263 research outputs found
Embedded Commissioning for Building Design
Building Commissioning has a broad scope that extends to all phases of building delivery. We view commissioning
as a building delivery embedded process that persistently verifies and validates design intent throughout the building lifecycle process.
In the building lifecycle approach, buildings are considered to have cradle-to-grave life spans. They are modeled through a variety
of different developmental phases. In this research project, we intend to build the necessary theory and tools to support the
embedded commissioning process as a co-function of building lifecycle
EROSITA Spectro-Imaging Analysis of the Abell 3408 Galaxy Cluster
The X-ray telescope eROSITA onboard the newly launched SRG mission
serendipitously observed the galaxy cluster A3408 () during the PV
observation of the AGN 1H0707-495. Despite its brightness and large extent, it
has not been observed by any modern X-ray observatory. A neighbouring cluster
in NW direction, A3407 (), appears to be close at least in projection
( Mpc). This cluster pair could be in a pre- or post-merger state.
We perform a detailed X-ray analysis of A3408. We construct particle
background subtracted and exposure corrected images and surface brightness
profiles in different sectors. The spectral analysis is performed out to
. Additionally, a temperature map is presented depicting the
distribution of the ICM temperature. Furthermore, we make use of data from the
RASS to estimate some bulk properties of A3408 and A3407, using the growth
curve analysis method and scaling relations.
The imaging analysis shows a complex morphology of A3408 with a strong
elongation in SE-NW direction. This is quantified by comparing the surface
brightness profiles of the NW, SW, SE and NE directions, where the NW and SE
directions show a significantly higher surface brightness compared to the other
directions. We determine a gas temperature
keV. The T-profile reveals a hot core within of the emission peak, keV. Employing a M-T relation, we obtain
iteratively. The of
A3407 and A3408 are found to overlap in projection which makes ongoing
interactions plausible. The 2d T-map reveals higher temperatures in W than in E
direction.
A3407 and A3408 are likely in a pre-merger state, affecting the ICM
properties, i.e., increased temperatures in the direction of A3407 indicate
adiabatic compression or shocks due to the interaction.Comment: 10 pages, 7 figures (main text), 2 figures (appendix). Submitted to
A&A for the Special Issue: The Early Data Release of eROSITA and Mikhail
Pavlinsky ART-XC on the SRG Missio
A search for inter-cluster filaments with LOFAR and eROSITA
Cosmological simulations predict the presence of warm hot thermal gas in the
cosmic filaments that connect galaxy clusters. This gas is thought to
constitute an important part of the missing baryons in the Universe. In
addition to the thermal gas, cosmic filaments could contain a population of
relativistic particles and magnetic fields. A detection of magnetic fields in
filaments can constrain early magnetogenesis in the cosmos. So far, the
resulting diffuse synchrotron emission has only been indirectly detected. We
present our search for thermal and non-thermal diffuse emission from
inter-cluster regions of 106 paired galaxy clusters by stacking the
~keV X-ray and 144~MHz radio data obtained with the eROSITA telescope
on board the Spectrum-Roentgen-Gamma (SRG) observatory and LOw Frequency ARray
(LOFAR), respectively. The stacked data do not show the presence of X-ray and
radio diffuse emission in the inter-cluster regions. This could be due to the
sensitivity of the data sets and/or the limited number of cluster pairs used in
this study. Assuming a constant radio emissivity in the filaments, we find that
the mean radio emissivity is not higher than . Under equipartition conditions, our upper limit
on the mean emissivity translates to an upper limit of for
the mean magnetic field strength in the filaments, depending on the spectral
index and the minimum energy cutoff. We discuss the constraint for the magnetic
field strength in the context of the models for the formation of magnetic
fields in cosmic filaments.Comment: Accepted for publication on MNRAS on June 5, 202
Frontier fields clusters: deep Chandra observations of the complex merger MACS~J1149.6+2223
The Hubble Space Telescope Frontier Fields cluster MACS J1149.6+2223 is one of the most complex merging clusters, believed to consist of four dark matter halos. We present results from deep (365 ks) Chandra observations of the cluster, which reveal the most distant cold front (z = 0.544) discovered to date. In the cluster outskirts, we also detect hints of a surface brightness edge that could be the bow shock preceding the cold front. The substructure analysis of the cluster identified several components with large relative radial velocities, thus indicating that at least some collisions occur almost along the line of sight. The inclination of the mergers with respect to the plane of the sky poses significant observational challenges at X-ray wavelengths. MACS J1149.6+2223 possibly hosts a steep-spectrum radio halo. If the steepness of the radio halo is confirmed, then the radio spectrum, combined with the relatively regular ICM morphology, could indicate that MACS J1149.6+2223 is an old merging cluster
The eROSITA Final Equatorial-Depth Survey (eFEDS): X-ray properties of Subaru optically-selected clusters
We present the results of a systematic X-ray analysis of optically rich
galaxy clusters detected by the Subaru HSC survey in the eROSITA eFEDS field.
