7,345 research outputs found
Structural and dynamical uncertainties in modeling axisymmetric elliptical galaxies
Quantitative dynamical models of galaxies require deprojecting the observed
surface brightness to determine the luminosity density of the galaxy. Existing
deprojection methods for axisymmetric galaxies assume that a unique
deprojection exists for any given inclination, even though the projected
density is known to be degenerate to the addition of "konus densities" that are
invisible in projection. We develop a deprojection method based on linear
regularization that can explore the range of luminosity densities statistically
consistent with an observed surface brightness distribution. The luminosity
density is poorly constrained at modest inclinations (i > ~30 deg), even in the
limit of vanishing observational errors. In constant mass-to-light ratio,
axisymmetric, two-integral dynamical models, the uncertainties in the
luminosity density result in large uncertainties in the meridional plane
velocities. However, the projected line-of-sight velocities show variations
comparable to current typical observational uncertainties.Comment: 20 pages, 8 Postscript figures, LaTeX, aaspp4.sty, submitted to
MNRAS; paper w/figs (600 kb) also available at
http://cfa-www.harvard.edu/~romanow/ell.mn.ps.gz GIF-format figures replaced
by PostScrip
The adoption of the European System of Accounts 1995 framework in the national accounts of Malta
The release of ESA 1995 GDP data for Malta has ushered in great changes in the way in which the Maltese economy can be analysed. Indicators computed from the new national accounts reveal that the Maltese economy has achieved a relatively high degree of convergence with the European average, especially when compared with other new Member States. However some industries which are less subject to competitive pressures under-perform compared with their European counterparts, while employment rates remain very low.national accounts, productivity, sectoral analysis
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