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Articles de revues sur le sujet « Intra Cluster Medium »

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Auteur : Grafiati
Publié le 11 mars 2023

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1

Domainko, Wilfried, Wolfgang Kapferer, Sabine Schindler, Eelco van Kampen, Stefan Kimeswenger et Maximilian Ruffert. « The Chemical Evolution of the Intra-Cluster Medium ». Symposium - International Astronomical Union 217 (2004) : 464–65. http://dx.doi.org/10.1017/s0074180900198195.

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We present numerical simulations of the dynamical and chemical evolution of galaxy clusters. from X-ray spectra it is evident that the Intra-Cluster Medium (ICM) is abundant in metals. As heavy elements are only produced in stars the processed material must have been ejected by cluster galaxies into the ICM. Several different mechanisms for interaction between the cluster galaxies and the ICM are possible but their efficiency of metal enrichment of the cluster and their time evolution are still not known. Suggested processes which remove enriched material from the galaxies are ram-pressure stripping, galactic winds, superwinds driven by starburst activity and jets from active galaxies. First results of high resolution hydrodynamic simulations on cluster scales are presented to investigate the effect of these different pollution mechanisms.
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2

Schindler, S. « Metal Enrichment in the Intra-Cluster Medium ». EAS Publications Series 24 (2007) : 121–32. http://dx.doi.org/10.1051/eas:2007019.

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3

Moretti, A., L. Portinari et C. Chiosi. « Chemical evolution of the intra-cluster medium ». Astronomy & ; Astrophysics 408, no 2 (septembre 2003) : 431–53. http://dx.doi.org/10.1051/0004-6361:20031012.

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4

Bignamini, A., P. Tozzi, S. Borgani, S. Ettori et P. Rosati. « Intra cluster medium properties and AGN distribution in high-zRCS clusters ». Astronomy & ; Astrophysics 489, no 3 (1 août 2008) : 967–79. http://dx.doi.org/10.1051/0004-6361:200809437.

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5

Bonafede, Annalisa, Chiara Stuardi, Federica Savini, Franco Vazza et Marcus Brüggen. « Constraining magnetic fields in galaxy clusters ». Proceedings of the International Astronomical Union 14, A30 (août 2018) : 299–302. http://dx.doi.org/10.1017/s1743921319004459.

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AbstractMagnetic fields originate small-scale instabilities in the plasma of the intra-cluster medium, and may have a key role to understand particle acceleration mechanisms. Recent observations at low radio frequencies have revealed that synchrotron emission from galaxy clusters is more various and complicated than previously thought, and new types of radio sources have been observed. In the last decade, big steps forward have been done to constrain the magnetic field properties in clusters thanks to a combined approach of polarisation observations and numerical simulations that aim to reproduce Faraday Rotation measures of sources observed through the intra-cluster medium. In this contribution, I will review the results on magnetic fields reached in the last years, and I will discuss the assumptions that have been done so far in light of new results obtained from cosmological simulations. I will also discuss how the next generation of radio instruments, as the SKA, will help improving our knowledge of the magnetic field in the intra-cluster medium.
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6

Cucchetti, E., N. Clerc, E. Pointecouteau, P. Peille et F. Pajot. « Towards mapping turbulence in the intra-cluster medium ». Astronomy & ; Astrophysics 629 (septembre 2019) : A144. http://dx.doi.org/10.1051/0004-6361/201935677.

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X-ray observations of the hot gas filling the intra-cluster medium (ICM) provide a wealth of information on the dynamics of clusters of galaxies. The global equilibrium of the ICM is believed to be ensured by non-thermal and thermal pressure support sources, among which gas movements and the dissipation of energy through turbulent motions. Accurate mapping of turbulence using X-ray emission lines is challenging due to the lack of spatially resolved spectroscopy. Only future instruments such as the X-ray Integral Field Unit (X-IFU) on Athena will have the spatial and spectral resolution to quantitatively investigate the ICM turbulence over a broad range of spatial scales. Powerful diagnostics for these studies are line shift and the line broadening maps, and the second-order structure function. When estimating these quantities, instruments will be limited by uncertainties of their measurements, and by the sampling variance (also known as cosmic variance) of the observation. Here, we extend the formalism started in our companion Paper I to include the effect of statistical uncertainties of measurements in the estimation of these line diagnostics, in particular for structure functions. We demonstrate that statistics contribute to the total variance through different terms, which depend on the geometry of the detector, the spatial binning and the nature of the turbulent field. These terms are particularly important when probing the small scales of the turbulence. An application of these equations is performed for the X-IFU, using synthetic turbulent velocity maps of a Coma-like cluster. Results are in excellent agreement with the formulas both for the structure function estimation (≤3%) and its variance (≤10%). The expressions derived here and in Paper I are generic, and ensure an estimation of the total errors in any X-ray measurement of turbulent structure functions. They also open the way for optimisations in the upcoming instrumentation and in observational strategies.
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Kotecha, Sachin, Charlotte Welker, Zihan Zhou, James Wadsley, Katarina Kraljic, Jenny Sorce, Elena Rasia et al. « Cosmic filaments delay quenching inside clusters ». Monthly Notices of the Royal Astronomical Society 512, no 1 (10 février 2022) : 926–44. http://dx.doi.org/10.1093/mnras/stac300.

