7,046 research outputs found
Six Peaks Visible in the Redshift Distribution of 46,400 SDSS Quasars Agree with the Preferred Redshifts Predicted by the Decreasing Intrinsic Redshift Model
The redshift distribution of all 46,400 quasars in the Sloan Digital Sky
Survey (SDSS) Quasar Catalog III, Third Data Release, is examined. Six Peaks
that fall within the redshift window below z = 4, are visible. Their positions
agree with the preferred redshift values predicted by the decreasing intrinsic
redshift (DIR) model, even though this model was derived using completely
independent evidence. A power spectrum analysis of the full dataset confirms
the presence of a single, significant power peak at the expected redshift
period. Power peaks with the predicted period are also obtained when the upper
and lower halves of the redshift distribution are examined separately. The
periodicity detected is in linear z, as opposed to log(1+z). Because the peaks
in the SDSS quasar redshift distribution agree well with the preferred
redshifts predicted by the intrinsic redshift relation, we conclude that this
relation, and the peaks in the redshift distribution, likely both have the same
origin, and this may be intrinsic redshifts, or a common selection effect.
However, because of the way the intrinsic redshift relation was determined it
seems unlikely that one selection effect could have been responsible for both.Comment: 12 pages, 12 figure, accepted for publication in the Astrophysical
Journa
Distances of Quasars and Quasar-Like Galaxies: Further Evidence that QSOs may be Ejected from Active Galaxies
If high-redshift QSOs are ejected from the nuclei of low-redshift galaxies,
as some have claimed, a large portion of their redshift must be intrinsic
(non-Doppler). If these intrinsic components have preferred values, redshifts
will tend to cluster around these preferred values and produce peaks in the
redshift distribution. Doppler ejection and Hubble flow components will broaden
each peak. Because ejection velocities are randomly directed and Hubble flow
components are always positive, in this model all peaks are expected to show an
asymmetry, extending further out in the red wing. If peaks are present showing
this predicted asymmetry, it can lead directly to an estimate of quasar
distances. Using two quasar samples, one with high redshifts and one with low,
it is shown here that not only do all peaks in these two redshift distributions
occur at previously predicted preferred values, they also all show the
predicted extra extension in the red wing. For the low and high redshift
samples the mean cosmological components are found to be z and
, respectively. The difference can be explained by the improved
detection limit of the high redshift sample. These results offer further
evidence in favor of the model proposing that QSOs are ejected from active
galaxies.Comment: 11 pages, 6 figures, accepted for publication in The Astrophysical
Journa
Critical Examinations of QSO Redshift Periodicities and Associations with Galaxies in Sloan Digital Sky Survey Data
We have used the publicly available data from the Sloan Digital Sky Survey
and 2dF QSO Redshift Survey to test the hypothesis that QSOs are ejected from
active galaxies with periodic non-cosmological redshifts. For two different
intrinsic redshift models, namely the Karlsson model and Bell's
decreasing intrinsic redshift (DIR) model, we do two tests respectively. First,
using different criteria, we generate four sets of QSO-galaxy pairs and find
there is no evidence for a periodicity at the predicted frequency in
, or at any other frequency. We then check the relationship between
high redshift QSOs and nearby active galaxies, and we find the distribution of
projected distance between high redshift QSOs and nearby active galaxies and
the distribution of redshifts of those active galaxies are consistent with a
distribution of simulated random pairs, completely different from Bell's
previous conclusion. We also analyze the periodicity in redshifts of QSOs, and
no periodicity is found in high completeness samples, contrary to the DIR
model. These results support that QSOs are not ejected from active galaxies.Comment: 25 pages, 13 figures, accepted for publication in Ap
The Distribution of Redshifts in New Samples of Quasi-stellar Objects
Two new samples of QSOs have been constructed from recent surveys to test the
hypothesis that the redshift distribution of bright QSOs is periodic in
. The first of these comprises 57 different redshifts among all
known close pairs or multiple QSOs, with image separations 10\arcsec,
and the second consists of 39 QSOs selected through their X-ray emission and
their proximity to bright comparatively nearby active galaxies. The redshift
distributions of the samples are found to exhibit distinct peaks with a
periodic separation of in identical to that claimed
in earlier samples but now extended out to higher redshift peaks and 4.47, predicted by the formula but never seen before. The periodicity
is also seen in a third sample, the 78 QSOs of the 3C and 3CR catalogues. It is
present in these three datasets at an overall significance level -
