201 research outputs found
An in situ instrument for planar O2 optode measurements at benthic interfaces
A new in situ instrument for two‐dimensional mapping of oxygen in coastal sediments is presented. The measuring principle is described, and potential mechanical disturbances, solute and particle smearing associated with the measurements, and calibration routines are evaluated. The first in situ measurements obtained in two different benthic communities are presented. In a shallow photosynthetic sediment (1 m of water depth), an extensive horizontal and temporal variation in the O2 distribution caused by benthic photosynthesis and irrigating fauna was resolved. Repetitive planar optode measurements performed along a transect in central Øresund, Denmark (17 m of water depth) revealed a positive correlation between the apparent O2 penetration depths (OP) measured with a lateral distance <5.0 mm, whereas OP measured with a larger horizontal distance (up to 50 m) were not correlated. Consequently, the OP varied in patches with a characteristic size of 5.0 mm. The instrument described is a powerful new tool for in situ characterization of spatiotemporal variations in O2 distributions within benthic communities. The instrument can be adapted for use at full ocean depths, e.g., on deep‐sea landers or remote operating vehicles
Cosmological implications of the KATRIN experiment
The upcoming Karlsruhe Tritium Neutrino (KATRIN) experiment will put
unprecedented constraints on the absolute mass of the electron neutrino,
\mnue. In this paper we investigate how this information on \mnue will
affect our constraints on cosmological parameters. We consider two scenarios;
one where \mnue=0 (i.e., no detection by KATRIN), and one where
\mnue=0.3eV. We find that the constraints on \mnue from KATRIN will affect
estimates of some important cosmological parameters significantly. For example,
the significance of and the inferred value of depend
on the results from the KATRIN experiment.Comment: 13 page
A Census of Star-Forming Galaxies in the z~9-10 Universe based on HST+Spitzer Observations Over 19 CLASH clusters: Three Candidate z~9-10 Galaxies and Improved Constraints on the Star Formation Rate Density at z~9
We utilise a two-color Lyman-Break selection criterion to search for z~9-10
galaxies over the first 19 clusters in the CLASH program. A systematic search
yields three z~9-10 candidates. While we have already reported the most robust
of these candidates, MACS1149-JD, two additional z~9 candidates are also found
and have H_{160}-band magnitudes of ~26.2-26.9. A careful assessment of various
sources of contamination suggests <~1 contaminants for our z~9-10 selection. To
determine the implications of these search results for the LF and SFR density
at z~9, we introduce a new differential approach to deriving these quantities
in lensing fields. Our procedure is to derive the evolution by comparing the
number of z~9-10 galaxy candidates found in CLASH with the number of galaxies
in a slightly lower redshift sample (after correcting for the differences in
selection volumes), here taken to be z~8. This procedure takes advantage of the
fact that the relative volumes available for the z~8 and z~9-10 selections
behind lensing clusters are not greatly dependent on the details of the lensing
models. We find that the normalization of the UV LF at z~9 is just
0.28_{-0.20}^{+0.39}\times that at z~8, ~1.4_{-0.8}^{+3.0}x lower than
extrapolating z~4-8 LF results. While consistent with the evolution in the UV
LF seen at z~4-8, these results marginally favor a more rapid evolution at z>8.
Compared to similar evolutionary findings from the HUDF, our result is less
insensitive to large-scale structure uncertainties, given our many independent
sightlines on the high-redshift universe.Comment: 22 pages, 11 figures, 5 tables, accepted for publication in the
Astrophysical Journal, updated to include the much deeper Spitzer/IRAC
observations over our three z~9-10 candidate
CLASH: A Census of Magnified Star-Forming Galaxies at z ~ 6-8
We utilize 16 band Hubble Space Telescope (HST) observations of 18 lensing
clusters obtained as part of the Cluster Lensing And Supernova survey with
Hubble (CLASH) Multi-Cycle Treasury program to search for galaxies.
We report the discovery of 204, 45, and 13 Lyman-break galaxy candidates at
, , and , respectively, identified from purely
photometric redshift selections. This large sample, representing nearly an
order of magnitude increase in the number of magnified star-forming galaxies at
presented to date, is unique in that we have observations in four
WFC3/UVIS UV, seven ACS/WFC optical, and all five WFC3/IR broadband filters,
which enable very accurate photometric redshift selections. We construct
detailed lensing models for 17 of the 18 clusters to estimate object
magnifications and to identify two new multiply lensed
candidates. The median magnifications over the 17 clusters are 4, 4, and 5 for
the , , and samples, respectively, over an average
area of 4.5 arcmin per cluster. We compare our observed number counts with
expectations based on convolving "blank" field UV luminosity functions through
our cluster lens models and find rough agreement down to mag, where we
begin to suffer significant incompleteness. In all three redshift bins, we find
a higher number density at brighter observed magnitudes than the field
predictions, empirically demonstrating for the first time the enhanced
efficiency of lensing clusters over field surveys. Our number counts also are
in general agreement with the lensed expectations from the cluster models,
especially at , where we have the best statistics.Comment: Accepted for publication in the Astrophysical Journal, 25 pages, 13
figures, 7 table
CLASH: z ~ 6 young galaxy candidate quintuply lensed by the frontier field cluster RXC J2248.7-4431
We present a quintuply lensed z ~ 6 candidate discovered in the field of the
galaxy cluster RXC J2248.7-4431 (z ~ 0.348) targeted within the Cluster Lensing
and Supernova survey with Hubble (CLASH) and selected in the deep HST Frontier
Fields survey. Thanks to the CLASH 16-band HST imaging, we identify the
quintuply lensed z ~ 6 candidate as an optical dropout in the inner region of
the cluster, the brightest image having magAB=24.81+-0.02 in the f105w filter.
