166 research outputs found
The XXL Survey V: Detection of the Sunyaev-Zel'dovich effect of the Redshift 1.9 Galaxy Cluster XLSSU J021744.1-034536 with CARMA
We report the detection of the Sunyaev-Zel'dovich (SZ) effect of galaxy
cluster XLSSU J021744.1-034536, using 30 GHz CARMA data. This cluster was
discovered via its extended X-ray emission in the XMM-Newton Large Scale
Structure survey, the precursor to the XXL survey. It has a photometrically
determined redshift , making it among the most distant
clusters known, and nominally the most distant for which the SZ effect has been
measured. The spherically integrated Comptonization is
, a measurement which is relatively
insensitive to assumptions regarding the size and redshift of the cluster, as
well as the background cosmology. Using a variety of locally calibrated cluster
scaling relations extrapolated to z~2, we estimate a mass - from the X-ray flux and SZ signal. The measured
properties of this cluster are in good agreement with the extrapolation of an
X-ray luminosity-SZ effect scaling relation calibrated from clusters discovered
by the South Pole Telescope at higher masses and lower redshifts. The full
XXL-CARMA sample will provide a more complete, multi-wavelength census of
distant clusters in order to robustly extend the calibration of cluster scaling
relations to these high redshifts.Comment: ApJ, in press. 9 pages, 4 figures, 4 table
CARMA Measurements of the Sunyaev-Zel'dovich Effect in RXJ1347.5-1145
We demonstrate the Sunyaev-Zel'dovich (SZ) effect imaging capabilities of the
Combined Array for Research in Millimeter-wave Astronomy (CARMA) by presenting
an SZ map of the galaxy cluster RXJ1347.5-1145. By combining data from multiple
CARMA bands and configurations, we are able to capture the structure of this
cluster over a wide range of angular scales, from its bulk properties to its
core morphology. We find that roughly 9% of this cluster's thermal energy is
associated with sub-arcminute-scale structure imparted by a merger,
illustrating the value of high-resolution SZ measurements for pursuing cluster
astrophysics and for understanding the scatter in SZ scaling relations. We also
find that the cluster's SZ signal is lower in amplitude than suggested by a
spherically-symmetric model derived from X-ray data, consistent with
compression along the line of sight relative to the plane of the sky. Finally,
we discuss the impact of upgrades currently in progress that will further
enhance CARMA's power as an SZ imaging instrument.Comment: 8 pages, 6 figure
Constraints on the Thermal Contents of the X-ray Cavities of Cluster MS 0735.6+7421 with Sunyaev-Zel'dovich Effect Observations
Outbursts from active galactic nuclei (AGN) can inflate cavities in the
intracluster medium (ICM) of galaxy clusters and are believed to play the
primary role in offsetting radiative cooling in the ICM. However, the details
of how the energy from AGN feedback thermalizes to heat the ICM is not well
understood, partly due to the unknown composition and energetics of the
cavities. The Sunyaev-Zel'dovich (SZ) effect, a measure of the integrated
pressure along the line of sight, provides a means of measuring the thermal
contents of the cavities, to discriminate between thermal, nonthermal, and
other sources of pressure support. Here we report measurements of the SZ effect
at 30 GHz toward the galaxy cluster MS 0735.6+7421 (MS0735), using the Combined
Array for Research in Millimeter-wave Astronomy (CARMA). MS0735 hosts the most
energetic AGN outburst known and lobes of radio synchrotron emission coincident
with a pair of giant X-ray cavities across. Our CARMA maps show a
clear deficit in the SZ signal coincident with the X-ray identified cavities,
when compared to a smooth X-ray derived pressure model. We find that the
cavities have very little SZ-contributing material, suggesting that they are
either supported by very diffuse thermal plasma with temperature in excess of
hundreds of keV, or are not supported thermally. Our results represent the
first detection (with significance) of this phenomenon with the SZ
effect.Comment: 15 pages, 9 figures, submitted to ApJ Jun 2018, Accepted Dec 2018,
Published Jan 2019. This is the version of the article before editing, as
submitted by an author to ApJ. IOP Publishing Ltd is not responsible for any
errors or omissions in this version of the manuscript or any version derived
from it. The Version of Record is available online at
https://doi.org/10.3847/1538-4357/aaf88
THE MASSIVE AND DISTANT CLUSTERS OF WISE SURVEY. III. SUNYAEV-ZEL'DOVICH MASSES OF GALAXY CLUSTERS AT z ~ 1
We present CARMA 30 GHz Sunyaev–Zel'dovich (SZ) observations of five high-redshift (z [> over ~] 1), infrared-selected galaxy clusters discovered as part of the all-sky Massive and Distant Clusters of WISE Survey (MaDCoWS). The SZ decrements measured toward these clusters demonstrate that the MaDCoWS selection is discovering evolved, massive galaxy clusters with hot intracluster gas. Using the SZ scaling relation calibrated with South Pole Telescope clusters at similar masses and redshifts, we find these MaDCoWS clusters have masses in the range M[subscript 200] ≈ 2-6 X 10[superscript 14] M[subscript ʘ. Three of these are among the most massive clusters found to date at z [> over ~] 1, demonstrating that MaDCoWS is sensitive to the most massive clusters to at least z = 1.3. The added depth of the AllWISE data release will allow all-sky infrared cluster detection to z ≈ 1.5 and beyond