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ABSTRACT We investigate how large-scale cosmic filaments impact the quenching of galaxies within one virial radius of 324 simulated clusters from The Three Hundred project. We track cosmic filaments with the versatile, observation-friendly program DisPerSE and identify haloes hosting galaxies with VELOCIRaptor. We find that cluster galaxies close to filaments tend to be more star forming, bluer, and contain more cold gas than their counterparts further away from filaments. This effect is recovered at all stellar masses. This is in stark contrast with galaxies residing outside of clusters, where galaxies close to filaments show clear signs of density related pre-processing. We first show that the density contrast of filaments is reduced inside the intra-cluster medium. Moreover, examination of flows around and into cluster galaxies shows that the gas flows in intra-cluster filaments are colder and tend to stream along with galaxies in their midst, partially shielding them from strangulation by the hot, dense intra-cluster medium. This also preserves accretion on to satellites and limit ram pressure.
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8

Schindler, S., W. Kapferer, W. Domainko, M. Mair, E. van Kampen, T. Kronberger, S. Kimeswenger, M. Ruffert, O. Mangete et D. Breitschwerdt. « Metal enrichment processes in the intra-cluster medium ». Astronomy & ; Astrophysics 435, no 2 (29 avril 2005) : L25—L28. http://dx.doi.org/10.1051/0004-6361:200500107.

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9

Puchwein, E., et M. Bartelmann. « Three-dimensional reconstruction of the intra-cluster medium ». Astronomy & ; Astrophysics 455, no 3 (16 août 2006) : 791–801. http://dx.doi.org/10.1051/0004-6361:20054717.

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10

Clerc, Nicolas, Edoardo Cucchetti, Etienne Pointecouteau et Philippe Peille. « Towards mapping turbulence in the intra-cluster medium ». Astronomy & ; Astrophysics 629 (septembre 2019) : A143. http://dx.doi.org/10.1051/0004-6361/201935676.

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Context. X-ray observations of galaxy clusters provide insights into the nature of gaseous turbulent motions, their physical scales, and the fundamental processes to which they are related. Spatially-resolved, high-resolution spectral measurements of X-ray emission lines provide diagnostics on the nature of turbulent motions in emitting atmospheres. Since they are acting on scales comparable to the size of the objects, the uncertainty on these physical parameters is limited by the number of observational measurements, through sample variance. Aims. We propose a different and complementary approach to repeating numerical simulations for the computation of sample variance (i.e. Monte-Carlo sampling) by introducing new analytical developments for lines diagnosis. Methods. We considered the model of a “turbulent gas cloud”, consisting in isotropic and uniform turbulence described by a universal Kolmogorov power-spectrum with random amplitudes and phases in an optically thin medium. Following a simple prescription for the four-term correlation of Fourier coefficients, we derived generic expressions for the sample mean and variance of line centroid shift, line broadening, and projected velocity structure function. We performed a numerical validation based on Monte-Carlo simulations for two popular models of gas emissivity based on the β-model. Results. Generic expressions for the sample variance of line centroid shifts and broadening in arbitrary apertures are derived and match the simulations within their range of applicability. Generic expressions for the mean and variance of the structure function are provided and verified against simulations. An application to the Athena/X-IFU (Advanced Telescope for High-ENergy Astrophysics/X-ray Integral Field Unit) and XRISM/Resolve (X-ray Imaging and Spectroscopy Mission) instruments forecasts the potential of sensitive, spatially-resolved spectroscopy to probe the inertial range of turbulent velocity cascades in a Coma-like galaxy cluster. Conclusions. The formulas provided are of generic relevance and can be implemented in forecasts for upcoming or current X-ray instrumentation and observing programmes.
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11

Werner, N., F. Durret, T. Ohashi, S. Schindler et R. P. C. Wiersma. « Observations of Metals in the Intra-Cluster Medium ». Space Science Reviews 134, no 1-4 (février 2008) : 337–62. http://dx.doi.org/10.1007/s11214-008-9320-9.

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12

Bourdin, H., et P. Mazzotta. « Temperature structure of the intra-cluster medium within relaxed clusters of galaxies ». EAS Publications Series 20 (2006) : 267–68. http://dx.doi.org/10.1051/eas:2006083.

