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Journal articles on the topic 'Galaxy clusters/dynamics study'

Author: Grafiati

Published: 4 June 2021

Last updated: 2 February 2022

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1

Benavides, José A., Laura V. Sales, and Mario G. Abadi. "Accretion of galaxy groups into galaxy clusters." Monthly Notices of the Royal Astronomical Society 498, no. 3 (2020): 3852–62. http://dx.doi.org/10.1093/mnras/staa2636.

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ABSTRACT We study the role of group infall in the assembly and dynamics of galaxy clusters in ΛCDM. We select 10 clusters with virial mass M200 ∼ 1014 $\rm M_\odot$ from the cosmological hydrodynamical simulation Illustris and follow their galaxies with stellar mass M⋆ ≥ 1.5 × 108 $\rm M_\odot$. A median of ${\sim}38{{\ \rm per\ cent}}$ of surviving galaxies at z = 0 is accreted as part of groups and did not infall directly from the field, albeit with significant cluster-to-cluster scatter. The evolution of these galaxy associations is quick, with observational signatures of their common origi

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Valenti, E., L. Origlia, and R. M. Rich. "Globular clusters in the near–infrared." Proceedings of the International Astronomical Union 5, H15 (2009): 555–56. http://dx.doi.org/10.1017/s1743921310010719.

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The study of Globular Cluster (GC) stellar populations (SPs) addresses fundamental astrophysical questions ranging from stellar structure, evolution and dynamics, to Galaxy formation. Indeed, they represent: i) fossils from the remote and violent epoch of Galaxy formation, ii) test particles for studying Galaxy dynamics and stellar dynamical model, and iii) fiducial templates for studying integrated light from distant stellar systems. In particular, high resolution spectroscopy of GC SPs provides abundance patterns which are crucial for understanding the formation and chemical enrichment time–

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Savini, F., A. Bonafede, M. Brüggen, et al. "A LOFAR study of non-merging massive galaxy clusters." Astronomy & Astrophysics 622 (February 2019): A24. http://dx.doi.org/10.1051/0004-6361/201833882.

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Centrally located diffuse radio emission has been observed in both merging and non-merging galaxy clusters. Depending on their morphology and size, we distinguish between giant radio haloes, which occur predominantly in merging clusters, and mini haloes, which are found in non-merging, cool-core clusters. In recent years, cluster-scale radio emission has also been observed in clusters with no sign of major mergers, showing that our knowledge of the mechanisms that lead to particle acceleration in the intra-cluster medium (ICM) is still incomplete. Low-frequency sensitive observations are requi

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John, Reju Sam, Surajit Paul, Luigi Iapichino, Karl Mannheim, and Harish Kumar. "Manufacturing cosmic rays in the evolving dynamical states of galaxy clusters." Monthly Notices of the Royal Astronomical Society 488, no. 1 (2019): 1301–19. http://dx.doi.org/10.1093/mnras/stz1785.

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ABSTRACT Galaxy clusters are known to be reservoirs of cosmic rays (CRs), as inferred from theoretical calculations or detection of CR-derived observables. CR acceleration in clusters is mostly attributed to the dynamical activity that produces shocks. Shocks in clusters emerge out of merger or accretion, but which one is more effective in producing CRs? at which dynamical phase? and why? To this aim, we study the production or injection of CRs through shocks and its evolution in the galaxy clusters using cosmological simulations with the enzo code. Particle acceleration model considered here

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Roberts, Ian D., and Laura C. Parker. "‘Observing’ unrelaxed clusters in dark matter simulations." Monthly Notices of the Royal Astronomical Society 490, no. 1 (2019): 773–83. http://dx.doi.org/10.1093/mnras/stz2666.

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ABSTRACT We present a detailed study of relaxed and unrelaxed galaxy clusters in a large dark matter only simulation. Recent work has demonstrated clear differences between the galaxy populations in clusters that have Gaussian velocity distributions (relaxed) compared to those that do not (unrelaxed). To directly compare with observations, we identify unrelaxed clusters in the simulations using one-dimensional velocity distributions. We show that non-Gaussian clusters have had recent major mergers and enhanced rates of galaxy infall relative to systems with Gaussian velocity profiles. Furtherm

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Cuciti, V., R. Cassano, G. Brunetti, et al. "Radio halos in a mass-selected sample of 75 galaxy clusters." Astronomy & Astrophysics 647 (March 2021): A51. http://dx.doi.org/10.1051/0004-6361/202039208.

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Context. Many galaxy clusters host megaparsec-scale diffuse radio sources called radio halos. Their origin is tightly connected to the processes that lead to the formation of clusters themselves. In order to reveal this connection, statistical studies of the radio properties of clusters combined with their thermal properties are necessary. For this purpose, we selected a sample of galaxy clusters with M500 ≥ 6 × 1014 M⊙ and z = 0.08 − 0.33 from the Planck Sunyaev–Zel’dovich catalogue. In Paper I, we presented the radio and X-ray data analysis that we carried out on the clusters of this sample.