High-Resolution Sampling of a Broad Marine Life Size Spectrum Reveals Differing Size- and Composition-Based Associations With Physical Oceanographic Structure
Observing multiple size classes of organisms, along with oceanographic properties and water mass origins, can improve our understanding of the drivers of aggregations, yet acquiring these measurements remains a fundamental challenge in biological oceanography. By deploying multiple biological sampling systems, from conventional bottle and net sampling to in situ imaging and acoustics, we describe the spatial patterns of different size classes of marine organisms (several microns to ∼10 cm) in relation to local and regional (m to km) physical oceanographic conditions on the Delaware continental shelf. The imaging and acoustic systems deployed included (in ascending order of target organism size) an imaging flow cytometer (CytoSense), a digital holographic imaging system (HOLOCAM), an In Situ Ichthyoplankton Imaging System (ISIIS, 2 cameras with different pixel resolutions), and multi-frequency acoustics (SIMRAD, 18 and 38 kHz). Spatial patterns generated by the different systems showed size-dependent aggregations and differing connections to horizontal and vertical salinity and temperature gradients that would not have been detected with traditional station-based sampling (∼9-km resolution). A direct comparison of the two ISIIS cameras showed composition and spatial patchiness changes that depended on the organism size, morphology, and camera pixel resolution. Large zooplankton near the surface, primarily composed of appendicularians and gelatinous organisms, tended to be more abundant offshore near the shelf break. This region was also associated with high phytoplankton biomass and higher overall organism abundances in the ISIIS, acoustics, and targeted net sampling. In contrast, the inshore region was dominated by hard-bodied zooplankton and had relatively low acoustic backscatter. The nets showed a community dominated by copepods, but they also showed high relative abundances of soft-bodied organisms in the offshore region where these organisms were quantified by the ISIIS. The HOLOCAM detected dense patches of ciliates that were too small to be captured in the nets or ISIIS imagery. This near-simultaneous deployment of different systems enables the description of the spatial patterns of different organism size classes, their spatial relation to potential prey and predators, and their association with specific oceanographic conditions. These datasets can also be used to evaluate the efficacy of sampling techniques, ultimately aiding in the design of efficient, hypothesis-driven sampling programs that incorporate these complementary technologies
Has Devolution Changed the 'British Policy Style'?
The term ‘policy style' simply means the way that governments make and implement policy. Yet, the term ‘British policy style' may be confusing since it has the potential to relate to British exceptionalism or European convergence. Lijphart's important contribution identifies the former. It sets up a simple distinction between policy styles in majoritarian and consensual democracies and portrays British policy-making as top down and different from a consensual European approach. In contrast, Richardson identifies a common ‘European policy style'. This suggests that although the political structures of each country vary, they share a ‘standard operating procedure' based on two factors - an incremental approach to policy and an attempt to reach a consensus with interest groups rather than impose decisions. This article extends these arguments to British politics since devolution. It questions the assumption that policy styles are diverging within Britain. Although consultation in the devolved territories may appear to be more consensual, they are often contrasted with a caricature of the UK process based on atypical examples of top-down policy-making. While there may be a different ‘feel' to participation in Scotland and Wales, a similar logic of consultation and bureaucratic accommodation exists in the UK. This suggests that, although devolution has made a difference, a British (or European) policy style can still be identified
String-like Clusters and Cooperative Motion in a Model Glass-Forming Liquid
A large-scale molecular dynamics simulation is performed on a glass-forming
Lennard-Jones mixture to determine the nature of dynamical heterogeneities
which arise in this model fragile liquid. We observe that the most mobile
particles exhibit a cooperative motion in the form of string-like paths
(``strings'') whose mean length and radius of gyration increase as the liquid
is cooled. The length distribution of the strings is found to be similar to
that expected for the equilibrium polymerization of linear polymer chains.Comment: 6 pages of RevTex, 6 postscript figures, uses epsf.st
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