the area, partly from(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)
  • G Battaglia, E Tolstoy, A Helmi, M J Irwin, B Letarte, P Jablonka +10 others
  • 2006
Aims. As part of the DART project we have used the ESO/2.2m Wide Field Imager in conjunction with the VLT/FLAMES ⋆ GIRAFFE spec-trograph 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)
  • Amina Helmi, M J Irwin, E Tolstoy, G Battaglia, V Hill, P Jablonka +6 others
  • 2006
As part of the Dwarf galaxies Abundances and Radial-velocities Team (DART) Programme, we have measured the metallicities of a large sample of stars in four nearby dwarf spheroidal galaxies (dSph): Sculptor, Sextans, Fornax and Carina. The low mean metal abundances and the presence of very old stellar populations in these galaxies have supported the view(More)
We derive age-metallicity relations (AMRs) and orbital parameters for the 1658 solar neighbourhood stars to which accurate distances are measured by the HIPPARCOS satellite. The sample stars comprise 1382 thin disc stars, 229 thick disc stars, and 47 halo stars according to their orbital parameters. We find a considerable scatter for thin disc AMR along the(More)
Star formation and chemical enrichment histories of the dwarf spheroidal galaxies (dSphs) Draco, Sextans, and Ursa Minor are investigated by means of chemical evolution models and a simulation code for colour-magnitude diagrams (CMDs). The CMD simulation code is designed to fully consider effects of the chemical evolution on stellar evolution and(More)
  • Alexandre Vazdekis, Harald Kuntschner, Roger L Davies, N Arimoto, O Nakamura, R F Peletier
  • 2001
We explore the origin of the color-magnitude relation (CMR) of early type galaxies in the Virgo cluster using spectra of very high S/N ratio for six elliptical galaxies selected along the CMR. The data are analysed using a new evolutionary stellar population synthesis model to generate galaxy spectra at the resolution given by their velocity dispersions. In(More)
Received ; accepted – 2 – ABSTRACT We derive new spectral Hγ index definitions which are robust age indicators for old and relatively old stellar populations and therefore have great potential for solving the age-metallicity degeneracy of galaxy spectra. To study this feature as a function of age, metallicity and resolution, we have used a new spectral(More)
We present the X-ray properties of the extremely red objects (ERO) population observed by Chandra with three partially overlapping pointings (up to ≈ 90 ks) over an area of ≈ 500 arcmin 2 , down to a 0.5–8 keV flux limit of ≈ 10 −15 erg cm −2 s −1. We selected EROs using a multi-band photometric catalog down to a K S-band magnitude of ≈ 19.3 (Vega system);(More)
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