scholarly journals The dynamical state of Abell 2399: a bullet-like cluster

2020 ◽  
Vol 498 (1) ◽  
pp. 835-849 ◽  
Author(s):  
Ana C C Lourenço ◽  
P A A Lopes ◽  
T F Laganá ◽  
R S Nascimento ◽  
R E G Machado ◽  
...  
Keyword(s):  
Galaxy Cluster ◽  
Gaussian Mixture ◽  
Substructure Search ◽  
Dynamical State ◽  
Main Cluster ◽  
Ram Pressure ◽  
Substructure Analysis ◽  
Merging Process ◽  
Hydrodynamical Simulations

ABSTRACT While there are many ways to identify substructures in galaxy clusters using different wavelengths, each technique has its own caveat. In this paper, we conduct a detailed substructure search and dynamical state characterization of Abell 2399, a galaxy cluster in the local Universe (z ∼ 0.0579), by performing a multiwavelength analysis and testing the results through hydrodynamical simulations. In particular, we apply a Gaussian mixture model to the spectroscopic data from SDSS, WINGS, and OmegaWINGS Surveys to identify substructures. We further use public XMM–Newton data to investigate the intracluster medium (ICM) thermal properties, creating temperature, metallicity, entropy, and pressure maps. Finally, we run hydrodynamical simulations to constrain the merger stage of this system. The ICM is very asymmetrical and has regions of temperature and pressure enhancement that evidence a recent merging process. The optical substructure analysis retrieves the two main X-ray concentrations. The temperature, entropy, and pressure are smaller in the secondary clump than in the main clump. On the other hand, its metallicity is considerably higher. This result can be explained by the scenario found by the hydrodynamical simulations where the secondary clump passed very near to the centre of the main cluster possibly causing the galaxies of that region to release more metals through the increase of ram-pressure stripping.

scholarly journals Halo cluster shapes: insights from simulated galaxies and ICL with prospects for weak lensing applications

2021 ◽  
Vol 508 (1) ◽  
pp. 1280-1295
Author(s):  
Elizabeth J Gonzalez ◽  
Cinthia Ragone-Figueroa ◽  
Carlos J Donzelli ◽  
Martín Makler ◽  
Diego García Lambas ◽  
...  
Keyword(s):  
Observational Studies ◽  
Semimajor Axis ◽  
Galaxy Cluster ◽  
Weak Lensing ◽  
Cluster Galaxy ◽  
Surface Mass ◽  
Cluster Shape ◽  
The Galaxy ◽  
Hydrodynamical Simulations ◽  
Intracluster Light

ABSTRACT We present a detailed study of the shapes and alignments of different galaxy cluster components using hydrodynamical simulations. We compute shape parameters from the dark matter (DM) distribution, the galaxy members and the intracluster light (ICL). We assess how well the DM cluster shape can be constrained by means of the identified galaxy member positions and the ICL. Further, we address the dilution factor introduced when estimating the cluster elongation using weak-lensing stacking techniques, which arises due to the misalignment between the total surface mass distribution and the distribution of luminous tracers. The dilution is computed considering the alignment between the DM and the brightest cluster galaxy, the galaxy members and the ICL. Our study shows that distributions of galaxy members and ICL are less spherical than the DM component, although both are well aligned with the semimajor axis of the latter. We find that the distribution of galaxy members hosted in more concentrated subhaloes is more elongated than the distribution of the DM. Moreover, these galaxies are better aligned with the DM component compared to the distribution of galaxies hosted in less concentrated subhaloes. We conclude that the positions of galaxy members can be used as suitable tracers to estimate the cluster surface density orientation, even when a low number of members is considered. Our results provide useful information for interpreting the constraints on the shapes of galaxy clusters in observational studies.

scholarly journals The Dynamical State of the Frontier Fields Galaxy Cluster Abell 370

2020 ◽  
Vol 900 (2) ◽  
pp. 151 ◽  
Author(s):  
Sandor M. Molnar ◽  
Shutaro Ueda ◽  
Keiichi Umetsu
Keyword(s):  
Galaxy Cluster ◽  
Dynamical State

scholarly journals First detection of a virial shock with SZ data: implication for the mass accretion rate of Abell 2319

