44 research outputs found
Introducing the TNG-Cluster Simulation: overview and physical properties of the gaseous intracluster medium
We introduce the new TNG-Cluster project, an addition to the IllustrisTNG
suite of cosmological magnetohydrodynamical simulations of galaxy formation.
Our objective is to significantly increase the statistical sampling of the most
massive and rare objects in the Universe: galaxy clusters with log(M_200c /
Msun) > 14.3 - 15.4 at z=0. To do so, we re-simulate 352 cluster regions drawn
from a 1 Gpc volume, thirty-six times larger than TNG300, keeping entirely
fixed the IllustrisTNG physical model as well as the numerical resolution. This
new sample of hundreds of massive galaxy clusters enables studies of the
assembly of high-mass ellipticals and their supermassive black holes (SMBHs),
brightest cluster galaxies (BCGs), satellite galaxy evolution and environmental
processes, jellyfish galaxies, intracluster medium (ICM) properties, cooling
and active galactic nuclei (AGN) feedback, mergers and relaxedness, magnetic
field amplification, chemical enrichment, and the galaxy-halo connection at the
high-mass end, with observables from the optical to radio synchrotron and the
Sunyaev-Zeldovich (SZ) effect, to X-ray emission, as well as their cosmological
applications. We present an overview of the simulation, the cluster sample,
selected comparisons to data, and a first look at the diversity and physical
properties of our simulated clusters and their hot ICM.Comment: Submitted to A&A. See companion papers today (Ayromlou, Lee, Lehle,
Rohr, Truong). Additional information and visuals are available on the
TNG-Cluster website at https://www.tng-project.org/cluster
X-ray inferred kinematics of the core ICM in Perseus-like clusters: insights from the TNG-Cluster simulation
The intracluster medium (ICM) of galaxy clusters encodes the impact of the
physical processes that shape these massive halos, including feedback from
central supermassive black holes (SMBHs). In this study we examine the gas
thermodynamics, kinematics, and the effects of SMBH feedback on the core of
Perseus-like galaxy clusters with a new simulation suite: TNG-Cluster. We first
make a selection of simulated clusters similar to Perseus based on total mass
and inner ICM properties, i.e. cool-core nature. We identify 30 Perseus-like
systems among the 352 TNG-Cluster halos at . Many exhibit thermodynamical
profiles and X-ray morphologies with disturbed features such as ripples,
bubbles and shock fronts that are qualitatively similar to X-ray observations
of Perseus. To study observable gas motions, we generate XRISM mock X-ray
observations and conduct a spectral analysis of the synthetic data. In
agreement with existing Hitomi measurements, TNG-Cluster predicts subsonic gas
turbulence in the central regions of Perseus-like clusters, with a typical
line-of-sight velocity dispersion of 200 km/s. This implies that turbulent
pressure contributes to the dominant thermal pressure. In TNG-Cluster,
such low (inferred) values of ICM velocity dispersion coexist with
high-velocity outflows and bulk motions of relatively small amounts of
super-virial hot gas, moving up to thousands of km/s. However, detecting these
outflows observationally may prove challenging due to their anisotropic nature
and projection effects. Driven by SMBH feedback, such outflows are responsible
for many morphological disturbances in the X-ray maps of cluster cores. They
also increase both the inferred, and intrinsic, ICM velocity dispersion. This
effect is somewhat stronger when velocity dispersion is measured from
higher-energy lines.Comment: 14 pages, 8 figures. Submitted to A&A, comments welcome. See the
TNG-Cluster website at www.tng-project.org/cluster
An Atlas of Gas Motions in the TNG-Cluster Simulation: from Cluster Cores to the Outskirts
Galaxy clusters are unique laboratories for studying astrophysical processes
and their impact on gas kinematics. Despite their importance, the full
complexity of gas motion within and around clusters remains poorly known. This
paper is part of a series presenting first results from the new TNG-Cluster
simulation, a suite of 352 massive clusters including the full cosmological
context, mergers, accretion, baryonic processes, feedback, and magnetic fields.
Studying the dynamics and coherence of gas flows, we find that gas motions in
cluster cores and intermediate regions are largely balanced between inflows and
outflows, exhibiting a Gaussian distribution centered at zero velocity. In the
outskirts, even the net velocity distribution becomes asymmetric, featuring a
double peak where the second peak reflects cosmic accretion. Across all cluster
regions, the resulting net flow distribution reveals complex gas dynamics.
