808 research outputs found

    Origins of the ALMA Project in the scientific visions of the North American, European, and Japanese astronomical communities

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    ALMA is a worldwide project, the synthesis of early visions of astronomers in its three partner communities, Europe, North America, and Japan. The evolution of these concepts and their eventual merger into ALMA are discussed, setting the background for the papers which follow on the scientific requirements and expected performance of ALMA for extra-galactic, galactic, and solar system research.Comment: 4 pages, including 1 figure; to appear in ESA SP-577, Proceedings of the conference "Dusty and Molecular Universe - A prelude to HERSCHEL AND ALMA", October 25-27, 2004, Pari

    High Redshift HCN Emission: Dense Star-Forming Molecular Gas in IRAS F10214+4724

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    Hydrogen cyanide emission in the J=1-0 transition has been detected at redshift z=2.2858 in IRAS F10214+4724 using the Green Bank Telescope . This is the second detection of HCN emission at high redshift. The large HCN line luminosity in F10214 is similar to that in the Cloverleaf (z=2.6) and the ultra-luminous infrared galaxies Mrk231 and Arp220. This is also true of the ratio of HCN to CO luminosities. The ratio of far-infrared luminosity to HCN luminosity, an indicator of the star formation rate per solar mass of dense gas, follows the correlation found for normal spirals and infrared luminous starburst galaxies. F10214 clearly contains a starburst that contributes, together with its embedded quasar, to its overall infrared luminosity. A new technique for removing spectral baselines in the search for weak, broad emission lines is presented.Comment: 9 pages, 2 figures; accepted ApJ(Letters

    Fermionic superfluidity with positive scattering length

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    Superfluidity in an ultracold Fermi gas is usually associated with either a negative scattering length, or the presence of a two-body bound state. We show that none of these ingredients is necessary to achieve superfluidity. Using a narrow Feshbach resonance with strong repulsive background interactions, the effective interactions can be repulsive for small energies and attractive for energies around the Fermi energy, similar to the effective interactions between electrons in a metallic superconductor. This can result in BCS-type superfluidity while the scattering length is positive.Comment: 6 pages, 3 figures; v2: added references and details energy-dependent interactio

    Kwok-Yung Lo

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    Radio astronomer and physicist Kwok-Yung “Fred” Lo was born on 19 October 1947 in Nanjing, China. The third of six sons, he grew up in Hong Kong, where his father had moved his antique business in 1949 in search of better opportunities. Fred came to the US in 1965 to attend MIT, where he earned his BS in 1969 and a PhD in 1974, both in physics. His thesis, titled “Interstellar microwave radiation and early stellar evolution,” was supervised by radio astronomer Bernard Burke

    VLA Limits for Intermediate Mass Black Holes in Three Globular Clusters

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    The observational evidence for central black holes in globular clusters has been argued extensively, and their existence has important consequences for both the formation and evolution of the cluster. Most of the evidence comes from dynamical arguments, but the interpretation is difficult, given the short relaxation times and old ages of the clusters. One of the most robust signatures for the existence of a black hole is radio and/or X-ray emission. We observed three globular clusters, NGC6093 (M80), NGC6266 (M62), and NGC7078 (M15), with the VLA in the A and C configuration with a 3-sigma noise of 36, 36 and 25 microJy, respectively. We find no statistically-significant evidence for radio emission from the central region for any of the three clusters. NGC6266 shows a 2-sigma detection. It is difficult to infer a mass from these upper limits due to uncertainty about the central gas density, accretion rate, and accretion model.Comment: 5 pages, accepted for publication in the Astronomical Journa
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