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13

Elbaz, D., et L. Vigroux. « Time Scales for Galaxy Formation and Intra-Cluster Medium Enrichment ». Symposium - International Astronomical Union 171 (1996) : 370. http://dx.doi.org/10.1017/s0074180900232890.

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Recent observations with ASCA (Mushotzky 94, New Horizon of X-Ray Astron.-1st Results from ASCA) have confirmed the prediction (Arnaud et al. 92, A&A 254, 49; Elbaz et al. 95, to appear in A&A) that the Fe present in the intra-cluster medium (ICM) is mainly due to SNII and not SNIa: α-elements (O, Ne, Si, S) are overabundant with respect to Fe. To account for the large Fe mass present in galaxy clusters as well as these abundances ratios, one must consider that the IMF was different in the past, favouring high-mass stars. Moreover, the simplest way to eject the enriched ISM into the ICM is to consider that the same high-mass stars that were responsible for the Fe enrichment have also driven a galactic wind in young E/SO's.
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14

Tozzi, P., S. Ettori, P. Rosati et S. Borgani. « Properties of the intra cluster medium at high redshift ». Nuclear Physics B - Proceedings Supplements 132 (juin 2004) : 48–53. http://dx.doi.org/10.1016/j.nuclphysbps.2004.04.006.

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Akter, M. S., A. Biswas, S. S. Siddique, S. Hossain et N. A. Ivy. « Estimation of Genetic Diversity in Onion (Allium cepa L.) ». Agriculturists 13, no 1 (24 janvier 2016) : 26–34. http://dx.doi.org/10.3329/agric.v13i1.26545.

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The experiment was conducted at the field laboratory of the Department of Genetics and Plant Breeding, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during November 2008 to March 2009 to estimate the genetic diversity of exotic and local onion. Ten genotypes of onion were evaluated for 16 characters in a randomized complete block design to study the genetic divergence through multivariate analysis. Ten genotypes formed three clusters. Cluster III contained maximum number of five genotypes. Cluster I and II contained three and two genotypes, respectively. The inter cluster distance was larger than the intra cluster distances. The inter cluster distance was maximum between the cluster II and III (6.336) and minimum between the cluster I and II (3.876). The intra cluster distance in the entire three clusters was more or less low, indicating that genotypes within the same cluster were closely related. Considering clustered distance and cluster mean, the intra cluster distance revealed that the genotypes Indian big (G1) and Patnai pink (G5) from the cluster II and genotypes Taherpuri, Indian medium (G1), Big single bulb (G7), Big double bulb (G8), Small single bulb (G9) and Small double bulb (G10) from the cluster III may be selected as parents for future breeding program.The Agriculturists 2015; 13(1) 26-34
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16

Neumann, D. M. « Tracing the X-ray emitting intra-cluster medium of clusters of galaxies beyondR200 ». EAS Publications Series 20 (2006) : 179–82. http://dx.doi.org/10.1051/eas:2006067.

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17

Zaman, MA, et MA Islam. « Genetic Diversity In Exotic Maize (Zea mays L.) Hybrids ». Bangladesh Journal of Agricultural Research 38, no 2 (28 juillet 2013) : 335–41. http://dx.doi.org/10.3329/bjar.v38i2.15894.

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An experiment in alpha lattice design with three replication including 39 exotic maize hybrids was conducted at the Research farm of Regional Agricultural Research Station, BARI, Ishuardi, Pabna during Rabi season 2010-11 for analysis the genetic divergence in exotic maize hybrids. The genotypes were grouped in to seven clusters. Cluster VI comprised the maximum genotypes (13) indicating overall genetic similarity among them. The minimum genotype (1) was contained in the cluster III and V. The highest inter-cluster distance was observed between cluster V and III followed by cluster I and III and cluster III and VII suggesting wide diversity between them and the genotypes in these cluster could be used in hybridization program for obtaining a wide spectrum of variation among the segregates. The highest intra-cluster distance was observed in cluster VII and the cluster III and V were contained only one genotype and hence, their intra cluster distance was zero. The mean values of cluster IV recorded the highest yield per hectare (11.60 ton/ha) with medium plant height, days to maturity, days to 50% tasseling, silking and shelling percentage. Selection on the basis of plant aspect and ear aspect the genotypes of cluster III ranked first but plant height was high with medium seed size, medium yield, medium shelling percentage and also in late in case of maturity. The mean values of cluster V shown overall medium in case of yield and all yield contributing characters. Qualitative characters contribute maximum towards genetic divergence. Therefore, the genotypes from cluster III, V and VI could be utilized as source materials for getting desirable new recombinants with early maturity and higher yield. Bangladesh J. Agril. Res. 38(2): 335-341, June 2013 DOI: http://dx.doi.org/10.3329/bjar.v38i2.15894
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18

Domainko, Wilfried, Wolfgang Kapferer, Sabine Schindler, Eelco van Kampen, Stefan Kimeswenger, Magdalena Mair, Thomas Kronberger, Maximilian Ruffert et Ontonio E. Mangete. « Metal enrichment of the intra-cluster medium : ram-pressure stripping of cluster galaxies ». Advances in Space Research 36, no 4 (janvier 2005) : 685–88. http://dx.doi.org/10.1016/j.asr.2004.12.061.

