947 research outputs found
Calibration of the Mass-Temperature Relation for Clusters of Galaxies Using Weak Gravitational Lensing
The main uncertainty in current determinations of the power spectrum
normalization, sigma_8, from abundances of X-ray luminous galaxy clusters
arises from the calibration of the mass-temperature relation. We use our weak
lensing mass determinations of 30 clusters from the hitherto largest sample of
clusters with lensing masses, combined with X-ray temperature data from the
literature, to calibrate the normalization of this relation at a temperature of
8 keV, M_{500c,8 keV}=(8.7 +/- 1.6) h^{-1} 10^{14} M_sun. This normalization is
consistent with previous lensing-based results based on smaller cluster
samples, and with some predictions from numerical simulations, but higher than
most normalizations based on X-ray derived cluster masses. Assuming the
theoretically expected slope alpha=3/2 of the mass-temperature relation, we
derive sigma_8 = 0.88 +/-0.09 for a spatially-flat LambdaCDM universe with
Omega_m = 0.3. The main systematic errors on the lensing masses result from
extrapolating the cluster masses beyond the field-of-view used for the
gravitational lensing measurements, and from the separation of
cluster/background galaxies, contributing each with a scatter of 20%. Taking
this into account, there is still significant intrinsic scatter in the
mass-temperature relation indicating that this relation may not be very tight,
at least at the high mass end. Furthermore, we find that dynamically relaxed
clusters are 75 +/-40% hotter than non-relaxed clusters.Comment: 8 pages, 4 figures, revised version submitted to Ap
A weak lensing analysis of the PLCK G100.2-30.4 cluster
We present a mass estimate of the Planck-discovered cluster PLCK G100.2-30.4,
derived from a weak lensing analysis of deep SUBARU griz images. We perform a
careful selection of the background galaxies using the multi-band imaging data,
and undertake the weak lensing analysis on the deep (1hr) r-band image. The
shape measurement is based on the KSB algorithm; we adopt the PSFex software to
model the Point Spread Function (PSF) across the field and correct for this in
the shape measurement. The weak lensing analysis is validated through extensive
image simulations. We compare the resulting weak lensing mass profile and total
mass estimate to those obtained from our re-analysis of XMM-Newton
observations, derived under the hypothesis of hydrostatic equilibrium. The
total integrated mass profiles are in remarkably good agreement, agreeing
within 1 across their common radial range. A mass is derived for the cluster from our weak lensing
analysis. Comparing this value to that obtained from our reanalysis of
XMM-Newton data, we obtain a bias factor of (1-b) = 0.8 0.1. This is
compatible within 1 with the value of (1-b) obtained by Planck
Collaboration XXIV from their calibration of the bias factor using
newly-available weak lensing reconstructed masses.Comment: 11 pages, 12 figures, accepted for publication on Astronomy &
Astrophysics; updates in affiliation
Spatially Resolved Outflows in a Seyfert Galaxy at z = 2.39
We present the first spatially resolved analysis of rest-frame optical and UV
imaging and spectroscopy for a lensed galaxy at z = 2.39 hosting a Seyfert
active galactic nucleus (AGN). Proximity to a natural guide star has enabled
high signal-to-noise VLT SINFONI + adaptive optics observations of rest-frame
optical diagnostic emission lines, which exhibit an underlying broad component
with FWHM ~ 700 km/s in both the Balmer and forbidden lines. Measured line
ratios place the outflow robustly in the region of the ionization diagnostic
diagrams associated with AGN. This unique opportunity - combining gravitational
lensing, AO guiding, redshift, and AGN activity - allows for a magnified view
of two main tracers of the physical conditions and structure of the
interstellar medium in a star-forming galaxy hosting a weak AGN at cosmic noon.
By analyzing the spatial extent and morphology of the Ly-alpha and
dust-corrected H-alpha emission, disentangling the effects of star formation
and AGN ionization on each tracer, and comparing the AGN induced mass outflow
rate to the host star formation rate, we find that the AGN does not
significantly impact the star formation within its host galaxy.Comment: 16 pages, 5 figures, accepted for publication in Ap
Genetic diversity within and among Atlantic cod (Gadus morhua) farmed in marine cages: a proof-of-concept study for the identification of escapees
This study presents a molecular genetic characterization of Atlantic cod reared in commercial marine farms. Samples consisted of approximately 47 fish collected from nine cages located on four farms throughout Norway. In addition, 28 farmed escapees were recaptured in the sea (443 fish in total). Nine microsatellite loci and the Pan I gene were analysed, revealing a total of 181 alleles. Each sample contained 43–63% of total allelic variation. Comparing variation with published data for wild cod indicates that lower genetic variation exists within single cages than in wild populations. Significant linkage disequilibrium was observed amongst pairs of loci in all samples, suggesting a low number of contributing parental fish. Global FST was 0.049, and the highest pairwise FST value (pooled loci) was 0.085. For single loci, the Pan I gene was the most diagnostic, displaying a global FST of 0.203. Simulations amongst the samples collected on farms revealed an overall correct self-assignment percentage of 75%, demonstrating a high probability of identifying individuals to their farm of origin. Identification of the 28 escapees revealed a single cage as the most likely source of origin for half of the escapees, whilst the remaining fish were assigned to a mixture of samples, suggesting more than one source of escapees
Prospects for high-z cluster detections with Planck, based on a follow-up of 28 candidates using MegaCam@CFHT
The Planck catalogue of SZ sources limits itself to a significance threshold
of 4.5 to ensure a low contamination rate by false cluster candidates. This
means that only the most massive clusters at redshift z>0.5, and in particular
z>0.7, are expected to enter into the catalogue, with a large number of systems
in that redshift regime being expected around and just below that threshold. In
this paper, we follow-up a sample of SZ sources from the Planck SZ catalogues
from 2013 and 2015. In the latter maps, we consider detections around and at
lower significance than the threshold adopted by the Planck Collaboration. To
keep the contamination rate low, our 28 candidates are chosen to have
significant WISE detections, in combination with non-detections in SDSS/DSS,
which effectively selects galaxy cluster candidates at redshifts .
