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