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19

P. Bassino, Lilia, Sergio A. Cellone et Juan C. Forte. « A Search for Globular Clusters in the Surroundings of Dwarf Galaxies in Fornax : Intracluster Globulars ? » Symposium - International Astronomical Union 207 (2002) : 345–47. http://dx.doi.org/10.1017/s0074180900224030.

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We present the results of a search for globular clusters in the surroundings of 15 low surface brightness dwarf galaxies in the Fornax cluster, on CCD images in the C and T1 bands. Globular cluster candidates show a clear bimodal color distribution. Their surface density distribution shows no concentration towards the respective dwarf galaxies but it does show concentration towards the center of the Fornax cluster. We suggest that the potential globular clusters might not be bound to the dwarf galaxies, but might instead belong to the intra-cluster medium.
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Combes, Françoise. « Efficiency of Stripping Mechanisms ». Symposium - International Astronomical Union 217 (2004) : 440–51. http://dx.doi.org/10.1017/s007418090019816x.

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There are several physical processes to remove gas from galaxies in clusters, with subsequent starvation and star formation quenching: tidal interactions between galaxies, or tidal stripping from the cluster potential itself, interactions with the hot intra-cluster medium (ICM) through ram pressure, turbulent or viscous stripping, or also outflows from star formation of nuclear activity, We review the observational evidence for all processes, and numerical simulations of galaxies in clusters which support the respective mechanisms. This allows to compare their relative efficiencies, all along cluster formation.
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21

Nulsen, Paul E. J., Brian R. McNamara, Laurence P. David et Michael W. Wise. « X-ray Cavities and Cooling Flows ». Highlights of Astronomy 13 (2005) : 307–11. http://dx.doi.org/10.1017/s1539299600015859.

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AbstractRecent data have radically altered the X-ray perspective on cooling flow clusters. X-ray spectra show that very little of the hot intra-cluster medium is cooler than about 1 keV, despite having short cooling times. In an increasing number of cooling flow clusters, the lobes of a central radio source are found to have created cavities in the hot gas. Generally, the cavities are not overpressured relative to the intra-cluster gas, but act as buoyant bubbles of radio emitting plasma that drive circulation as they rise, mixing and heating the intra-cluster gas. All this points to the radio source, i.e., an active galactic nucleus, as the heat source that prevents gas from cooling to low temperatures. However, heating due to bubbles alone seems to be insufficient, so the energetics of cooling flows remain obscure. We briefly review the data and theory supporting this view and discuss the energetics of cooling flows.
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Leccardi, A., M. Rossetti et S. Molendi. « Thermo-dynamic and chemical properties of the intra-cluster medium ». Astronomy and Astrophysics 510 (février 2010) : A82. http://dx.doi.org/10.1051/0004-6361/200913094.

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23

Mernier, F., J. de Plaa, C. Pinto, J. S. Kaastra, P. Kosec, Y. Y. Zhang, J. Mao et N. Werner. « Origin of central abundances in the hot intra-cluster medium ». Astronomy & ; Astrophysics 592 (août 2016) : A157. http://dx.doi.org/10.1051/0004-6361/201527824.

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24

Gilkis, Avishai, et Noam Soker. « Heating the intra-cluster medium perpendicular to the jets axis ». Monthly Notices of the Royal Astronomical Society 427, no 2 (19 novembre 2012) : 1482–89. http://dx.doi.org/10.1111/j.1365-2966.2012.22085.x.

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25

Mernier, F., J. de Plaa, C. Pinto, J. S. Kaastra, P. Kosec, Y. Y. Zhang, J. Mao, N. Werner, O. R. Pols et J. Vink. « Origin of central abundances in the hot intra-cluster medium ». Astronomy & ; Astrophysics 595 (novembre 2016) : A126. http://dx.doi.org/10.1051/0004-6361/201628765.

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Portinari, L., J. Sommer-Larsen et A. D. Romeo. « Cluster Formation with Chemical and Energy Feedback ». Symposium - International Astronomical Union 217 (2004) : 328–30. http://dx.doi.org/10.1017/s0074180900197864.

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We present fully cosmological, hydrodynamical simulations of clusters of galaxies, including star formation, supernova feedback, chemical enrichment and metal-dependent cooling. We investigate the relation between feedback, metal enrichment of the intra-cluster medium (ICM) and the distribution of baryons in the various phases (cold gas+stars and hot ICM) at varying Initial Mass Function and wind efficiency.
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Wu, Kinwah, Melanie Johnston-Hollitt et Richard Hunstead. « Radio Halo and Relic Sources in Galaxy Clusters ». Highlights of Astronomy 13 (2005) : 312–16. http://dx.doi.org/10.1017/s1539299600015860.

