20 research outputs found
The Mass-Richness Relation of MaxBCG Clusters from Quasar Lensing Magnification using Variability
Accurate measurement of galaxy cluster masses is an essential component not
only in studies of cluster physics, but also for probes of cosmology. However,
different mass measurement techniques frequently yield discrepant results. The
SDSS MaxBCG catalog's mass-richness relation has previously been constrained
using weak lensing shear, Sunyaev-Zeldovich (SZ), and X-ray measurements. The
mass normalization of the clusters as measured by weak lensing shear is >~25%
higher than that measured using SZ and X-ray methods, a difference much larger
than the stated measurement errors in the analyses. We constrain the
mass-richness relation of the MaxBCG galaxy cluster catalog by measuring the
gravitational lensing magnification of type I quasars in the background of the
clusters. The magnification is determined using the quasars' variability and
the correlation between quasars' variability amplitude and intrinsic
luminosity. The mass-richness relation determined through magnification is in
agreement with that measured using shear, confirming that the lensing strength
of the clusters implies a high mass normalization, and that the discrepancy
with other methods is not due to a shear-related systematic measurement error.
We study the dependence of the measured mass normalization on the cluster halo
orientation. As expected, line-of-sight clusters yield a higher normalization;
however, this minority of haloes does not significantly bias the average
mass-richness relation of the catalog.Comment: 9 pages. Accepted for publication in Ap
Probing dynamical symmetry breaking using quantum-entangled photons
We present an input/output analysis of photon-correlation experiments whereby
a quantum mechanically entangled bi-photon state interacts with a material
sample placed in one arm of a Hong-Ou-Mandel (HOM) apparatus. We show that the
output signal contains detailed information about subsequent entanglement with
the microscopic quantum states in the sample. In particular, we apply the
method to an ensemble of emitters interacting with a common photon mode within
the open-system Dicke Model. Our results indicate considerable dynamical
information concerning spontaneous symmetry breaking can be revealed with such
an experimental system
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Andromeda: A Few-body Plane Wave Calculator
At TACCSTER last year, a novel method of ours to solve the 3-body lithium problem was presented. Without finishing, the computation plateaued at -7.3 (of -7.4) Hartree on an L = 67 ^ 9 grid running on a single TACC Lonestar5 node for three months. We have now released a new version of the Andromeda code capable of embarrassingly parallel operations. This improvement followed from a significant speedup of half the process, namely the free and exact creation of the Hamiltonian quantum operators and their operation in Sums of Products form. Even though this does not speed up the vector decomposition process, which is still the rate-limiting step, we can now distribute processing per term-state combination across numerous computational resources to overcome this problem. In particular, any 2-body interaction quantum operator is now a summation of processes defined by separate 1-body matrices for the 2-body diagonal, 1-body diagonal, and off-diagonal aspects of the quantum operation. Thus, every core in a parallel process can individually initialize the Coulombic quantum operator, which allows embarrassingly parallel operations across several state vectors. The current release has integrated the TACC/launcher as a vehicle to handle parallel operations. Digitize your wave function with the most local representation of the plane-wave basis. Tackle strongly correlated problems with a spatial component separated, but fully multi-body, Sums-of-Products representation. Compute 3-body quantum physics with a powerful scripting interface. Discover something
The QUEST Data Processing Software Pipeline
A program that we call the QUEST Data Processing Software Pipeline has been
written to process the large volumes of data produced by the QUEST camera on
the Samuel Oschin Schmidt Telescope at the Palomar Observatory. The program
carries out both aperture and PSF photometry, combines data from different
repeated observations of the same portion of sky, and produces a Master Object
Catalog. A rough calibration of the data is carried out. This program, as well
as the calibration procedures and quality checks on the output are described.Comment: 17 pages, 1 table, 8 figure
Effective Hamiltonian Theory and Its Applications in Quantum Information
This paper presents a useful compact formula for deriving an effective
Hamiltonian describing the time-averaged dynamics of detuned quantum systems.
The formalism also works for ensemble-averaged dynamics of stochastic systems.
To illustrate the technique we give examples involving Raman processes,
Bloch-Siegert shifts and Quantum Logic Gates.Comment: 5 pages, 3 figures, to be published in Canadian Journal of Physic
Blazar Optical Variability in the Palomar-QUEST Survey
We study the ensemble optical variability of 276 FSRQs and 86 BL Lacs in the
Palomar-QUEST Survey with the goal of searching for common fluctuation
properties, examining the range of behavior across the sample, and
characterizing the appearance of blazars in such a survey so that future work
can more easily identify such objects. The survey, which covers 15,000 square
degrees multiple times over 3.5 years, allows for the first ensemble blazar
study of this scale. Variability amplitude distributions are shown for the FSRQ
and BL Lac samples for numerous time lags, and also studied through structure
function analyses. Individual blazars show a wide range of variability
amplitudes, timescales, and duty cycles. Of the best sampled objects, 35% are
seen to vary by more than 0.4 magnitudes; for these, the fraction of
measurements contributing to the high amplitude variability ranges constantly
from about 5% to 80%. Blazar variability has some similarities to that of type
I quasars but includes larger amplitude fluctuations on all timescales. FSRQ
variability amplitudes are particularly similar to those of QSOs on timescales
of several months, suggesting significant contributions from the accretion disk
to the variable flux at these timescales. Optical variability amplitudes are
correlated with the maximum apparent velocities of the radio jet for the subset
of FSRQs with MOJAVE VLBA measurements, implying that the optically variable
flux's strength is typically related to that of the radio emission. We also
study CRATES radio-selected FSRQ candidates, which show similar variability
characteristics to known FSRQs; this suggests a high purity for the CRATES
sample.Comment: 29 pages, 12 figures. Accepted for publication in Ap
Measuring Lensing Magnification of Quasars by Large Scale Structure using the Variability-Luminosity Relation
We introduce a technique to measure gravitational lensing magnification using
the variability of type I quasars. Quasars' variability amplitudes and
luminosities are tightly correlated, on average. Magnification due to
gravitational lensing increases the quasars' apparent luminosity, while leaving
the variability amplitude unchanged. Therefore, the mean magnification of an
ensemble of quasars can be measured through the mean shift in the
variability-luminosity relation. As a proof of principle, we use this technique
to measure the magnification of quasars spectroscopically identified in the
Sloan Digital Sky Survey, due to gravitational lensing by galaxy clusters in
the SDSS MaxBCG catalog. The Palomar-QUEST Variability Survey, reduced using
the DeepSky pipeline, provides variability data for the sources. We measure the
average quasar magnification as a function of scaled distance (r/R200) from the
nearest cluster; our measurements are consistent with expectations assuming NFW
cluster profiles, particularly after accounting for the known uncertainty in
the clusters' centers. Variability-based lensing measurements are a valuable
complement to shape-based techniques because their systematic errors are very
different, and also because the variability measurements are amenable to
photometric errors of a few percent and to depths seen in current wide-field
surveys. Given the data volume expected from current and upcoming surveys, this
new technique has the potential to be competitive with weak lensing shear
measurements of large scale structure.Comment: Accepted for publication in Ap