Through a joint analysis of SRG/eROSITA and Subaru/HSC surveys, we aim to study
the dynamical status of the optically selected clusters and derive the cluster
scaling relations. The sample consists of 43 optically selected galaxy clusters
with a richness in . We systematically analyzed the X-ray
images and spectra using the eROSITA data. We identified the BCG using the
optical and far-infrared databases. We evaluated the cluster's dynamical status
by measuring the offset between the X-ray peak and BCG position, the gas
concentration, and the number of galaxy-density peaks. We studied the
luminosity-temperature and mass-luminosity relations based on eROSITA X-ray
spectra and HSC weak-lensing data analyses. Based on the these measurements,
the fraction of relaxed clusters is %, which is smaller than that of
the X-ray-selected cluster samples. After correcting for a selection bias due
to the richness cut, we obtained a shallow slope of , which is
consistent with the predictions of the self-similar model and the baseline
model incorporating a mass-concentration relation. The slope of
agrees with the above theoretical models and that of the
shear-selected clusters in the eFEDs field. Our analysis of high-richness
optical clusters yields a small fraction of relaxed clusters and a shallow
slope for the luminosity-temperature relation. This suggests that the average
X-ray properties of the optical clusters are likely to be different from those
observed in the X-ray samples. Thus, the joint eROSITA and HSC observations are
a powerful tool in extending the analysis to a larger sample and understanding
the selection effect with a view to establish cluster scaling relations.Comment: 12 pages, 4 figures, A&A accepted, minor correctio
Resolving the merging planck cluster plck G147.3-16.6 with gismo
The Planck satellite has recently completed an all-sky galaxy cluster survey exploiting the thermal Sunyaev-Zel'dovich (SZ) effect to locate some of the most massive systems observable. With a median redshift of , the clusters found by Planck at are proving to be exceptionally massive and/or disturbed systems. One notable Planck discovery at z = 0.645, PLCK G147.3-16.6, has an elongated core and hosts a radio halo, indicating it is likely in the process of merging. We present a 16.?5 resolution SZ observation of this high-z merger using the Goddard-IRAM Superconducting 2-Millimeter Observer, and compare it to X-ray follow-up observations with XMM-Newton. We find the SZ pressure substructure is offset from the core components seen in X-ray. We interpret this as possible line of sight temperature or density substructure due to the on-going merger
Slow dynamics and aging in a non-randomly frustrated spin system
A simple, non-disordered spin model has been studied in an effort to
understand the origin of the precipitous slowing down of dynamics observed in
supercooled liquids approaching the glass transition. A combination of Monte
Carlo simulations and exact calculations indicates that this model exhibits an
entropy vanishing transition accompanied by a rapid divergence of time scales.
Measurements of various correlation functions show that the system displays a
hierarchy of time scales associated with different degrees of freedom. Extended
structures, arising from the frustration in the system, are identified as the
source of the slow dynamics. In the simulations, the system falls out of
equilibrium at a temperature higher than the entropy-vanishing
transition temperature and the dynamics below exhibits aging as
distinct from coarsening. The cooling rate dependence of the energy is also
consistent with the usual glass formation scenario.Comment: 41 pages, 16 figures. Bibliography file is correcte
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