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AbstractWe review briefly the general properties of halo and relic sources in galaxy clusters. We also present a polarized radiative transfer algorithm which is useful for calculations of polarized radio emission from halos, relics and active galaxies in a magnetized intra-cluster medium.
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28

Azam, M. G. Azam, U. K. Sarker Sarker, M. A. K. Mian Mian, B. R. Banik Banik et M. Z. A. Talukder. « GENETIC DIVERGENCE ON QUANTITATIVE CHARACTERS OF EXOTIC MAIZE INBREDS (Zea mays L.) ». Bangladesh Journal of Plant Breeding and Genetics 26, no 2 (24 juin 2015) : 09–14. http://dx.doi.org/10.3329/bjpbg.v26i2.23844.

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Forty nine CIMMYT, India Maize inbred lines were characterized based on some morphological traits and grain yield. Genetic divergences of inbred lines of maize were estimated using D2 and principal component analysis. The genotypes under study fell into five clusters. The inter cluster distance were higher than intra cluster distance suggesting wider genetic diversity among the genotypes of different groups. The maximum intra cluster value was observed in cluster IV and minimum in cluster V. The inter cluster D2 values revealed that the maximum distance among the cluster. The highest inter cluster distance was observed between cluster II & I and the lowest inter cluster distance was illustrated in cluster III & I. The cluster means were higher for days to 50% tasseling, days to 50% sillking, plant height, ear height, cob length, number of rows per cob, number of grains per row in cluster IV; cob diameter and grain yield per plant was found higher in cluster II. It is expected that crossing of inbred lines belonging high to medium D2 values tend to produce high heterosis for yield.
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29

Ulmer, M. P., R. G. Cruddace, E. Fenimore, W. A. Snyder et G. Fritz. « Elemental Abundances and Temperature Distributions in the Intra-cluster Medium of the Perseus Cluster ». Symposium - International Astronomical Union 124 (1987) : 523–26. http://dx.doi.org/10.1017/s0074180900159492.

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Temperatures and iron abundances in two distinct regions of the Perseus Cluster, based on X-ray observations made with SPARTAN 1, are reported. Iron abundance values relative to solar are and , and the temperatures are and for the regions 0′ to 5′ and 6′ to 20′ from the cluster center, respectively. The uncertainties are 90% confidence.
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Elbaz, D. « Infrared Observations of Galaxy Clusters ». Highlights of Astronomy 11, no 2 (1998) : 1128–30. http://dx.doi.org/10.1017/s1539299600019754.

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The evolution of galaxy clusters from their formation due to the merging of sub structures, the bulk of star formation and subsequent chemical enrichment of the intra-cluster medium, is expected to be quite recent (z<l-2) in the hierarchical clustering scenario (White & Frenk 1991).
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Rossich Molina, Estefania, et Tamar Stein. « The Effect of Cluster Size on the Intra-Cluster Ionic Polymerization Process ». Molecules 26, no 16 (7 août 2021) : 4782. http://dx.doi.org/10.3390/molecules26164782.

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Polyaromatic hydrocarbons (PAHs) are widespread in the interstellar medium (ISM). The abundance and relevance of PAHs call for a clear understanding of their formation mechanisms, which, to date, have not been completely deciphered. Of particular interest is the formation of benzene, the basic building block of PAHs. It has been shown that the ionization of neutral clusters can lead to an intra-cluster ionic polymerization process that results in molecular growth. Ab-initio molecular dynamics (AIMD) studies in clusters consisting of 3–6 units of acetylene modeling ionization events under ISM conditions have shown maximum aggregation of three acetylene molecules forming bonded C6H6+ species; the larger the number of acetylene molecules, the higher the production of C6H6+. These results lead to the question of whether clusters larger than those studied thus far promote aggregation beyond three acetylene units and whether larger clusters can result in higher C6H6+ production. In this study, we report results from AIMD simulations modeling the ionization of 10 and 20 acetylene clusters. The simulations show aggregation of up to four acetylene units producing bonded C8H8+. Interestingly, C8H8+ bicyclic species were identified, setting a precedent for their astrochemical identification. Comparable reactivity rates were shown with 10 and 20 acetylene clusters.
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32

Neumann, D. M. « Tracing the X-ray emitting intra-cluster medium of clusters of galaxies beyondr$\mathsf{_{200}}$ ». Astronomy & ; Astrophysics 439, no 2 (29 juillet 2005) : 465–77. http://dx.doi.org/10.1051/0004-6361:20053015.