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Botteon, A., R. Cassano, D. Eckert, et al. "Particle acceleration in a nearby galaxy cluster pair: the role of cluster dynamics." Astronomy & Astrophysics 630 (September 24, 2019): A77. http://dx.doi.org/10.1051/0004-6361/201936022.

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Context. Diffuse radio emission associated with the intracluster medium (ICM) is observed in a number of merging galaxy clusters. It is currently believed that a fraction of the kinetic energy in mergers is channeled into nonthermal components, such as turbulence, cosmic rays, and magnetic fields, which may lead to the formation of giant synchrotron sources in the ICM. Aims. Studying merging galaxy clusters in different evolutionary phases is fundamental for understanding the origin of radio emission in the ICM. Methods. We observed the nearby galaxy cluster pair RXC J1825.3+3026 (z ∼ 0.065) a

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Einasto, Maret, Boris Deshev, Heidi Lietzen, et al. "Infalling groups and galaxy transformations in the cluster A2142." Astronomy & Astrophysics 610 (February 2018): A82. http://dx.doi.org/10.1051/0004-6361/201731600.

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Context. Superclusters of galaxies provide dynamical environments for the study of the formation and evolution of structures in the cosmic web from galaxies, to the richest galaxy clusters, and superclusters themselves. Aims. We study galaxy populations and search for possible merging substructures in the rich galaxy cluster A2142 in the collapsing core of the supercluster SCl A2142, which may give rise to radio and X-ray structures in the cluster, and affect galaxy properties of this cluster. Methods. We used normal mixture modelling to select substructure of the cluster A2142. We compared al

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Stasyszyn, F. A., and M. de los Rios. "Faraday rotation measure dependence on galaxy cluster dynamics." Monthly Notices of the Royal Astronomical Society 487, no. 4 (2019): 4768–74. http://dx.doi.org/10.1093/mnras/stz1450.

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ABSTRACT We study the magnetic fields in galaxy clusters through Faraday rotation measurements crossing systems in different dynamical states. We confirm that magnetic fields are present in those systems and analyse the difference between relaxed and unrelaxed samples with respect to the dispersion between their inherent Faraday rotation measurements (RM). We found an increase of this RM dispersion and a higher RM overlapping frequency for unrelaxed clusters. This fact suggests that a large-scale physical process is involved in the nature of unrelaxed systems and possible depolarization effect

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Peña, J. H., and R. Peniche. "Photometry of early type stars in open clusters (NGC 1444, NGC 1662, NGC 2129, NGC 2169 and NGC 7209)." Symposium - International Astronomical Union 162 (1994): 303–4. http://dx.doi.org/10.1017/s0074180900215143.

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This is part of a series which has the purpose of examining the nature of the stars belonging to open clusters. The aim of this series is, among others things, to study short period pulsating stars, mainly of the Delta Scuti type, by first establishing the membership of each star to the cluster, to determine the abundance of the Be and Ap phenomena and blue stragglers in open clusters for clusters of different ages and metalicities and, eventually, to study the chemical enrichment of the galaxy when age, dynamics and metalicity are known for a fair number of clusters.

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11

Hwang, Narae, and Myung Gyoon Lee. "Tracing star cluster formation in the interacting galaxy M51." Proceedings of the International Astronomical Union 5, S266 (2009): 423–26. http://dx.doi.org/10.1017/s1743921309991591.

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AbstractWe present a study of star clusters in the interacting galaxy M51 using a star cluster catalog that includes about 3600 star clusters with mF555W < 23 mag, compiled by Hwang & Lee (2008). Combined with mF336W-band imaging data taken with the Hubble Space Telescope (HST)'s WFPC2 camera, we have derived the ages and masses of star clusters in M51 using theoretical population synthesis models. The cluster age distribution displays multiple peaks that correspond to the epochs of dynamical encounters predicted by theoretical model studies and the cluster-formation rate appears to inc

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Gonzalez, Elizabeth Johana, Martín de los Rios, Gabriel A. Oio, et al. "Analysis of candidates for interacting galaxy clusters." Astronomy & Astrophysics 611 (March 2018): A78. http://dx.doi.org/10.1051/0004-6361/201732003.

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Context. Merging galaxy clusters allow for the study of different mass components, dark and baryonic, separately. Also, their occurrence enables to test the ΛCDM scenario, which can be used to put constraints on the self-interacting cross-section of the dark-matter particle.Aim. It is necessary to perform a homogeneous analysis of these systems. Hence, based on a recently presented sample of candidates for interacting galaxy clusters, we present the analysis of two of these cataloged systems.Methods. In this work, the first of a series devoted to characterizing galaxy clusters in merger proces

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Aguerri, J. A. L., M. Girardi, I. Agulli, A. Negri, C. Dalla Vecchia, and L. Domínguez Palmero. "Deep spectroscopy in nearby galaxy clusters – V. The Perseus cluster." Monthly Notices of the Royal Astronomical Society 494, no. 2 (2020): 1681–92. http://dx.doi.org/10.1093/mnras/staa800.

