2,757 research outputs found
A Deep Radio Survey of Abell 2125 III: The Cluster Core - Merging and Stripping
We use radio, near-IR, optical, and X-ray observations to examine dynamic
processes in the central region of Abell 2125. In addition to the central
triple, including members of both major dynamical subsystems identified from a
redshift survey, this region features a galaxy showing strong evidence for
ongoing gas stripping during a high-velocity passage through the gas in the
cluster core. The disk galaxy C153 exhibits a plume stretching toward the
cluster center seen in soft X-rays by Chandra, parts of which are also seen in
[O II] emission and near-UV continuum light. HST imaging shows a distorted
disk, with star-forming knots asymmetrically distributed and remnant spiral
structure possibly defined by dust lanes. The stars and ionized gas in its disk
are kinematically decoupled, demonstrating that pressure stripping must be
important, and that tidal disruption is not the only mechanism at work.
Comparison of the gas properties seen in the X-ray and optical data on the
plume highlight significant features of the history of stripped gas in the
intracluster medium. The nucleus of C153 also hosts an AGN, shown by the weak
and distorted extended radio emission and a radio compact core. The unusual
strength of the stripping signatures in this instance is likely related to the
high relative velocity of the galaxy with respect to the intracluster medium,
during a cluster/cluster merger, and its passage very near the core of the
cluster. Another sign of recent dynamical events is diffuse starlight
asymmetrically placed about the central triple in a cD envelope. Transient and
extreme dynamical events as seen in Abell 2125 may be important drivers of
galaxy evolution in the cores of rich clusters.Comment: 36 pages, 16 figures, accepted AJ, paper with full resolution figures
is available at http:www.aoc.nrao.edu/~fowen/papers/a2125/a2125paper3.ps.g
Bitangents of tropical plane quartic curves
We study smooth tropical plane quartic curves and show that they satisfy certain properties analogous to (but also different from) smooth plane quartics in algebraic geometry. For example, we show that every such curve admits either infinitely many or exactly 7 bitangent lines. We also prove that a smooth tropical plane quartic curve cannot be hyperelliptic.PostprintPeer reviewe
Del Pezzo surfaces with 1/3(1,1) points
We classify del Pezzo surfaces with 1/3(1,1) points in 29 qG-deformation
families grouped into six unprojection cascades (this overlaps with work of
Fujita and Yasutake), we tabulate their biregular invariants, we give good
model constructions for surfaces in all families as degeneracy loci in rep
quotient varieties and we prove that precisely 26 families admit
qG-degenerations to toric surfaces. This work is part of a program to study
mirror symmetry for orbifold del Pezzo surfaces.Comment: 42 pages. v2: model construction added of last remaining surface,
minor corrections, minor changes to presentation, references adde
A Deep Radio Survey of Abell 2125 II: Accelerated Galaxy Evolution during a Cluster-Cluster Merger
Using our extensive radio, optical, near-IR and X-ray imaging and
spectroscopy, we consider the reason for the unusually large number of radio
detected galaxies, mostly found outside the cluster core, in Abell 2125
(z=0.2465, richness class 4). With 20-cm VLA data, we detect continuum emission
from 90 cluster members. The multiwavelength properties of these galaxies
suggest that most of the radio emission is due to an enhanced star-formation
rate. The dynamical study of Miller et al (2004) suggests that Abell 2125 is
undergoing a major cluster-cluster merger, with our view within 30 degrees of
the merger axis and within 0.2 Gyr of core passage. The combination of
projection effects and the physical processes at work during this special time
in the cluster's evolution seem likely to be responsible for the unusual level
of activity we see in the cluster. We argue that tidal effects on individual
cluster members, often far from the cluster core, are responsible for the
increased star formation. Our results are consistent with the idea that disk
galaxies during this phase of a cluster's evolution undergo rapid evolution,
through a burst of star formation, on their way to becoming S0's.Comment: 53 pages, 12 figures, accepted AJ, paper with full resolution figures
is available at http:www.aoc.nrao.edu/~fowen/papers/a2125/a2125paper2.ps.g
Influence of the cavity on the low-temperature photoluminescence of SiGe/Si multiquantum wells grown on a silicon-on-insulator substrate
The influences of the cavity on the low-temperature photoluminescence of Si0.59Ge0.41/Si multiquantum wells grown on silicon-on-insulator substrates are discussed. The positions of the modulated photoluminescence (PL) peaks not only relate to the nature of SiGe/Si multiquantum wells, but also relate to the characteristic of the cavity. With increasing temperature, a redshift of the modulated PL peak originating from the thermo-optical effect of the cavity is observed. (c) 2006 American Institute of Physics. (DOI:10.1063/1.2187433
Spinless composite fermions in an ultrahigh-quality strained Ge quantum well
We report on an observation of a fractional quantum Hall effect in an ultrahigh-quality two-dimensional hole gas hosted in a strained Ge quantum well. The Hall resistance reveals precisely quantized plateaus and vanishing longitudinal resistance at filling factors ν=2/3,4/3, and 5/3. From the temperature dependence around ν=3/2 we obtain the composite fermion mass of m☆≈0.4me, where me is the mass of a free electron. Owing to large Zeeman energy, all observed states are spin polarized and can be described in terms of spinless composite fermions
What Makes Theatrical Performances Successful in China's Tourism Industry?
This study aims to explore the factors affecting the success of a popular tourist product, namely, theatrical performance, within the context of China's tourism industry and develop a model based on previously successful productions. Using qualitative software, 22 Chinese-language articles on theatrical performances are analyzed to generate a list of success factors, classified as internal and external. The internal factors are storyline and performing, market positioning and marketing strategy, investment and financial support, operation and management, performing team, outdoor venue, indoor/outdoor stage supporting facilities, continuous improvement, and production team. The external factors are collaboration between cultural industries and local tourism, government support, privatization, and social and cultural effect. This study also provides suggestions for the future development of theatrical performances in China
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