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Pipino, Antonio, Francesca Matteucci, Stefano Borgani et Andrea Biviano. « SNe heating and the chemical evolution of the intra-cluster medium ». New Astronomy 7, no 5 (juillet 2002) : 227–47. http://dx.doi.org/10.1016/s1384-1076(02)00136-7.

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34

Hattori, M. « A Metal Enriched Dark Cluster of Galaxies at Z = 1 ». Symposium - International Astronomical Union 187 (2002) : 129–38. http://dx.doi.org/10.1017/s0074180900113841.

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Looking for and studying very distant galaxy clusters, clusters at z > 1, are one of the prime subjects of the modern observational cosmology. If the metallicity of the hot intra-cluster medium in very distant galaxy clusters is measured for example, it provides fruitful informations for us to understand the formation and evolution of galaxies. However, difficulty of the study is that there is few confirmed very distant galaxy clusters yet. We first have to search for very distant clusters but it requires very deep observations. A random selection of sky is not practical. We have to select the sky. In this article, it is demonstrated that missing lens problem has close connection with very distant cluster of galaxies and dark lens searches could open a new window for studying very distant cluster of galaxies.
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Hirashita, H., S. Mineshige, K. Shibata et R. Matsumoto. « The Supply of Magnetic Fields from a cD Galaxy to Intra-Cluster Space ». Symposium - International Astronomical Union 188 (1998) : 306–7. http://dx.doi.org/10.1017/s007418090011527x.

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Intra-cluster spaces are filled with intra-cluster medium (ICM), whose typical temperature and density are TICM ~ 107.5 K and nICM ~ 10−3 cm−3, respectively (e.g., Sarazin 1988). Recent Faraday rotation measurements have revealed the existence of magnetic fields in ICM with few − 10 μG (e.g., Ge & Owen 1993). In ICM, the plasma β (the ratio of gas pressure to magnetic pressure) is almost “equipartition” value as follows:
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Kirk, J. G., P. Duffy et R. O. Dendy. « Electron Transport in the Coma Cluster ». Symposium - International Astronomical Union 175 (1996) : 339–40. http://dx.doi.org/10.1017/s0074180900081018.

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The inner regions of the Coma cluster of galaxies contain a source of diffuse synchrotron emission (‘Coma C’) which has a linear dimension of at least 500 kpc. There has been interest in the question of where the relativistic electrons responsible for this emission originate, and how they are transported through the intra-cluster medium (Tribble, 1993). It is widely thought that one or more of the radio galaxies in the centre of the cluster provides a likely source for particles which then diffuse out into the halo (Giovannini et al., 1993); a process which depends critically on the structure of this field in the intra-cluster medium. Recent observations of the emission from NGC4869 (Feretti et al., 1995), which occupies a central position in the Coma cluster, indicate the presence of a magnetic field which is both stronger (B ≈ 8μ G) and tangled on much shorter scales ≲ 1 kpc than had been thought previously (Kim et al., 1990). These new results suggest not only a shorter cooling time for energetic electrons, but also a slower rate of diffusive transport. In this paper we show the constraints that the new observations place on transport theories of the relativistic electrons.
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37

Balestra, I., P. Tozzi, S. Ettori, P. Rosati, S. Borgani, V. Mainieri C. Norman et M. Viola. « Tracing the evolution in the iron content of the intra-cluster medium ». Astronomy & ; Astrophysics 462, no 2 (2 novembre 2006) : 429–42. http://dx.doi.org/10.1051/0004-6361:20065568.

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38

Santos-Lima, R., E. M. de Gouveia Dal Pino, A. Lazarian, G. Kowal et D. Falceta-Gonçalves. « Dynamo in the Intra-Cluster Medium : Simulation of CGL-MHD Turbulent Dynamo ». Proceedings of the International Astronomical Union 6, S274 (septembre 2010) : 482–84. http://dx.doi.org/10.1017/s1743921311007563.

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AbstractThe standard magnetohydrodynamic (MHD) description of the plasma in the hot, magnetized gas of the intra-cluster (ICM) medium is not adequate because it is weakly collisional. In such collisionless magnetized gas, the microscopic velocity distribution of the particles is not isotropic, giving rise to kinetic effects on the dynamical scales. These kinetic effects could be important in understanding the turbulence as well as the amplification and maintenance of the magnetic fields in the ICM. It is possible to formulate fluid models for collisonless or weakly collisional gas by introducing modifications in the MHD equations. These models are often referred as kinetic MHD (KMHD). Using a KMHD model based on the CGL-closure, which allows the adiabatic evolution of the two components of the pressure tensor (the parallel and perpendicular components with respect to the local magnetic field), we performed 3D numerical simulations of forced turbulence in order to study the amplification of an initially weak seed magnetic field. We found that the growth rate of the magnetic energy is comparable to that of the ordinary MHD turbulent dynamo, but the magnetic energy saturates in a level smaller than that of the MHD case. We also found that a necessary condition for the dynamo to operate is to impose constraints on the anisotropy of the pressure.
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39

Shang, Cien, et S. Peng Oh. « Probing gas motions in the intra-cluster medium : a mixture model approach ». Monthly Notices of the Royal Astronomical Society 426, no 4 (22 octobre 2012) : 3435–54. http://dx.doi.org/10.1111/j.1365-2966.2012.21897.x.