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ABSTRACT Dwarfs are the largest population of galaxies in number in the nearby Universe. Deep spectroscopic data are still missing to obtain a better understanding of their formation and evolution processes. This study shows the results obtained from a spectroscopic campaign in the Perseus cluster. We have obtained 963 new galaxy spectra. We have measured the recessional velocity of the galaxies by using a cross-correlation technique. These data have been used to obtain the cluster membership, the dynamics of the galaxies, and the spectroscopic luminosity function (LF) of the cluster. The clus

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Okamoto, T., S. Yachi, and A. Habe. "Galaxy Distribution in Clusters of Galaxies." Symposium - International Astronomical Union 183 (1999): 262. http://dx.doi.org/10.1017/s0074180900132796.

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Galaxy distribution in clusters maybe affected by dynamical evolution of clusters and merging process of their member galaxies. In oreder to studey the effect, we study formation and evolution of galaxies in clusters by using N-body simulation. To identify galaxy size dark halos, we use the adaptive friends-of-friends algorithm (van Kampen 1995) at several red-shifts. At the same time, we treat galaxy merging and dark matter accretion to the galaxies by using the simple merging model. In this model we assume that galaxies have the merging cross section proportional to and if they encounter in

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Andreon, S., A. Moretti, G. Trinchieri, and C. H. Ishwara-Chandra. "Why are some galaxy clusters underluminous?" Astronomy & Astrophysics 630 (September 24, 2019): A78. http://dx.doi.org/10.1051/0004-6361/201935702.

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Our knowledge of the variety of galaxy clusters has been increasing in the last few years thanks to our progress in understanding the severity of selection effects on samples. To understand the reason for the observed variety, we study CL2015, a cluster (log M500/M⊙ = 14.39) easily missed in X-ray selected observational samples. Its core-excised X-ray luminosity is low for its mass M500, well below the mean relation for an X-ray selected sample, but only ∼1.5σ below that derived for an X-ray unbiased sample. We derived thermodynamic profiles and hydrostatic masses with the acquired deep Swift

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Girardi, M., W. Boschin, S. De Grandi, et al. "The velocity field of the Lyra complex." Astronomy & Astrophysics 633 (January 2020): A108. http://dx.doi.org/10.1051/0004-6361/201936466.

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Context. The formation of cosmic structures culminates with the assembly of galaxy clusters, a process that is quite different from cluster to cluster. Aims. We present the study of the structure and dynamics of the Lyra complex, consisting of the two clusters RXC J1825.3+3026 and CIZA J1824.1+3029, which was very recently studied by using both X-ray and radio data. Methods. This is the first analysis based on the kinematics of member galaxies. New spectroscopic data for 285 galaxies were acquired at the Italian Telescopio Nazionale Galileo and were used in combination with PanSTARRS photometr

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Assmann, P., M. Fellhauer, and M. I. Wilkinson. "Star clusters as building blocks for dSph galaxy formation." Proceedings of the International Astronomical Union 5, S266 (2009): 353–56. http://dx.doi.org/10.1017/s174392130999127x.

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AbstractWe study numerically the formation of dSph galaxies. Intense starbursts, e.g., in gas-rich environments, typically produce a few to a few hundred young star clusters within a region of just a few hundred pc. The dynamical evolution of these star clusters may explain the formation of the luminous component of dwarf spheroidal (dSph) galaxies. Here, we perform a numerical experiment to show that the evolution of star cluster complexes in dark-matter haloes can explain the formation of the luminous components of dSph galaxies.

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Muzzio, Juan C. "Cluster Swapping." Symposium - International Astronomical Union 126 (1988): 297–309. http://dx.doi.org/10.1017/s0074180900042558.

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The investigation of globular cluster swapping in clusters of galaxies has resulted in some interesting theoretical findings and, at the same time, it offers a promising field for observers. Numerical simulations of galaxy clusters where the galaxies have swarms of test particles around them showed that, in addition to tidal stripping, tidal accretion plays an important role in the dynamical evolution of clusters of galaxies; it also turns out that, even in clusters where the gravitational field is dominated by a massive background, the galaxy-galaxy attraction cannot be ignored when estimatin

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Funato, Yoko. "Evolution of Galaxies in Clusters." Symposium - International Astronomical Union 208 (2003): 199–208. http://dx.doi.org/10.1017/s0074180900207158.

