Annual Bibliography of English Language and Literature (Total 5598493 Papers Found)

The correlation function of galaxy clusters has frequently been used as a test of cosmological models. A number of assumptions are implicit in the comparison of theoretical expectations to data. Here we use an ensemble of ten large N-body simulations of the standard cold dark matter cosmology to investigate how cluster selection criteria and other uncertain factors influence the cluster correlation function. Our study is restricted to the idealized case where clusters are identified in the three ...
Properties of dark matter haloes can be probed observationally and numerically, and comparing both approaches provides ways to constrain cosmological models. When it comes to the inner part of galaxy cluster scale haloes, interaction between the baryonic and the dark matter component is an important issue that is far from being fully understood. With this work, we aim to initiate a program coupling observational and numerical studies to probe the inner part of galaxy clusters. In this article, w ...
ROSAT/HRI observations of the powerful radio-loud galaxy 3C382 reveal extended X-ray emission associated with the source. On the basis of this new spatial component, a previous ROSAT/PSPC spectral analysis of the source is revised. Allowing for the presence of an additional thermal component in the PSPC spectrum, the non-thermal component is found to be compatible with the extrapolation of the well defined 3C 382 —2 10 keV— power-law spectrum into the soft X-rays. The thermal –extended– ...
We use a redshift sample of Abell–ACO R ≥ 0 clusters with 401 measured and 16 estimated redshifts to derive the 2-point correlation function and the power spectrum of their redshift–space distribution. We find that the average value of the 2-point function within a sphere of radius R = 30 hMpc is 〈ξ(R) 〉 = 0.85 ± 0.15. Over the scale range 10 <∼ R <∼ 40 h Mpc, the power law 〈ξ(R) 〉 ∝ R is a good approximation. The power spectrum is reliably estimated for 0.03 <∼ ...
The image distortions of high-redshift galaxies caused by gravitational light deflection of foreground clusters of galaxies can be used to reconstruct the two-dimensional surface mass density of these clusters. We apply an unbiased parameter-free reconstruction technique to the cluster CL0939+4713 (Abell 851), observed with the WFPC2 on board of the HST. We demonstrate that a single deep WFPC2 observation can be used for cluster mass reconstruction despite its small field of view and the irregul ...
Extensive surveys of galaxy clusters motivate us to assess the likelihood of cluster–cluster lensing (CCL), namely, gravitational lensing of a background cluster by a foreground cluster. We briefly describe the characteristics of CCLs in optical, X-ray and Sunyaev–Zel’dovich effect measurements, and calculate their predicted numbers for cold dark matter ( CDM) parameters and a viable range of cluster mass functions and their uncertainties. The predicted number of CCLs in the strong-lensing ...
We present an analysis of the 2–point correlation function, ξ(r), of theX–ray Brightest Abell–type Cluster sample (XBACs; Ebeling et al. 1996) and of the cosmological constraints that it provides. If ξ(r) is modelled as a power–law, ξ(r) = (r0/r) γ , we find r0 ≃ 26.0 ± 4.5 h Mpc and γ ≃ 2.0 ± 0.4, with errors corresponding to 2σ uncertainties for one significant fitting parameter. As a general feature, ξ(r) is found to remain positive up to r ≃ 50–55 hMpc , after which ...
We consider a complex scalar field as SIMP dark matter in models with gauged Z3 discrete symmetry appearing as a remnant of dark local U(1). Dark matter (DM) annihilates dominantly by the 3-to-2 scattering, due to the DM cubic coupling in combination with the DM quartic coupling or the Z ′ gauge and dark Higgs couplings. We show that a light Z ′ gauge boson makes DM in kinetic equilibrium with thermal plasma at freezeout and it affects the DM relic density and perturbativity/unitarity constr ...