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40

Leon, S., J. Perea, A. Del Olmo, E. Athanassoula, G. Bergond, G. Meylan et C. Garcia Gomez. « Evolution of Globular Cluster Populations in Compact Galaxy Groups ». Highlights of Astronomy 13 (2005) : 204. http://dx.doi.org/10.1017/s1539299600015707.

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AbstractThe redistribution of globular clusters within compact groups of galaxies is followed through N-body simulations. Particular emphasis is given to the globular clusters released in the Intra-Group Medium (IGM) and to the final configuration of the evolution.
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41

Kapferer, W., T. Kronberger, W. Domainko, S. Schindler, E. van Kampen, S. Kimeswenger, M. Ruffert, M. Mair et D. Breitschwerdt. « Metal Enrichment Processes in the ICM – Starbursts and Galactic Winds ». Proceedings of the International Astronomical Union 2, S235 (août 2006) : 212. http://dx.doi.org/10.1017/s1743921306006181.

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AbstractWe present an investigation of the metal enrichment of the intra-cluster medium (ICM) by galactic winds and merger-driven starbursts. We use combined N-body/hydrodynamic simulations with a semi-numerical galaxy formation model. The inhomogeneities in the metal distribution caused by these processes are an ideal tool to reveal the dynamical state of a galaxy cluster. We show that X-ray weighted metal maps distinguish between pre- or post-merger galaxy clusters by comparing the metallicity distribution with the galaxy-density distribution: pre-mergers have a metallicity gap between the subclusters, post-mergers a high metallicity between subclusters.
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42

Longobardi, A., A. Boselli, S. Boissier, S. Bianchi, P. Andreani, E. Sarpa, A. Nanni et M. Miville-Deschênes. « The GALEX Ultraviolet Virgo Cluster Survey (GUViCS) ». Astronomy & ; Astrophysics 633 (janvier 2020) : L7. http://dx.doi.org/10.1051/0004-6361/201937024.

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Aims. We present the first detection of diffuse dust in the intra-cluster medium of the Virgo cluster out to ∼0.4 virial radii, and study the radial variation of its properties on a radial scale of the virial radius. Methods. Analysing near-UV – i colours for a sample of ∼12 000 background galaxies with redshifts 0.02 < z < 0.8, we find significant colour reddening and relate it to variation in E(B − V) values. Results. The E(B − V) mean profile shows a dust component characterised by an average reddening E(B − V) ∼ 0.042 ± 0.004 mag within 1.5 degrees (∼0.3 rvir) from the cluster centre. Assuming a Large Magellanic Cloud extinction law, we derive an average visual extinction AV = 0.14 ± 0.01 for a total dust mass, Md = 2.5 ± 0.2 × 109 M⊙, hence a dust-to-gas mass ratio Md/Mg = 3.0 ± 0.3 × 10−4. Based on the upper limits on the flux density I250μm = 0.1 MJy sr−1 derived from Herschel data, we estimate an upper limit for the dust temperature of Td ∼ 10 K. However, similar densities can be obtained with dust at higher temperatures with lower emissivities. Conclusions. The Virgo cluster has diffuse dust in its intra-cluster medium characterised by different physical properties as those characterising the Milky Way dust. The diffuse dust in Virgo is transported into the cluster space through similar phenomena (stripping) as those building up the optical intra-cluster light, and it constitutes an additional cooling agent of the cluster gas.
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Lovisari, Lorenzo, Tatiana F. Laganá, Katharina Borm, Gerrit Schellenberger et Thomas H. Reiprich. « METALS IN THE ICM : WITNESSES OF CLUSTER FORMATION AND EVOLUTION ». Acta Polytechnica 53, A (18 décembre 2013) : 579–82. http://dx.doi.org/10.14311/ap.2013.53.0579.

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The baryonic composition of galaxy clusters and groups is dominated by a hot, X-ray emitting Intra-Cluster Medium (ICM). The mean metallicity of the ICM has been found to be roughly 0.3 ÷ 0.5 times the solar value, therefore a large fraction of this gas cannot be of purely primordial origin. Indeed, the distribution and amount of metals in the ICM is a direct consequence of the past history of star formation in the cluster galaxies and of the processes responsible for the injection of enriched material into the ICM. We here shortly summarize the current views on the chemical enrichment, focusing on the observational evidence in terms of metallicity measurements in clusters, spatial metallicity distribution and evolution, and expectations from future missions.
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Clavico, S., S. De Grandi, S. Ghizzardi, M. Rossetti, S. Molendi, F. Gastaldello, M. Girardi et al. « Growth and disruption in the Lyra complex ». Astronomy & ; Astrophysics 632 (22 novembre 2019) : A27. http://dx.doi.org/10.1051/0004-6361/201936467.

