9,442 research outputs found
Assembly Bias and Splashback in Galaxy Clusters
We use publicly available data for the Millennium Simulation to explore the
implications of the recent detection of assembly bias and splashback signatures
in a large sample of galaxy clusters. These were identified in the SDSS/DR8
photometric data by the redMaPPer algorithm and split into high- and
low-concentration subsamples based on the projected positions of cluster
members. We use simplified versions of these procedures to build cluster
samples of similar size from the simulation data. These match the observed
samples quite well and show similar assembly bias and splashback signals.
Previous theoretical work has found the logarithmic slope of halo density
profiles to have a well-defined minimum whose depth decreases and whose radius
increases with halo concentration. Projected profiles for the observed and
simulated cluster samples show trends with concentration which are opposite to
these predictions. In addition, for high-concentration clusters the minimum
slope occurs at significantly smaller radius than predicted. We show that these
discrepancies all reflect confusion between splashback features and features
imposed on the profiles by the cluster identification and concentration
estimation procedures. The strong apparent assembly bias is not reflected in
the three-dimensional distribution of matter around clusters. Rather it is a
consequence of the preferential contamination of low-concentration clusters by
foreground or background groups.Comment: 17 pages, 16 figures, 3 tables, accepted versio
Pairing of a harmonically trapped fermionic Tonks-Girardeau gas
The fermionic Tonks-Girardeau (FTG) gas is a one-dimensional spin-polarized
Fermi gas with infinitely strong attractive zero-range odd-wave interactions,
arising from a confinement-induced resonance reachable via a three-dimensional
p-wave Feshbach resonance. We investigate the off-diagonal long-range order
(ODLRO) of the FTG gas subjected to a longitudinal harmonic confinement by
analyzing the two-particle reduced density matrix for which we derive a
closed-form expression. Using a variational approach and numerical
diagonalization we find that the largest eigenvalue of the two-body density
matrix is of order N/2, where N is the total particle number, and hence a
partial ODLRO is present for a FTG gas in the trap.Comment: 4 pages, 3 figures, revtex
Fabrication of thick structures by sputtering
Deposit, 5500-gram of Cu-0.15 wt % Zr alloy, sputtered onto copper cylinder to average thickness of 12.29 mm. Structure was achieved with high-rate sputter deposition for about 100 hours total sputtering time. Material had twice the strength of unsputtered material at temperatures to 723 K and equivalent strength at nearly 873 K
Low-density, one-dimensional quantum gases in a split trap
We investigate degenerate quantum gases in one dimension trapped in a
harmonic potential that is split in the centre by a pointlike potential. Since
the single particle eigenfunctions of such a system are known for all strengths
of the central potential, the dynamics for non-interacting fermionic gases and
low-density, strongly interacting bosonic gases can be investigated exactly
using the Fermi-Bose mapping theorem. We calculate the exact many-particle
ground-state wave-functions for both particle species, investigate soliton-like
solutions, and compare the bosonic system to the well-known physics of Bose
gases described by the Gross-Pitaevskii equation. We also address the
experimentally important questions of creation and detection of such states.Comment: 7 pages, 5 figure
Local simulation of singlet statistics for restricted set of measurement
The essence of Bell's theorem is that, in general, quantum statistics cannot
be reproduced by local hidden variable (LHV) model. This impossibility is
strongly manifested while analyzing the singlet state statistics for Bell-CHSH
violations. In this work, we provide various subsets of two outcome POVMs for
which a local hidden variable model can be constructed for singlet state.Comment: 2 column, 5 pages, 4 figures, new references, abstract modified,
accepted in JP
Political Competence, Political Trust, and Action Orientations of University Students
Compared to mass publics in other nations, a relatively large number of Americans believe that they are politically competent—that they are able to influence political affairs. And yet, over the past several years we have witnessed the estrangement of substantial portions of the American citizenry from the political system—an estrangement accompanied by an increase in popular distrust of government
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