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In this paper I show recent results of our studies on the evolution of an isolated cluster of galaxies using N-body simulations. In Sensui, Funato & Makino (1999) only one initial cluster model are investigated. In the present study, we varied the initial model of galaxies and clusters, and studied the dependence of evolution on initial conditions. We found that the mass of galactic halos are stripped and a common halo develops for any cluster models. Using result of scattering experiments of two halo-halo encounters, we show that the growth rate of the common halo (and complimentarily dec

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Ramamani, Natarajan. "The Dynamics of Globular Cluster Systems." Symposium - International Astronomical Union 126 (1988): 641–42. http://dx.doi.org/10.1017/s0074180900043448.

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This paper describes a project whose aim is to study the dynamics of a globular cluster system using an N-body code modified to include the gravitational field of an isothermal galaxy model. The galaxy and the globular cluster system have the same radii, are spherically symmetric and non-rotating. The evolution is to be followed up to a Hubble time.

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Gnedin, Oleg Y., and José L. Prieto. "Dynamical Evolution of Globular Clusters in Hierarchical Cosmology." Proceedings of the International Astronomical Union 3, S246 (2007): 403–7. http://dx.doi.org/10.1017/s1743921308016049.

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AbstractWe probe the evolution of globular clusters that could form in giant molecular clouds within high-redshift galaxies. Numerical simulations demonstrate that the large and dense enough gas clouds assemble naturally in current hierarchical models of galaxy formation. These clouds are enriched with heavy elements from earlier stars and could produce star clusters in a similar way to nearby molecular clouds. The masses and sizes of the model clusters are in excellent agreement with the observations of young massive clusters. Do these model clusters evolve into globular clusters that we see

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Haggar, Roan, Meghan E. Gray, Frazer R. Pearce, et al. "TheThreeHundred project: backsplash galaxies in simulations of clusters." Monthly Notices of the Royal Astronomical Society 492, no. 4 (2020): 6074–85. http://dx.doi.org/10.1093/mnras/staa273.

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ABSTRACT In the outer regions of a galaxy cluster, galaxies either may be falling into the cluster for the first time or have already passed through the cluster centre at some point in their past. To investigate these two distinct populations, we utilize TheThreeHundred project, a suite of 324 hydrodynamical resimulations of galaxy clusters. In particular, we study the ‘backsplash population’ of galaxies: those that have passed within R200 of the cluster centre at some time in their history, but are now outside of this radius. We find that, on average, over half of all galaxies between R200 an

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Buta, R. "Star Clusters in Galactic Resonance Rings." Symposium - International Astronomical Union 207 (2002): 447–49. http://dx.doi.org/10.1017/s0074180900224169.

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Resonance rings are intriguing sites of organized star formation in some galaxies. The Hubble Space Telescope Wide Field and Planetary Camera 2 has been used to image several resonance rings at high resolution in order to study the star clusters in the rings. Here I summarize results on inner Lindblad resonance rings in ESO 565–11 and NGC 1326, and on an inner 4:1 resonance ring in the Seyfert 2 galaxy NGC 3081. The latter ring provides one of the strongest cases illustrating the connection between star formation and dynamics in disk galaxies.

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Fellhauer, Michael. "Building Dwarf Galaxies out of Merged Young Star Clusters." Symposium - International Astronomical Union 207 (2002): 730–32. http://dx.doi.org/10.1017/s0074180900224704.

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Young star clusters in interacting galaxies are often found in groups or clusters of star clusters containing up to 100 single clusters. In our project we study the future fate of these clusters of star clusters. We find that the star clusters merge on time scales of a few dynamical crossing times of the super-cluster. The resulting merger object has similarities with observed dwarf ellipticals (dE). Furthermore, if destructive processes like tidal heating, dynamical friction or interaction with disc or bulge of the parent galaxy are taken into account our merger objects may evolve into object

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Fan, Zhou, and Yanbin Yang. "Spectroscopic study of formation, evolution and interaction of M31 and M33 with star clusters." Proceedings of the International Astronomical Union 10, S312 (2014): 201–2. http://dx.doi.org/10.1017/s1743921315007814.

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AbstractThe recent studies show that the formation and evolution process of the nearby galaxies are still unclear. By using the Canada France Hawaii Telescope (CFHT) 3.6m telescope, the PanDAS shows complicated substructures (dwarf satellite galaxies, halo globular clusters, extended clusters, star streams, etc.) in the halo of M31 to ~150 kpc from the center of galaxy and M31-M33 interaction has been studied. In our work, we would like to investigate formation, evolution and interaction of M31 and M33, which are the nearest two spiral galaxies in Local Group. The star cluster systems of the t

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Huchra, J., E. Tollestrup, S. Schneider, et al. "The 2Mass Redshift Survey." Highlights of Astronomy 11, no. 1 (1998): 487–91. http://dx.doi.org/10.1017/s1539299600021833.