These are strongly correlated with halo properties: at a given total cluster
mass, unrelaxed, late-forming halos with less massive black holes and lower
accretion rates exhibit a more dynamic behavior. Our analysis shows no clear
relationship between line-of-sight and radial gas velocities, suggesting that
line-of-sight velocity alone is insufficient to distinguish between inflowing
and outflowing gas. Additional properties, such as temperature, can help break
this degeneracy. A velocity structure function (VSF) analysis indicates more
coherent gas motion in the outskirts and more disturbed kinematics towards halo
centers. In all cluster regions, the VSF shows a slope close to the theoretical
models of Kolmogorov (1/3), except within 50 kpc of the cluster cores, where
the slope is significantly steeper. The outcome of TNG-Cluster broadly aligns
with observations of the VSF of multiphase gas across different scales in
galaxy clusters, ranging from 1 kpc to Megaparsec scales.Comment: Submitted to A&A. See the TNG-Cluster website at
https://www.tng-project.org/cluster
Weak-lensing mass bias in merging galaxy clusters
Although weak lensing (WL) is a powerful method to estimate a galaxy cluster
mass without any dynamical assumptions, a model bias can arise when the cluster
density profile departs from the assumed model profile. In a merging system,
the bias is expected to become most severe because the constituent halos
undergo significant structural changes. In this study, we investigate WL mass
bias in binary cluster mergers using a suite of idealized hydrodynamical
simulations. Realistic WL shear catalogs are generated by matching the source
galaxy properties, such as intrinsic shape dispersion, measurement noise,
source densities, etc., to those from Subaru and {\it Hubble Space Telescope}
observations. We find that, with the typical mass-concentration (-)
relation and the Navarro-Frenk-White (NFW) profile, the halo mass bias depends
on the time since the first pericenter passage and increases with the mass of
the companion cluster. The time evolution of the mass bias is similar to that
of the concentration, indicating that, to first order, the mass bias is
modulated by the concentration change. For a collision between two
clusters, the maximum bias amounts to . This
suggests that previous WL studies may have significantly overestimated the mass
of the clusters in some of the most massive mergers. Finally, we apply our
results to three merger cases: Abell 2034, MACS J1752.0+4440, and ZwCl
1856.8+6616, and report their mass biases at the observed epoch, as well as
their pre-merger masses, utilizing their merger shock locations as tracers of
the merger phases.Comment: 14 pages, 11 figures, submitted to Ap
Development of a high-density piezoelectric micromachined ultrasonic transducer array based on patterned aluminum nitride thin film
This study presents the fabrication and characterization of a piezoelectric micromachined ultrasonic transducer (pMUT; radius: 40 μm) using a patterned aluminum nitride (AlN) thin film as the active piezoelectric material. A 20 x 20 array of pMUTs using a 1 μm thick AlN thin film was designed and fabricated on a 2 x 2 mm2 footprint for a high fill factor. Based on the electrical impedance and phase of the pMUT array, the electromechanical coefficient was ~1.7% at the average resonant frequency of 2.82 MHz in air. Dynamic displacement of the pMUT surface was characterized by scanning laser Doppler vibrometry. The pressure output while immersed in water was 19.79 kPa when calculated based on the peak displacement at the resonant frequency. The proposed AlN pMUT array has potential applications in biomedical sensing for healthcare, medical imaging, and biometrics. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.1
Discovery of a Radio Relic in the Massive Merging Cluster SPT-CL 2023-5535 from the ASKAP-EMU PILOT SURVEY
The ASKAP-EMU survey is a deep wide-field radio continuum survey designed to
cover the entire southern sky and a significant fraction of the northern sky up
to . Here, we report a discovery of a radio relic in the merging
cluster SPT-CL 2023-5535 at z=0.23 from the ASKAP-EMU pilot 300 sq. deg survey
(800-1088 MHz). The deep high-resolution data reveal a Mpc-scale radio
halo elongated in the east-west direction, coincident with the intracluster
gas. The radio relic is located at the western edge of this radio halo
stretched Mpc in the north-south orientation. The integrated spectral
index of the radio relic within the narrow bandwidth is . Our weak-lensing
analysis shows that the system is massive () and composed of at least three subclusters. We suggest a scenario,
wherein the radio features arise from the collision between the eastern and
middle subclusters. Our discovery illustrates the effectiveness of the
ASKAP-EMU survey in detecting diffuse emissions in galaxy clusters and when
completed, the survey will greatly increase the number of merging cluster
detections with diffuse radio emissions.Comment: Accepted to Ap
Preservice Teachers\u27 Culturally Responsive Literacy Teaching Self-Efficacy Changes in the Field Experience
This study examined preservice teachers’ culturally responsive literacy teaching self-efficacy changes during the field experiences in relation to the sources of self-efficacy. I delved into the meanings under the theoretical frameworks of culturally responsive teaching and social cognitive theory. I explored 84 preservice teachers’ experiences over three semesters, who have been working with K-5 students from diverse backgrounds. Mixed-methods explanatory sequential design was adopted. In the quantitative phase, I administered a culturally responsive teaching self-efficacy survey before and after the field experiences. Additionally, sources of self-efficacy were studied using a source of self-efficacy inventory scale. Results of the quantitative study indicated that four different types of clusters exist: self-efficacy increased, self-efficacy high-stable, self-efficacy decreased, self-efficacy low-stable. In the qualitative phase, I investigated one preservice teacher from each cluster. This phase shed light on the reasons for the different self-efficacy change patterns among the preservice teachers. Findings from both phases (quantitative, qualitative) have implications: 1. It is crucial for both teacher educators and preservice teachers to understand their culturally responsive teaching self-efficacy and its changes. 2. Culturally responsive teaching self-efficacy and the sources of self-efficacy display reciprocal interaction. An awareness is critical of how preservice literacy teachers’ experiences in the field affects their culturally responsive teaching self-efficacy and other sources of self-efficacy. In light of the findings of the current study, teacher educators may wish to consider helping preservice teachers form informed and realistic culturally responsive teaching self-efficacy