By taking r- and z-band imaging with MegaCam@CFHT, we bridge the 4000A
rest-frame break over a significant redshift range, thus allowing accurate
redshift estimates of red-sequence cluster galaxies up to z~0.8. After
discussing the possibility that an overdensity of galaxies coincides -by
chance- with a Planck SZ detection, we confirm that 16 of the candidates have
likely optical counterparts to their SZ signals, 13 (6) of which have an
estimated redshift z>0.5 (z>0.7). The richnesses of these systems are generally
lower than expected given the halo masses estimated from the Planck maps.
However, when we follow a simplistic model to correct for Eddington bias in the
SZ halo mass proxy, the richnesses are consistent with a reference
mass-richness relation established for clusters detected at higher
significance. This illustrates the benefit of an optical follow-up, not only to
obtain redshift estimates, but also to provide an independent mass proxy that
is not based on the same data the clusters are detected with, and thus not
subject to Eddington bias.Comment: 13 pages, 7 figures. Accepted for publication in A&
Annihilation of NMSSM neutralinos in the Sun and neutrino telescope limits
We investigate neutralino dark matter in the framework of NMSSM performing a
scan over its parameter space and calculating neutralino capture and
annihilation rates in the Sun. We discuss the prospects of searches for
neutralino dark matter in neutrino experiments depending on neutralino content
and its main annihilation channel. We recalculate the upper limits on
neutralino-proton elastic cross sections directly from neutrino telescopes
upper bounds on annihilation rates in the Sun. This procedure has advantages as
compared with corresponding recalcalations from the limits on muon flux,
namely, it is independent on details of the experiment and the recalculation
coefficients are universal for any kind of WIMP dark matter models. We derive
90% c.l. upper limits on neutralino-proton cross sections from the results of
the Baksan Underground Scintillator Telescope.Comment: 28 pages, 16 figures, accepted for publication in JCAP, references
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Effects of asphericity and substructure on the determination of cluster mass with weak gravitational lensing
Weak gravitational lensing can be used to directly measure the mass along a
line-of-sight without any dependence on the dynamical state of the mass, and
thus can be used to measure the masses of clusters even if they are not
relaxed. One common technique used to measure cluster masses is fitting
azimuthally-averaged gravitational shear profiles with a spherical mass model.
In this paper we quantify how asphericity and projected substructure in
clusters can affect the virial mass and concentration measured with this
technique by simulating weak lensing observations on 30 independent
lines-of-sights through each of four high-resolution N-body cluster
simulations. We find that the variations in the measured virial mass and
concentration are of a size similar to the error expected in ideal weak lensing
observations and are correlated, but that the virial mass and concentration of
the mean shear profile agree well with that measured in three dimensional
models of the clusters. The dominant effect causing the variations is the
proximity of the line-of-sight to the major axis of the 3-D cluster mass
distribution, with projected substructure only causing minor perturbations in
the measured concentration. Finally we find that the best-fit "universal" CDM
models used to fit the shear profiles over-predict the surface density of the
clusters due to the cluster mass density falling off faster than the r^{-3}
model assumption.Comment: 10 pages, 10 figures, accepted by MNRA
Supraclavicular Subclavian Access for Sapien Transcatheter Aortic Valve Replacement: A Novel Approach
BACKGROUND:
Within the trans-subclavian approach, procedural techniques can vary widely, and reported access generally refers to an infraclavicular axillary approach. We describe and report the use of a novel supraclavicular true subclavian approach for transcatheter aortic valve replacement (TAVR) exclusively for implantation of Sapien 3 valves. CASE PRESENTATION:
We report our first five consecutive patients undergoing TAVR with a Sapien 3 valve using a standardized subclavian approach at a single center. In-hospital and 30-day complications were reported. The use of this approach resulted in successful implantation in 100% of patients in a safe manner with 0% mortality, stroke, and vascular injury during hospitalization and at 30 day follow-up. The in-hospital pacemaker implantation rate was 20%. The average length of stay was 3 days. CONCLUSIONS:
TAVR with Sapien implant can be safely performed with a standardized supraclavicular subclavian approach in patients with unfavorable femoral access
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