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With the current convergence of determinations of the Hubble Constant (e.g. The Extragalactic Distance Scale, 1997, Livio, Donahue and Panagia, eds.) to values within ±25% rather than a factor of two, and the clear possibility of determining q0 using high redshift supernovae (Garnavich et al. 1998), the major remaining problem in observational cosmology is the determination of Ω — what is the dark matter, how much is there, and how is it distributed?The most direct approach to the last two parts of the question has been to study galaxy dynamics, first through the motions of galaxies in binarie

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Sakurai, Yuya, Naoki Yoshida, and Michiko S. Fujii. "Growth of intermediate mass black holes in first star clusters." Proceedings of the International Astronomical Union 14, S351 (2019): 220–23. http://dx.doi.org/10.1017/s1743921319007245.

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AbstractWe study runaway stellar collisions in primordial star clusters and formation of intermediate mass black holes (IMBHs). Using cosmological simulations, we identify eight atomic-cooling halos in which the star clusters form. We follow stellar and dark matter (DM) dynamics for 3Myr using hybrid N-body simulations. We find that the runaway stellar collisions occur in all star clusters and IMBHs with masses ∼400–1900M⊙ form. Performing additional N-body simulations, we explore evolutions of the IMBHs in the star clusters for 15 Myr. The IMBH masses grow via stellar tidal disruption events

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Di Gennaro, G., T. Venturi, D. Dallacasa, et al. "Cosmic dance in the Shapley Concentration Core." Astronomy & Astrophysics 620 (November 23, 2018): A25. http://dx.doi.org/10.1051/0004-6361/201832801.

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Context. The Shapley Concentration (⟨z⟩ ≈ 0.048) covers several degrees in the southern hemisphere, and includes galaxy clusters in advanced evolutionary stages, groups of clusters in the very early stages of merger, fairly massive clusters with ongoing accretion activity, and smaller groups located in filaments in the regions between the main clusters. Aims. With the goal to investigate the role of cluster mergers and accretion on the radio galaxy population, we performed a multi-wavelength study of the brightest cluster galaxies (BCGs) and of the galaxies showing extended radio emission in t

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Gal, Roy, L. M. Lubin, and G. K. Squires. "The ORELSE Survey." Proceedings of the International Astronomical Union 2, S235 (2006): 165–66. http://dx.doi.org/10.1017/s1743921306005862.

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AbstractThe ORELSE Survey (Observations of Redshift Evolution in Large Scale Environments) is a multi-wavelength program to study the large-scale structure around a sample of 20z>0.6 clusters, with the goal of understanding transformative processes affecting galaxies in a broad range of environments. The survey includes (1) deep optical imaging to map structure around the clusters; (2) optical spectroscopy to confirm redshifts, map the galaxy distribution, obtain cluster masses via dynamical estimates, and measure spectral properties; (3) ground-based K-band imaging, to better constrain gal

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De Luca, Federico, Marco De Petris, Gustavo Yepes, Weiguang Cui, Alexander Knebe, and Elena Rasia. "The Three Hundred project: dynamical state of galaxy clusters and morphology from multiwavelength synthetic maps." Monthly Notices of the Royal Astronomical Society 504, no. 4 (2021): 5383–400. http://dx.doi.org/10.1093/mnras/stab1073.

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ABSTRACT We study the connection between morphology and dynamical state of the simulated galaxy clusters in z ∈ [0, 1.031] from The Three Hundred project. We quantify cluster dynamical state using a combination of dynamical indicators from theoretical measures and compare this combined parameter, χ, with the results from morphological classifications. The dynamical state of the cluster sample shows a continuous distribution from dynamically relaxed, more abundant at lower redshift, to hybrid and disturbed. The dynamical state presents a clear dependence on the radius, with internal regions mor

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Mandal, S., H. T. Intema, R. J. van Weeren, et al. "Revived fossil plasma sources in galaxy clusters." Astronomy & Astrophysics 634 (January 28, 2020): A4. http://dx.doi.org/10.1051/0004-6361/201936560.

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It is well established that particle acceleration by shocks and turbulence in the intra-cluster medium can produce cluster-scale synchrotron emitting sources. However, the detailed physics of these particle acceleration processes is still not well understood. One of the main open questions is the role of fossil relativistic electrons that have been deposited in the intracluster medium (ICM) by radio galaxies. These synchrotron-emitting electrons are very difficult to study as their radiative lifetime is only tens of Myr at gigahertz frequencies, and they are therefore a relatively unexplored p

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Dotti, F. Flammini, Maxwell Xu Cai, Rainer Spurzem, and M. B. N. Kouwenhoven. "Planetary Systems in Star Clusters: the dynamical evolution and survival." Proceedings of the International Astronomical Union 14, S345 (2018): 293–94. http://dx.doi.org/10.1017/s174392131900142x.

