59,699 research outputs found
Interplay between the ionic and electronic density profiles in liquid metal surfaces
First principles molecular dynamics simulations have been performed for the
liquid-vapor interfaces of liquid Li, Mg, Al and Si. We analize the oscillatory
ionic and valence electronic density profiles obtained, their wavelengths and
the mechanisms behind their relative phase-shift.Comment: Accepted for publication in Journal of Chemical Physic
R-Band Imaging of Fields Around 1<z<2 Radiogalaxies
We have taken deep -band images of fields around five radiogalaxies:
0956+47, 1217+36, 3C256, 3C324 and 3C294 with . 0956+47 is found to
show a double nucleus. Our data on 1217+36 suggest the revision of its
classification as a radiogalaxy. We found a statistically significant excess of
bright () galaxies on scales of 2 arcmin around the radiogalaxies
(which have ) in our sample. The excess has been determined
empirically to be at level. It is remarkable that this excess
is not present for galaxies within the same area, suggesting that
the excess is not physically associated to the galaxies but due to intervening
groups and then related to gravitational lensing.Comment: 20 pages, uuencoded compressed PostScript including tables. Figures
available upon request. To appear in the March 1995 issue of The Astronomical
Journa
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Constraining our Universe with X-ray & Optical Cluster Data
We have used recent X-ray and optical data in order to impose some
constraints on the cosmology and cluster scaling relations. Generically two
kind of hypotheses define our model. First we consider that the cluster
population is well described by the standard Press-Schechter (PS) formalism,
and second, these clusters are supposed to follow scaling relations with mass:
Temperature-Mass (T-M) and X-ray Luminosity-Mass (L_x - M). As a difference
with many other authors we do not assume specific scaling relations to model
cluster properties such as the usual virial relation or one observational
determination of the relation. Instead we consider general free
parameter scaling relations. With the previous model (PS plus scalings) we fit
our free parameters to several X-ray and optical data with the advantage over
many other works that we consider all the data sets at the same time. This
prevents us from being inconsistent with some of the available observations.
Among other interesting conclusions, we find that only low-density universes
are compatible with all the data considered and that the degeneracy between
and is broken. Also we obtain interesting limits on the
parameters characterizing the scaling relations.Comment: 11 pages, 7 figures. MNRAS accepted versio
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