2019 ◽  
Vol 622 ◽  
pp. A136 ◽  
Author(s):  
G. Hurier ◽  
R. Adam ◽  
U. Keshet
Keyword(s):  
Total Mass ◽  
Accretion Rate ◽  
Galaxy Cluster ◽  
Pressure Profile ◽  
Parametric Model ◽  
Large Radius ◽  
The Galaxy ◽  
The Hierarchical Structure ◽  
Shock Location ◽  
Hydrodynamical Simulations

Shocks produced by the accretion of infalling gas in the outskirts of galaxy clusters are expected in the hierarchical structure formation scenario, as found in cosmological hydrodynamical simulations. Here, we report the detection of a shock front at a large radius in the pressure profile of the galaxy cluster A2319 at a significance of 8.6σ, using Planck thermal Sunyaev-Zel’dovich data. The shock is located at (2.93 ± 0.05) × R500 and is not dominated by any preferential radial direction. Using a parametric model of the pressure profile, we derive a lower limit on the Mach number of the infalling gas, ℳ >  3.25 at 95% confidence level. These results are consistent with expectations derived from hydrodynamical simulations. Finally, we use the shock location to constrain the accretion rate of A2319 to Ṁ ≃ (1.4 ± 0.4) × 1014 M⊙ Gyr−1 for a total mass of M200 ≃ 1015 M⊙.

scholarly journals Isolation and characterization of a sequence type 25 carbapenem-resistant hypervirulent Klebsiella pneumoniae from the mid-south region of China

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Jun Li ◽  
Zi-Yan Huang ◽  
Ting Yu ◽  
Xiao-Yan Tao ◽  
Yong-Mei Hu ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Capsular Polysaccharide ◽  
Control Strategies ◽  
Virulence Gene ◽  
Sequence Type ◽  
Pfge Typing ◽  
Main Cluster ◽  
Carbapenem Resistant ◽  
Isolation And Characterization

Abstract Background The molecular characterization of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) isolates is not well studied. Our goal was to investigate the molecular epidemiology of CR-hvKP strains that were isolated from a Chinese hospital. Results All clinical carbapenem-resistant K. pneumoniae (CR-KP) isolates were collected and identified from patient samples between 2014 and 2017 from a Chinese hospital. The samples were subjected to screening for CR-hvKP by string test and the detection of the aerobactin gene. CR-hvKP isolates were further confirmed through neutrophil phagocytosis and a mice lethality assay. The CR-hvKP isolates were investigated for their capsular genotyping, virulence gene profiles, and the expression of carbapenemase genes by PCR and DNA sequencing. Multilocus sequence type (MLST) and pulsed-field gel electrophoresis (PFGE) were performed to exclude the homology of these isolates. Twenty strains were identified as CR-hvKP. These strains were resistant to imipenem and several other antibiotics, however, most were susceptible to amikacin. Notably, two isolates were not susceptible to tigecycline. Capsular polysaccharide synthesis genotyping revealed that 17 of the 20 CR-hvKP strains belonged to the K2 serotype, while the others belonged to serotypes other than K1, K2, K5, K20, and K57. The strains were found to be positive for 10 types of virulence genes and a variety of these genes coexisted in the same strain. Two carbapenemase genes were identified: blaKPC-2 (13/20) and blaNDM-1 (1/20). PFGE typing revealed eight clusters comprising isolates that belonged to MLST types ST25, ST11 and ST375, respectively. PFGE cluster A was identified as the main cluster, which included 11 isolates that belong to ST25 and mainly from ICU department. Conclusions Our findings suggest that hospital-acquired infections may contribute in part to the CR-hvKP strains identified in this study. It also suggests that ST25 CR-hvKP strain has a clonal distribution in our hospital. Therefore, effective surveillance and strict infection control strategies should be implemented to prevent outbreak by CR-hvKP strains in hospitals setting.

scholarly journals Quantitative Single-Cell Transcript Assessment of Biomarkers Supports Cellular Heterogeneity in the Bovine IVD