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AbstractMost stars form in crowded stellar environments. Such star forming regions typically dissolve within ten million years, while others remain bound as stellar groupings for hundreds of millions to billions of years, and then become the open clusters or globular clusters that are present in our Milky Way galaxy today. A large fraction of stars in the Galaxy hosts planetary companions. To understand the origin and dynamical evolution of such exoplanet systems, it is necessary to carefully study the effect of their environments. Here, we combine theoretical estimates with state-of-the-art n

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Hodson, Alistair O., Hongsheng Zhao, Justin Khoury, and Benoit Famaey. "Galaxy clusters in the context of superfluid dark matter." Astronomy & Astrophysics 607 (November 2017): A108. http://dx.doi.org/10.1051/0004-6361/201630069.

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Context. The mass discrepancy in the Universe has not been solved by the cold dark matter (CDM) or the modified Newtonian dynamics (MOND) paradigms so far. The problems and solutions of either scenario are mutually exclusive on large and small scales. It has recently been proposed, by assuming that dark matter is a superfluid, that MOND-like effects can be achieved on small scales whilst preserving the success of ΛCDM on large scales. Detailed models within this “superfluid dark matter” (SfDM) paradigm are yet to be constructed. Aims. Here, we aim to provide the first set of spherical models o

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Einasto, Maret, Rain Kipper, Peeter Tenjes, et al. "The Corona Borealis supercluster: connectivity, collapse, and evolution." Astronomy & Astrophysics 649 (May 2021): A51. http://dx.doi.org/10.1051/0004-6361/202040200.

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Context. Rich superclusters of galaxies represent dynamically active environments in which galaxies and their systems form and evolve. Aims. We study the dynamical properties and connectivity of the richest galaxy clusters in the Corona Borealis (CB) supercluster and of the whole supercluster, and analyse star formation of galaxies in them with the aim to understand the evolution of the supercluster and the galaxies within it. We compare it with the supercluster SCl A2142. Methods. We used the luminosity-density field to determine the high-density cores of the CB. We identified the richest gal

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Ruppin, F., F. Sembolini, M. De Petris, et al. "Impact of ICM disturbances on the mean pressure profile of galaxy clusters: A prospective study of the NIKA2 SZ large program with MUSIC synthetic clusters." Astronomy & Astrophysics 631 (October 15, 2019): A21. http://dx.doi.org/10.1051/0004-6361/201935059.

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Context. The mean pressure profile of the galaxy cluster population plays an essential role in cosmological analyses. An accurate characterization of the shape, intrinsic scatter, and redshift evolution of this profile is necessary to estimate some of the biases and systematic effects that currently prevent cosmological analyses based on thermal Sunyaev-Zel’dovich (tSZ) surveys from obtaining precise and unbiased cosmological constraints. This is one of the main goals of the ongoing NIKA2 SZ large program, which aims at mapping the tSZ signal of a representative cluster sample selected from th

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Botteon, A., S. Giacintucci, F. Gastaldello, et al. "Nonthermal phenomena in the center of Abell 1775." Astronomy & Astrophysics 649 (May 2021): A37. http://dx.doi.org/10.1051/0004-6361/202040083.

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Context. Thermal gas in the center of galaxy clusters can show substantial motions that generate surface-brightness and temperature discontinuities known as cold fronts. The motions may be triggered by minor or off-axis mergers that preserve the cool core of the system. The dynamics of the thermal gas can also generate radio emission from the intra-cluster medium (ICM) and impact the evolution of clusters’ radio sources. Aims. We aim to study the central region of Abell 1775, a system in an ambiguous dynamical state at z = 0.072 which is known to host an extended head-tail radio galaxy, with t

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Jeffery, Elizabeth J. "Observational problems in determining the ages of open clusters." Proceedings of the International Astronomical Union 4, S258 (2008): 141–52. http://dx.doi.org/10.1017/s1743921309031792.

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AbstractOpen clusters have long been objects of interest in astronomy. As a good approximation of essentially pure stellar populations, they have proved very useful for studies in a wide range of astrophysically interesting questions, including stellar evolution and atmospheres, the chemical and dynamical evolution of our Galaxy, and the structure of our Galaxy. Of fundamental importance to our understanding of open clusters is accurate determinations of cluster ages. Currently there are two main techniques for independently determining the ages of stellar populations: main sequence evolution

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Marini, I., A. Saro, S. Borgani, et al. "On the phase-space structure of galaxy clusters from cosmological simulations." Monthly Notices of the Royal Astronomical Society 500, no. 3 (2020): 3462–80. http://dx.doi.org/10.1093/mnras/staa3486.

