5,970 research outputs found

    Tracing Recent Star Formation of Red Early-type Galaxies out to zz \sim 1

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    We study the mid-infrared (IR) excess emission of early-type galaxies (ETGs) on the red-sequence at z<z < 1 using a spectroscopic sample of galaxies in the fields of Great Observatories Origins Deep Survey (GOODS). In the mass-limited sample of 1025 galaxies with MstarM_{star} >> 1010.5^{10.5} MM_{\odot} and 0.4<z<1.050.4<z<1.05, we identify 696 SpitzerSpitzer 24 μ\mum detected (above the 5σ\sigma) galaxies and find them to have a wide range of NUV-rr and rr-[12 μ\mum] colors despite their red optical uru-r colors. Even in the sample of very massive ETGs on the red sequence with MstarM_{star} >> 1011.2^{11.2} MM_{\odot}, more than 18% show excess emission over the photospheric emission in the mid-IR. The combination with the results of red ETGs in the local universe suggests that the recent star formation is not rare among quiescent, red ETGs at least out to z1z \sim 1 if the mid-IR excess emission results from intermediate-age stars or/and from low-level ongoing star formation. Our color-color diagram including near-UV and mid-IR emissions are efficient not only for identifying ETGs with recent star formation, but also for distinguishing quiescent galaxies from dusty star-forming galaxies.Comment: 25 pages, 9 figures, accepted for publication in Ap

    To the Edge of M87 and Beyond: Spectroscopy of Intracluster Globular Clusters and Ultra Compact Dwarfs in the Virgo Cluster

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    We present the results from a wide-field spectroscopic survey of globular clusters (GCs) in the Virgo Cluster. We obtain spectra for 201 GCs and 55 ultracompact dwarfs (UCDs) using the Hectospec on the Multiple Mirror Telescope, and derive their radial velocities. We identify 46 genuine intracluster GCs (IGCs), not associated with any Virgo galaxies, using the 3D GMM test on the spatial and radial velocity distribution.They are located at the projected distance 200 kpc \lesssim R \lesssim 500 kpc from the center of M87. The radial velocity distribution of these IGCs shows two peaks, one at vrv_{\rm r} = 1023 km s1^{-1} associated with the Virgo main body, and another at vrv_{\rm r} = 36 km s1^{-1} associated with the infalling structure. The velocity dispersion of the IGCs in the Virgo main body is σGC\sigma_{\rm{GC}} \sim 314 km s1^{-1}, which is smoothly connected to the velocity dispersion profile of M87 GCs, but much lower than that of dwarf galaxies in the same survey field, σdwarf\sigma_{\rm{dwarf}} \sim 608 km s1^{-1}. The UCDs are more centrally concentrated on massive galaxies, M87, M86, and M84. The radial velocity dispersion of the UCD system is much smaller than that of dwarf galaxies. Our results confirm the large-scale distribution of Virgo IGCs indicated by previous photometric surveys. The color distribution of the confirmed IGCs shows a bimodality similar to that of M87 GCs. This indicates that most IGCs are stripped off from dwarf galaxies and some from massive galaxies in the Virgo.Comment: 19 pages, 20 figures, 8 tables, accepted for publication in Ap

    SUSTAINABLE DEVELOPMENT OF OFFSHORE SOFTWARE OUTSOURCING IN VIETNAM: THE CASE OF FPT SOFTWARE

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    The aims of the paper are to describe the Vietnamese offshore software outsourcing industry and to investigate key success factors of the largest offshore software outsourcing company in Vietnam, FPT Software. Vietnam has taken ICT industry a strategic one for its economic development, and it has been showing high growth in that field. Especially, Vietnam has potential to be successful in offshore software outsourcing, but Vietnam won\u27t be sustainable in this competitive market unless it overcomes several weaknesses. FPT Software as the best achiever so far is a good model for Vietnamese software companies. The key success factors of sustainable development in FPT Software are found in good managerial practices, application of international quality standards for software development, and highly motivated and skilled workforces. Based on the case study, we discuss the sustainability of Vietnam\u27s offshore software outsourcing

    Measuring Vub|V_{ub}| at future B-Factories

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    We calculate the so--called Fermi motion parameter pFp_{_F} of ACCMM model using the variational method in a potential model approach. We also propose hadronic invariant mass distribution as an alternative experimental observable to measure VubV_{ub} at future asymmetric BB factories.Comment: 9 pages (1 fugure not included
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