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Context. Nearby clusters of galaxies, z ≲ 0.1, are cosmic structures still under formation. Understanding the thermodynamic properties of merging clusters can provide crucial information on how they grow in the local universe. Aims. A detailed study of the intra-cluster medium (ICM) properties of un-relaxed systems is essential to understand the fate of in-falling structures and, more generally, the virialization process. Methods. We analyzed a mosaic of XMM-Newton observations (240 ks) of the Lyra system (z ∼ 0.067) that shows a complex dynamical state. Results. We find the main cluster RXC J1825.3+3026 to be in a late merger phase, whereas its companion CIZA J1824.1+3029 is a relaxed cool-core cluster. We estimate a mass ratio of ∼1 : 2 for the pair. No diffuse X-ray emission is found in the region between them, indicating that these clusters are in a pre-merger phase. We found evidence of a galaxy group infalling on RXC J1825.3+3026 in an advanced state of disruption. The SG, one of the brightest galaxies in the Lyra complex, was very likely at the center of the infalling group. This galaxy has a gaseous “corona” indicating that it was able to retain some of its gas after the ram-pressure stripping of the intra-group medium. In this scenario the diffuse emission excess observed southwest of RXC J1825.3+3026 could be due to gas once belonging to the group and/or to cluster ICM dislocated by the passage of the group. Finally, we identified three high-velocity galaxies aligned between RXC J1825.3+3026 and the SG, two of these showing evidence of gas stripped from them during infall. We estimate them to be currently falling onto the main cluster at an infall velocity of ∼3000 km s−1. Conclusions. Our study of the Lyra complex provides important clues about the processes presiding over the virialization of massive clusters in the local Universe.
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Mernier, F., J. de Plaa, J. S. Kaastra, Y. Y. Zhang, H. Akamatsu, L. Gu, P. Kosec et al. « Radial metal abundance profiles in the intra-cluster medium of cool-core galaxy clusters, groups, and ellipticals ». Astronomy & ; Astrophysics 603 (juillet 2017) : A80. http://dx.doi.org/10.1051/0004-6361/201630075.

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Kapferer, W., T. Kronberger, J. Weratschnig, S. Schindler, W. Domainko, E. van Kampen, S. Kimeswenger, M. Mair et M. Ruffert. « Metal enrichment of the intra-cluster medium over a Hubble time for merging and relaxed galaxy clusters ». Astronomy & ; Astrophysics 466, no 3 (24 avril 2007) : 813–21. http://dx.doi.org/10.1051/0004-6361:20066804.

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Bonafede, A., F. Govoni, L. Feretti, M. Murgia, G. Giovannini et M. Brüggen. « Fractional polarization as a probe of magnetic fields in the intra-cluster medium ». Astronomy & ; Astrophysics 530 (2 mai 2011) : A24. http://dx.doi.org/10.1051/0004-6361/201016298.

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Vazza, F., D. Eckert, A. Simionescu, M. Brüggen et S. Ettori. « Properties of gas clumps and gas clumping factor in the intra-cluster medium ». Monthly Notices of the Royal Astronomical Society 429, no 1 (5 décembre 2012) : 799–814. http://dx.doi.org/10.1093/mnras/sts375.

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Brunetti, Gianfranco. « The challenge of turbulent acceleration of relativistic particles in the intra-cluster medium ». Plasma Physics and Controlled Fusion 58, no 1 (20 octobre 2015) : 014011. http://dx.doi.org/10.1088/0741-3335/58/1/014011.

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Edwards, Louise O. V., et Dario Fadda. « Abell 1763 and its Cluster Feeding Filament : Constraints on the Intra-filament Medium ». Proceedings of the International Astronomical Union 6, S277 (décembre 2010) : 309–12. http://dx.doi.org/10.1017/s1743921311023003.

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AbstractGalaxies are found to inhabit a variety of environments. They are often found in pairs, groups, or clusters. Cosmological simulations predict that these clusters are connected on a larger scale by filaments, but because these large scale structures are so vast, and because they are of intermediate density, observational constraints on their properties are difficult to achieve. We find a large-scale filament in the Abell 1763-Abell 1770 superstructure, determine that the star-formation therein is enhanced, and uncover a bent double lobe radio source midway across the filament. From the bend of this AGN'a jets, we probe the density of the surrounding intra-filament medium (IFM), constrained to be between 1-20x10−29 gm/cm3. This density is consistent with direct probes of the IFM as well as theoretical models.
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