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ABSTRACT Cosmological N-body simulations represent an excellent tool to study the formation and evolution of dark matter (DM) haloes and the mechanisms that have originated the universal profile at the largest mass scales in the Universe. In particular, the combination of the velocity dispersion σv with the density ρ can be used to define the pseudo-entropy $S(r)=\sigma _\mathrm{v}^2/\rho ^{\, 2/3}$, whose profile is well described by a simple power law $S\propto \, r^{\, \alpha }$. We analyse a set of cosmological hydrodynamical re-simulations of massive galaxy clusters and study the pseudo-e

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Boschin, W., M. Girardi, and F. Gastaldello. "A spectroscopic survey of Abell 1703: is it a rare relaxed cluster hosting a radio halo or a usual merging system?" Monthly Notices of the Royal Astronomical Society 492, no. 2 (2020): 2405–17. http://dx.doi.org/10.1093/mnras/staa015.

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ABSTRACT We present the study of the internal dynamics of the intriguing galaxy cluster Abell 1703, a system hosting a probable giant radio halo whose dynamical status is still controversial. Our analysis is based on unpublished spectroscopic data acquired at the Italian Telescopio Nazionale Galileo and data publicly available in the literature. We also use photometric data from the Sloan Digital Sky Survey. We select 147 cluster members and compute the cluster redshift 〈z〉 ∼ 0.277 and the global line-of-sight velocity dispersion σv ∼ 1300 km s−1. We infer that Abell 1703 is a massive cluster:

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Vazza, F., D. Wittor, G. Brunetti, and M. Brüggen. "Simulating the transport of relativistic electrons and magnetic fields injected by radio galaxies in the intracluster medium." Astronomy & Astrophysics 653 (September 2021): A23. http://dx.doi.org/10.1051/0004-6361/202140513.

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Radio galaxies play an important role in the seeding of cosmic rays and magnetic fields in galaxy clusters. Here, we simulate the evolution of relativistic electrons injected into the intracluster medium by radio galaxies. Using passive tracer particles added to magnetohydrodynamical adaptive-mesh simulations, we calculated the evolution of the spectrum of relativistic electrons, taking into account energy losses and re-acceleration mechanisms associated with the dynamics of the intracluster medium. Re-acceleration can occur at shocks via diffusive shock acceleration, and in turbulent flows vi

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Ramos-Almendares, Felipe, Laura V. Sales, Mario G. Abadi, Jessica E. Doppel, Hernan Muriel, and Eric W. Peng. "Simulating the spatial distribution and kinematics of globular clusters within galaxy clusters in illustris." Monthly Notices of the Royal Astronomical Society 493, no. 4 (2020): 5357–68. http://dx.doi.org/10.1093/mnras/staa551.

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ABSTRACT We study the assembly of globular clusters (GCs) in 9 galaxy clusters using the cosmological simulation Illustris. GCs are tagged to individual galaxies at their infall time. The tidal removal of GCs from their galaxies and the distribution of the GCs within the cluster is later followed self-consistently by the simulation. The method relies on the simple assumption of a single power-law relation between halo mass (Mvir) and mass in GCs (MGC) as found in observations. We find that the GCs specific frequency SN as a function of V-band magnitude naturally reproduces the observed ‘U’-sha

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Thölken, Sophia, Tim Schrabback, Thomas H. Reiprich, et al. "XMM-Newton X-ray and HST weak gravitational lensing study of the extremely X-ray luminous galaxy cluster Cl J120958.9+495352 (z = 0.902)." Astronomy & Astrophysics 610 (February 2018): A71. http://dx.doi.org/10.1051/0004-6361/201730913.

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Context. Observations of relaxed, massive, and distant clusters can provide important tests of standard cosmological models, for example by using the gas mass fraction. To perform this test, the dynamical state of the cluster and its gas properties have to be investigated. X-ray analyses provide one of the best opportunities to access this information and to determine important properties such as temperature profiles, gas mass, and the total X-ray hydrostatic mass. For the last of these, weak gravitational lensing analyses are complementary independent probes that are essential in order to tes

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Samurovic, S. "Dynamical models of two lenticular galaxies: NGC 1023 and NGC 4526." Serbian Astronomical Journal, no. 195 (2017): 9–21. http://dx.doi.org/10.2298/saj170330006s.

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We study kinematics and dynamics of two lenticular galaxies that possess globular clusters (GCs) which extend beyond approximately seven effective radii. We analyze two nearby lenticular galaxies, NGC 1023 and NGC 4526, based on their GCs. We extract the kinematics of these galaxies and use it for dynamical modeling based on the Jeans equation. The Jeans equation was solved in both the Newtonian mass-follows-light approach assuming constant mass-to-light ratio and assuming a dark halo in the Navarro-Frenk-White form. We find that while the first galaxy, NGC 1023, does not need a significant am

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Menacho, Veronica, and Miguel Verdugo. "Linking star formation and galaxy kinematics in the massive cluster Abell 2163." Proceedings of the International Astronomical Union 10, S309 (2014): 330. http://dx.doi.org/10.1017/s1743921314010242.