We perform a detailed photometric analysis to verify its high-z and lensed
nature. We get as photometric redshift z_phot ~ 5.9, and given the extended
nature and NIR colours of the lensed images, we rule out low-z early type and
galactic star contaminants. We perform a strong lensing analysis of the
cluster, using 13 families of multiple lensed images identified in the HST
images. Our final best model predicts the high-z quintuply lensed system with a
position accuracy of 0.8''. The magnifications of the five images are between
2.2 and 8.3, which leads to a delensed UV luminosity of L_1600 ~ 0.5L*_1600 at
z=6. We also estimate the UV slope from the observed NIR colours, finding a
steep beta=-2.89+-0.38. We use singular and composite stellar population SEDs
to fit the photometry of the hiz candidate, and we conclude that it is a young
(age <300 Myr) galaxy with mass of M ~ 10^8Msol, subsolar metallicity
(Z<0.2Zsol) and low dust content (AV ~ 0.2-0.4).Comment: 21 pages, 13 figures, 6 tables, submitted to MNRAS on 11 Aug 2013,
accepted on 23 Nov 201
CLASH: New Multiple-Images Constraining the Inner Mass Profile of MACS J1206.2-0847
We present a strong-lensing analysis of the galaxy cluster MACS J1206.2-0847
(=0.44) using UV, Optical, and IR, HST/ACS/WFC3 data taken as part of the
CLASH multi-cycle treasury program, with VLT/VIMOS spectroscopy for some of the
multiply-lensed arcs. The CLASH observations, combined with our mass-model,
allow us to identify 47 new multiply-lensed images of 12 distant sources. These
images, along with the previously known arc, span the redshift range 1\la
z\la5.5, and thus enable us to derive a detailed mass distribution and to
accurately constrain, for the first time, the inner mass-profile of this
cluster. We find an inner profile slope of (in the range [1\arcsec, 53\arcsec], or 5\la r \la300 kpc), as
commonly found for relaxed and well-concentrated clusters. Using the many
systems uncovered here we derive credible critical curves and Einstein radii
for different source redshifts. For a source at , the critical
curve encloses a large area with an effective Einstein radius of
\theta_{E}=28\pm3\arcsec, and a projected mass of . From the current understanding of structure formation in
concordance cosmology, these values are relatively high for clusters at
, so that detailed studies of the inner mass distribution of clusters
such as MACS J1206.2-0847 can provide stringent tests of the CDM
paradigm.Comment: 7 pages, 1 table, 4 figures; submitted to ApJ Letters; V3: minor
correction
The Cluster Lensing and Supernova Survey with Hubble (CLASH): Strong Lensing Analysis of Abell 383 from 16-Band HST WFC3/ACS Imaging
We examine the inner mass distribution of the relaxed galaxy cluster Abell
383 in deep 16-band HST/ACS+WFC3 imaging taken as part of the CLASH multi-cycle
treasury program. Our program is designed to study the dark matter distribution
in 25 massive clusters, and balances depth with a wide wavelength coverage to
better identify lensed systems and generate precise photometric redshifts. This
information together with the predictive strength of our strong-lensing
analysis method identifies 13 new multiply-lensed images and candidates, so
that a total of 27 multiple-images of 9 systems are used to tightly constrain
the inner mass profile, (r<160 kpc).