, and appears not to be explicable by spectroscopic or similar
selection effects. Possible interpretations are briefly discussed.Comment: submitted for publication in the Astronomical Journal, 15 figure
Polarized Neutron Laue Diffraction on a Crystal Containing Dynamically Polarized Proton Spins
We report on a polarized-neutron Laue diffraction experiment on a single
crystal of neodynium doped lanthanum magnesium nitrate hydrate containing
polarized proton spins. By using dynamic nuclear polarization to polarize the
proton spins, we demonstrate that the intensities of the Bragg peaks can be
enhanced or diminished significantly, whilst the incoherent background, due to
proton spin disorder, is reduced. It follows that the method offers unique
possibilities to tune continuously the contrast of the Bragg reflections and
thereby represents a new tool for increasing substantially the signal-to-noise
ratio in neutron diffraction patterns of hydrogenous matter.Comment: 5 pages, 3 figure
Age-Depth Stratigraphy of Pine Island Glacier Inferred from Airborne Radar and Ice-Core Chronology
Understanding the contribution of the West Antarctic Ice Sheet (WAIS) to past and future sea level has been a major scientific priority over the last three decades. In recent years, observed thinning and iceâflow acceleration of the marineâbased Pine Island Glacier has highlighted that understanding dynamic changes is critical to predicting the longâterm stability of the WAIS. However, relatively little is known about the evolution of the catchment during the Holocene. Internal Reflecting Horizons (IRHs) provide a cumulative record of accumulation, basal melt and ice dynamics that, if dated, can be used to constrain iceâflow models. Here, we use airborne radars to trace four spatiallyâextensive IRHs deposited in the late Quaternary across the Pine Island Glacier catchment. We use the WAIS Divide iceâcore chronology to assign ages to three IRHs: 4.72 ± 0.28, 6.94 ± 0.31, and 16.50 ± 0.79 ka. We use a 1âD model, constrained by observational and modelled accumulation rates, to produce an independent validation of our iceâcoreâderived ages and provide an age estimate for our shallowest IRH (2.31â2.92 ka). We find that our upper three IRHs correspond to three large peaks in sulphate concentrations in the WAIS Divide iceâcore record and hypothesise that the origin of these spatiallyâextensive IRHs is from past volcanic activity. The clear correspondence between our IRHs and the ones previously identified over the Weddell Sea Sector, altogether representing âŒ20% of the WAIS, indicates that a unique set of stratigraphic markers spanning the Holocene exists over a large part of West Antarctica
A measurement of the differential cross section for the two-body photodisintegration of 3He at theta_LAB = 90deg using tagged photons in the energy range 14 -- 31 MeV
The two-body photodisintegration of 3He has been investigated using tagged
photons with energies from 14 -- 31 MeV at MAX-lab in Lund, Sweden. The
two-body breakup channel was unambiguously identified by the (nonsimultaneous)
detection of both protons and deuterons. This approach was made feasible by the
over-determined kinematic situation afforded by the tagged-photon technique.
Proton- and deuteron-energy spectra were measured using four silicon
surface-barrier detector telescopes located at a laboratory angle of 90deg with
respect to the incident photon-beam direction. Average statistical and
systematic uncertainties of 5.7% and 6.6% in the differential cross section
were obtained for 11 photon-energy bins with an average width of 1.2 MeV. The
results are compared to previous experimental data measured at comparable
photon energies as well as to the results of two recent Faddeev calculations
which employ realistic potential models and take into account three-nucleon
forces and final-state interactions. Both the accuracy and precision of the
present data are improved over the previous measurements. The data are in good
agreement with most of the previous results, and favor the inclusion of
three-nucleon forces in the calculations.Comment: 12 pages, 13 figures; further Referee comments addresse
High-efficiency quantum interrogation measurements via the quantum Zeno effect
The phenomenon of quantum interrogation allows one to optically detect the
presence of an absorbing object, without the measuring light interacting with
it. In an application of the quantum Zeno effect, the object inhibits the
otherwise coherent evolution of the light, such that the probability that an
interrogating photon is absorbed can in principle be arbitrarily small. We have
implemented this technique, demonstrating efficiencies exceeding the 50%
theoretical-maximum of the original ``interaction-free'' measurement proposal.
We have also predicted and experimentally verified a previously unsuspected
dependence on loss; efficiencies of up to 73% were observed and the feasibility
of efficiencies up to 85% was demonstrated.Comment: 4 pages, 3 postscript figures. To appear in Phys. Rev. Lett;
submitted June 11, 199
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