3,249 research outputs found
A Redshift Survey of the Strong Lensing Cluster Abell 383
Abell 383 is a famous rich cluster (z = 0.1887) imaged extensively as a basis
for intensive strong and weak lensing studies. Nonetheless there are few
spectroscopic observations. We enable dynamical analyses by measuring 2360 new
redshifts for galaxies with r and within 50 of the
BCG (Brightest Cluster Galaxy: R.A., Decl). We apply the caustic technique to identify 275 cluster
members within 7 Mpc of the hierarchical cluster center. The BCG lies
within km s and 21 kpc of the hierarchical
cluster center; the velocity dispersion profile of the BCG appears to be an
extension of the velocity dispersion profile based on cluster members. The
distribution of cluster members on the sky corresponds impressively with the
weak lensing contours of Okabe et al. (2010) especially when the impact of
foreground and background structure is included. The values of R =
Mpc and M = M obtained by application of the caustic technique agree well
with recent completely independent lensing measures. The caustic estimate
extends direct measurement of the cluster mass profile to a radius of Mpc.Comment: 29 pages, 9 figures, ApJ accepte
Quantum Dot Potentials: Symanzik Scaling, Resurgent Expansions and Quantum Dynamics
This article is concerned with a special class of the ``double-well-like''
potentials that occur naturally in the analysis of finite quantum systems.
Special attention is paid, in particular, to the so-called Fokker-Planck
potential, which has a particular property: the perturbation series for the
ground-state energy vanishes to all orders in the coupling parameter, but the
actual ground-state energy is positive and dominated by instanton
configurations of the form exp(-a/g), where a is the instanton action. The
instanton effects are most naturally taken into account within the modified
Bohr-Sommerfeld quantization conditions whose expansion leads to the
generalized perturbative expansions (so-called resurgent expansions) for the
energy values of the Fokker-Planck potential. Until now, these resurgent
expansions have been mainly applied for small values of coupling parameter g,
while much less attention has been paid to the strong-coupling regime. In this
contribution, we compare the energy values, obtained by directly resumming
generalized Bohr-Sommerfeld quantization conditions, to the strong-coupling
expansion, for which we determine the first few expansion coefficients in
powers of g^(-2/3). Detailed calculations are performed for a wide range of
coupling parameters g and indicate a considerable overlap between the regions
of validity of the weak-coupling resurgent series and of the strong-coupling
expansion. Apart from the analysis of the energy spectrum of the Fokker-Planck
Hamiltonian, we also briefly discuss the computation of its eigenfunctions.
These eigenfunctions may be utilized for the numerical integration of the
(single-particle) time-dependent Schroedinger equation and, hence, for studying
the dynamical evolution of the wavepackets in the double-well-like potentials.Comment: 13 pages; RevTe
Overview of the MEDLI Project
The Mars Science Laboratory Entry, Descent, and Landing Instrumentation (MEDLI) Project's objectives are to measure aerothermal environments, sub-surface heatshield material response, vehicle orientation, and atmospheric density for the atmospheric entry and descent phases of the Mars Science Laboratory (MSL) entry vehicle. The flight science objectives of MEDLI directly address the largest uncertainties in the ability to design and validate a robust Mars entry system, including aerothermal, aerodynamic and atmosphere models, and thermal protection system (TPS) design. The instrumentation suite will be installed in the heatshield of the MSL entry vehicle. The acquired data will support future Mars entry and aerocapture missions by providing measured atmospheric data to validate Mars atmosphere models and clarify the design margins for future Mars missions. MEDLI thermocouple and recession sensor data will significantly improve the understanding of aeroheating and TPS performance uncertainties for future missions. MEDLI pressure data will permit more accurate trajectory reconstruction, as well as separation of aerodynamic and atmospheric uncertainties in the hypersonic and supersonic regimes. This paper provides an overview of the project including the instrumentation design, system architecture, and expected measurement response
The chemical evolution of star-forming galaxies over the last 11 billion years
We calculate the stellar mass-metallicity relation at five epochs ranging to z ∼ 2.3. We quantify evolution in the shape of the mass-metallicity relation as a function of redshift; the mass-metallicity relation flattens at late times. There is an empir
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