2019 ◽  
Vol 6 (2) ◽  
pp. 42 ◽  
Author(s):  
Kangning Li ◽  
Devin Kapper ◽  
Sumona Mondal ◽  
Thomas Lufkin ◽  
Petra Kraus
Keyword(s):  
In Situ Hybridization ◽  
Single Cell ◽  
Gaussian Mixture ◽  
Cellular Heterogeneity ◽  
Rna In Situ Hybridization ◽  
Ivd Degeneration

Severe and chronic low back pain is often associated with intervertebral disc (IVD) degeneration. While imposing a considerable socio-economic burden worldwide, IVD degeneration is also severely impacting on the quality of life of affected individuals. Cell-based regenerative medicine approaches have moved into clinical trials, yet IVD cell identities in the mature disc remain to be fully elucidated and tissue heterogeneity exists, requiring a better characterization of IVD cells. The bovine coccygeal IVD is an accepted research model to study IVD mechano-biology and disc homeostasis. Recently, we identified novel IVD biomarkers in the outer annulus fibrosus (AF) and nucleus pulposus (NP) of the mature bovine coccygeal IVD through RNA in situ hybridization (AP-RISH) and z-proportion test. Here we follow up on Lam1, Thy1, Gli1, Gli3, Noto, Ptprc, Scx, Sox2 and Zscan10 with fluorescent RNA in situ hybridization (FL-RISH) and confocal microscopy. This permits sub-cellular transcript localization and the addition of quantitative single-cell derived values of mRNA expression levels to our previous analysis. Lastly, we used a Gaussian mixture modeling approach for the exploratory analysis of IVD cells. This work complements our earlier cell population proportion-based study, confirms the previously proposed biomarkers and indicates even further heterogeneity of cells in the outer AF and NP of a mature IVD.

scholarly journals On the characterization of flowering curves using Gaussian mixture models

2016 ◽  
Vol 402 ◽  
pp. 75-88 ◽  
Author(s):  
Frédéric Proïa ◽  
Alix Pernet ◽  
Tatiana Thouroude ◽  
Gilles Michel ◽  
Jérémy Clotault
Keyword(s):  
Mixture Models ◽  
Gaussian Mixture Models ◽  
Gaussian Mixture

scholarly journals Particle re-acceleration and Faraday-complex structures in the RXC J1314.4-2515 galaxy cluster

2019 ◽  
Author(s):  
C Stuardi ◽  
A Bonafede ◽  
D Wittor ◽  
F Vazza ◽  
A Botteon ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Complex Structures ◽  
Very Large Array ◽  
Rotation Measure ◽  
Low Levels ◽  
Hydrodynamical Simulations ◽  
Polarization Fraction ◽  
The Magnetic Field

Abstract Radio relics are sites of electron (re)acceleration in merging galaxy clusters but the mechanism of acceleration and the topology of the magnetic field in and near relics are yet to be understood. We are carrying out an observational campaign on double relic galaxy clusters starting with RXC J1314.4-2515. With Jansky Very Large Array multi-configuration observations in the frequency range 1-4 GHz, we perform both spectral and polarization analyses, using the Rotation Measure synthesis technique. We use archival XMM-Newton observations to constrain the properties of the shocked region. We discover a possible connection between the activity of a radio galaxy and the emission of the eastern radio relic. In the northern elongated arc of the western radio relic, we detect polarized emission with an average polarization fraction of 31 % at 3 GHz and we derive the Mach number of the underlying X-ray shock. Our observations reveal low levels of fractional polarization and Faraday-complex structures in the southern region of the relic, which point to the presence of thermal gas and filamentary magnetic field morphology inside the radio emitting volume. We measured largely different Rotation Measure dispersion from the two relics. Finally, we use cosmological magneto-hydrodynamical simulations to constrain the magnetic field, viewing angle, and to derive the acceleration efficiency of the shock. We find that the polarization properties of RXC J1314.4-2515 are consistent with a radio relic observed at 70○ with respect to the line of sight and that efficient re-acceleration of fossil electrons has taken place.

scholarly journals The Three Hundred project: shapes and radial alignment of satellite, infalling, and backsplash galaxies