We find consistency with the standard distance-redshift relation for the full
range spanned by the lensed images, 1.01<z<6.03, with the higher redshift
sources deflected through larger angles as expected. The inner mass profile
derived here is consistent with the results of our independent weak-lensing
analysis of wide-field Subaru images, with good agreement in the region of
overlap. The overall mass profile is well fitted by an NFW profile with
M_{vir}=(5.37^{+0.70}_{-0.63}\pm 0.26) x 10^{14}M_{\odot}/h and a relatively
high concentration, c_{vir}=8.77^{+0.44}_{-0.42}\pm 0.23, which lies above the
standard c-M relation similar to other well-studied clusters. The critical
radius of Abell 383 is modest by the standards of other lensing clusters,
r_{E}\simeq16\pm2\arcsec (for z_s=2.55), so the relatively large number of
lensed images uncovered here with precise photometric redshifts validates our
imaging strategy for the CLASH survey. In total we aim to provide similarly
high-quality lensing data for 25 clusters, 20 of which are X-ray selected
relaxed clusters, enabling a precise determination of the representative mass
profile free from lensing bias. (ABRIDGED)Comment: 15 pages, 14 figures, 2 tabels; V3 matches the submitted version
later published in Ap
Constraining New Physics with a Positive or Negative Signal of Neutrino-less Double Beta Decay
We investigate numerically how accurately one could constrain the strengths
of different short-range contributions to neutrino-less double beta decay in
effective field theory. Depending on the outcome of near-future experiments
yielding information on the neutrino masses, the corresponding bounds or
estimates can be stronger or weaker. A particularly interesting case, resulting
in strong bounds, would be a positive signal of neutrino-less double beta decay
that is consistent with complementary information from neutrino oscillation
experiments, kinematical determinations of the neutrino mass, and measurements
of the sum of light neutrino masses from cosmological observations. The keys to
more robust bounds are improvements of the knowledge of the nuclear physics
involved and a better experimental accuracy.Comment: 23 pages, 3 figures. Minor changes. Matches version published in JHE
The impact of going beyond the Maxwell distribution in direct dark matter detection rates
We consider direct dark matter detection rates and investigate the difference
between a standard Maxwell-Boltzmann velocity distribution and a "realistic"
distribution like the ones extracted from numerical N-body simulations. Sizable
differences are observed when such results are compared to the standard
Maxwell-Boltzmann distribution. For a light target both the total rate and the
annual modulation are reduced by ~25%. For a heavy target the total rate is
virtually unchanged, whereas the annual modulation is modified by up to 50%,
depending on the WIMP mass and detector energy threshold. We also consider the
effect of a possible velocity anisotropy, and the effect is found to be largest
for a light target For the realistic velocity distribution the anisotropy may
reduce the annual modulation, in contrast to the Maxwell-Boltzmann case.Comment: 13 pages, 10 figures, accepted by Phys. Rev.
Clash: The concentration-mass relation of galaxy clusters
The Astrophysical Journal 806.1 (2015): 4 reproduced by permission of the AASWe present a new determination of the concentration-mass (c-M) relation for galaxy clusters based on our comprehensive lensing analysis of 19 X-ray selected galaxy clusters from the Cluster Lensing and Supernova Survey with Hubble (CLASH). Our sample spans a redshift range between 0.19 and 0.89. We combine weak-lensing constraints from the Hubble Space Telescope (HST) and from ground-based wide-field data with strong lensing constraints from HST. The results are reconstructions of the surface-mass density for all CLASH clusters on multi-scale grids. Our derivation of Navarro-Frenk-White parameters yields virial masses between 0.53 x 10 15 M⊙/ h and 1.76 x 10 15 M⊙/ h and the halo concentrations are distributed around c200c∼3.7 with a 1σ significant negative slope with cluster mass. We find an excellent 4% agreement in the median ratio of our measured concentrations for each cluster and the respective expectation from numerical simulations after accounting for the CLASH selection function based on X-ray morphology. The simulations are analyzed in two dimensions to account for possible biases in the lensing reconstructions due to projection effects. The theoretical c-M relation from our X-ray selected set of simulated clusters and the c-M relation derived directly from the CLASH data agree at the 90% confidence levelThe research was in part carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
J. M. has received funding from the People Programme (Marie Curie Actions) of the European Unionʼs Seventh Framework Programme (FP7/2007–2013) under REA grant
agreement number 627288. M. M. thanks ORAU and NASA for supporting his research at JPL and acknowledges support from the contract ASI/INAF I/023/12/0, INFN/PD51, and the PRIN MIUR 20102011 “The dark universe and the cosmic evolution of baryons: from current surveys to Euclid.” K. U. acknowledges support from the National Science Council of Taiwan (grant NSC100-2112-M-001-008-MY3) and from the Academia Sinica Career Development Award. Support for A. Z. is provided by NASA through Hubble Fellowship grant #HST-HF-51334.01 A awarded by STScI. D. G., S. S. and P. R. were supported by SFB Transregio 33 “The Dark universe” by the Deutsche Forschungsgemeinschaft (DFG) and the DFG cluster of excellence “Origin and Structure of the universe.” This work was supported in part by contract research “Internationale Spitzenforschung II/2-6” of the Baden Württemberg Stiftung. The Dark Cosmology Centre is funded by the DNRF. J. S. was supported by NSF/AST1313447, NASA/NNX11AB07G, and the Norris Foundation CCAT Postdoctoral Fellowship. E.R. acknowledges support from the National Science Foundation AST-1210973, SAO TM3-14008X (issued under NASA Contract No. NAS8-03060
- …