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AbstractThe origin of the morphology-density relation is still an open question in galaxy evolution. It is most likely driven by the combination of the efficient star formation in the highest peaks of the mass distribution at high-z and the transformation by environmental processes at later times as galaxies fall into more massive halos. To gain additional insights about these processes we study the kinematics, star formation and structural properties of galaxies in Abell 2163 a very massive (~4×1015 M⊙, Holz & Perlmutter 2012) merging cluster at z = 0.2.We use high resolution spectroscopy

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Hamilton, Chris, and Roman R. Rafikov. "Secular dynamics of binaries in stellar clusters – III. Doubly averaged dynamics in the presence of general-relativistic precession." Monthly Notices of the Royal Astronomical Society 505, no. 3 (2021): 4151–77. http://dx.doi.org/10.1093/mnras/stab1284.

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ABSTRACT Secular evolution of binaries driven by an external (tidal) potential is a classic astrophysical problem. Tidal perturbations can arise due to an external point mass, as in the Lidov–Kozai (LK) theory of hierarchical triples, or due to an extended stellar system (e.g. galaxy or globular cluster) in which the binary resides. For many applications, general-relativistic (GR) apsidal precession is important, and has been accounted for in some LK calculations. Here, we generalize and extend these studies by exploring in detail the effect of GR precession on (quadrupole-level) tidal evoluti

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Clavico, S., S. De Grandi, S. Ghizzardi, et al. "Growth and disruption in the Lyra complex." Astronomy & Astrophysics 632 (November 22, 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 J

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Knowles, K., D. S. Pillay, S. Amodeo, et al. "MERGHERS pilot: MeerKAT discovery of diffuse emission in nine massive Sunyaev–Zel’dovich-selected galaxy clusters from ACT." Monthly Notices of the Royal Astronomical Society 504, no. 2 (2021): 1749–58. http://dx.doi.org/10.1093/mnras/stab939.

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ABSTRACT The MeerKAT Exploration of Relics, Giant Halos, and Extragalactic Radio Sources (MERGHERS) survey is a planned project to study a large statistical sample of galaxy clusters with the MeerKAT observatory. Here we present the results of a 16-h pilot project, observed in response to the 2019 MeerKAT Shared Risk proposal call, to test the feasibility of using MeerKAT for a large cluster study using short (0.2–2.1 h) integration times. The pilot focuses on 1.28-GHz observations of 13 massive, low-to-intermediate redshift (0.22 &lt; z &lt; 0.65) clusters from the Sunyaev–Zel’dovich-

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Bastian, Nate, Mark Gieles, Barbara Ercolano, and Robert Gutermuth. "The spatial evolution of stellar structures in the LMC/SMC." Proceedings of the International Astronomical Union 4, S256 (2008): 45–50. http://dx.doi.org/10.1017/s174392130802824x.

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AbstractWe present an analysis of the spatial distribution of various stellar populations within the Large and Small Magellanic Clouds. We use optically selected stellar samples with mean ages between ~9 and ~1000 Myr, and existing stellar cluster catalogues to investigate how stellar structures form and evolve within the LMC/SMC. We use two statistical techniques to study the evolution of structure within these galaxies, the Q-parameter and the two-point correlation function (TPCF). In both galaxies we find the stars are born with a high degree of substructure (i.e. are highly fractal) and th

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Ferragamo, A., J. A. Rubiño-Martín, J. Betancort-Rijo, E. Munari, B. Sartoris, and R. Barrena. "Biases in galaxy cluster velocity dispersion and mass estimates in the small Ngal regime." Astronomy & Astrophysics 641 (September 2020): A41. http://dx.doi.org/10.1051/0004-6361/201834837.

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Aims. We present a study of the statistical properties of three velocity dispersion and mass estimators: biweight, gapper, and standard deviation for a small number of galaxies (Ngal ≤ 75). Methods. Using a set of 73 numerically simulated galaxy clusters, we first characterised the statistical bias and the variance for each one of the three estimators (biweight, gapper, and standard deviation) in the determination of the velocity dispersion and the dynamical mass of the clusters through the σ–M relation. These results were used to define a new set of unbiased estimators that are able to correc

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Gouliermis, Dimitrios A., and Sacha Hony. "NGC 346: Looking in the Cradle of a Massive Star Cluster." Proceedings of the International Astronomical Union 12, S316 (2015): 117–22. http://dx.doi.org/10.1017/s1743921316008759.

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AbstractHow does a star cluster of more than few 10,000 solar masses form? We present the case of the cluster NGC 346 in the Small Magellanic Cloud, still embedded in its natal star-forming region N66, and we propose a scenario for its formation, based on observations of the rich stellar populations in the region. Young massive clusters host a high fraction of early-type stars, indicating an extremely high star formation efficiency. The Milky Way galaxy hosts several young massive clusters that fill the gap between young low-mass open clusters and old massive globular clusters. Only a handful,

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