2020 ◽  
Vol 495 (3) ◽  
pp. 3002-3013 ◽  
Author(s):  
Alexander Knebe ◽  
Matías Gámez-Marín ◽  
Frazer R Pearce ◽  
Weiguang Cui ◽  
Kai Hoffmann ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Cluster Radius ◽  
Dynamical State ◽  
The Galaxy ◽  
Radial Orbit ◽  
Galaxy Halo ◽  
Satellite Galaxies

ABSTRACT Using 324 numerically modelled galaxy clusters, we investigate the radial and galaxy–halo alignment of dark matter subhaloes and satellite galaxies orbiting within and around them. We find that radial alignment depends on distance to the centre of the galaxy cluster but appears independent of the dynamical state of the central host cluster. Furthermore, we cannot find a relation between radial alignment of the halo or galaxy shape with its own mass. We report that backsplash galaxies, i.e. objects that have already passed through the cluster radius but are now located in the outskirts, show a stronger radial alignment than infalling objects. We further find that there exists a population of well radially aligned objects passing very close to the central cluster’s centre that were found to be on highly radial orbit.

scholarly journals Optical validation and characterization of Planck PSZ2 sources at the Canary Islands observatories

2019 ◽  
Vol 631 ◽  
pp. A148
Author(s):  
A. Aguado-Barahona ◽  
R. Barrena ◽  
A. Streblyanska ◽  
A. Ferragamo ◽  
J. A. Rubiño-Martín ◽  
...  
Keyword(s):  
Dust Emission ◽  
Galaxy Cluster ◽  
Clear Correlation ◽  
First Year ◽  
Isaac Newton ◽  
La Palma ◽  
Sky Survey ◽  
Spectroscopic Information ◽  
Second Year

Context. The second legacy catalog of Planck Sunyaev–Zeldovich (SZ) sources, hereafter PSZ2, provides the largest galaxy cluster sample selected by means of the SZ signature of the clusters in a full sky survey. In order to fully characterize this PSZ2 sample for cosmological studies, all the members should be validated and the physical properties of the clusters, including mass and redshift, should be derived. However, at the time of its publication, roughly 21% of the 1653 PSZ2 members had no known counterpart at other wavelengths. Aims. Here, we present the second and last year of observations of our optical follow-up program 128-MULTIPLE-16/15B (hereafter LP15), which has been developed with the aim of validating all the unidentified PSZ2 sources in the northern sky with declinations higher than −15° that have no correspondence in the first Planck catalog PSZ1. The description of the program and the first year of observations have been presented previously. Methods. The LP15 program was awarded 44 observing nights that were spread over two years with the Isaac Newton Telescope (INT), the Telescopio Nazionale Galileo (TNG), and the Gran Telescopio Canarias (GTC), all at Roque de los Muchachos Observatory (La Palma). Following the same method as described previously, we performed deep optical imaging for more than 200 sources with the INT and spectroscopy for almost 100 sources with the TNG and GTC at the end of the LP15 program. We adopted robust confirmation criteria based on velocity dispersion and richness estimates for the final classification of the new galaxy clusters as the optical counterparts of the PSZ2 detections. Results. Here, we present the observations of the second year of LP15, as well as the final results of the program. The full LP15 sample comprises 190 previously unidentified PSZ2 sources. Of these, 106 objects were studied before, while the remaining sample (except for 6 candidates) has been completed in the second year and is discussed here. In addition to the LP15 sample, we here study 42 additional PSZ2 objects that were originally validated as real clusters because they matched a WISE or PSZ1 counterpart, but they had no measured spectroscopic redshift. In total, we confirm the optical counterparts for 81 PSZ2 sources after the full LP15 program, 55 of them with new spectroscopic information. Forty of these 81 clusters are presented in this paper. After the LP15 observational program the purity of the PSZ2 catalog has increased from 76.7% originally to 86.2%. In addition, we study the possible reasons for false detection, and we report a clear correlation between the number of unconfirmed sources and galactic thermal dust emission.

Characterization of optimal input distributions for Gaussian-mixture noise channels

2015 ◽  
Author(s):  
Hung V. Vu ◽  
Nghi H. Tran ◽  
Mustafa Cenk Gursoy ◽  
Tho Le-Ngoc ◽  
S. I. Hariharan
Keyword(s):  
Gaussian Mixture ◽  
Optimal Input
Sign in / Sign up

Export Citation Format

Share Document