We report the results of hard X-ray observations of Abell 496 (A496), a nearby relaxed cluster, using the Rossi X-ray Timing Explorer (RXTE). The 3-20 keV spectrum of this cluster is well-modeled by a thermal component of kT ∼ 4.1 keV plus a cooling flow with mass accretion rate of Ṁ ∼ 285 M yr−1. The spectrum is equally well-modeled by a multi-temperature plasma component with a Gaussian temperature distribution of mean temperature 3.8 keV and σkT ∼ 0.9 keV. The metallicity is found ...
The theory predicts that the effect of gravitational lensing by the matter associated with clusters of galaxies can magnify background sources, leading to an enhancement of source number density around foreground clusters of galaxies. We conduct a search for the associations of distant radio-bright quasars with Abell clusters using the 1-Jy and 2-Jy all-sky catalogs. Statistics turns to be very poor on the basis of the 1-Jy sample, which shows no correlations between the distant radio quasars wi ...
In a much-noticed recent study Lauer and Postman (1994) found that the inertial frame defined by a sample of 119 nearby Abell clusters with cz⊙ < 15000 km s −1 showed a highly significant motion with respect to the cosmic microwave background (CMB) frame. We construct a subsample of their sample which comprises 64 Abell/ACO clusters with X-ray luminosities from ROSAT and brightest cluster galaxy (BCG) photometry from Lauer and Postman. We find that both BCG metric luminosities and residua ...
The purpose of the study was to investigate the relationship between aspects of children’s human figure drawings to their executive functioning and academic achievement. Participants consisted of 80 third and fourth graders, ages 8 to 10 years, along with their parents. Correlational analysis showed no relationship between the developmental scoring of the Goodenough-Harris or Koppitz with measures of executive functioning, as measured by the Behavior Rating Inventory of Executive Functioning ( ...
We apply a new non-parametric technique to reconstruct, with uncertainties, the projected mass distribution of the inner region of Abell 2218, using combined strong and weak lensing constraints from multiple-image systems and arclets with known redshifts. The reconstructed mass map broadly resembles previous, less detailed, parametric models, but when examined in detail shows several sub-structures, not necessarily associated with light but strongly required by the lensing data. In particular, t ...
We describe the properties of a remarkable group of actively star-forming dwarf galaxies and H II galaxies in the Abell 1367 cluster, which were discovered in a large-scale Hα imaging survey of the cluster. Approximately 30 Hα-emitting Visiting Astronomer, Kitt Peak National Observatory. KPNO is operated by AURA, Inc. under contract to the National Science Foundation. Part of the observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and ...
We present a determination of the Hubble constant, H0, from measurements of the Sunyaev-Zeldovich effect in an orientation-unbiased sample of seven galaxy clusters. With improved X-ray models and a more z ! 0.1 accurate 32 GHz calibration, we obtain km s 1 Mpc 1 for a standard cold dark matter (CDM) 14 H p 64 14 0 11 sys cosmology, or km s 1 Mpc 1 for a flat LCDM cosmology. In combination with X-ray cluster 14 H p 66 15 0 11 sys measurements and the big bang nucleosynthesis value for , we find . ...
We present a detailed X-ray study of the intracluster medium (ICM) of the nearby cool-core galaxy cluster Abell 478 (z 1⁄4 0:088), based on Chandra and XMM-Newton observations. Using a wavelet-smoothing hardness analysis, we derive detailed temperature maps of A478, revealing a surprising amount of temperature structure for an apparently well-relaxed cluster. We find the broadband Chandra spectral fits yield temperatures that are significantly hotter than those obtained with XMM-Newton, but th ...
Context. The study of galaxy luminosity functions (LFs) in different environments provides powerful constraints on the physics of galaxy evolution. The infrared (IR) LF is a particularly useful tool since it is directly related to the distribution of galaxy star-formation rates (SFRs). Aims. We aim to determine the galaxy IR LF as a function of the environment in a supercluster at redshift 0.23 to shed light on the processes driving galaxy evolution in and around clusters. Methods. We base our a ...
We present a detailed spatial and dynamical analysis of the central ∼ 2.2 h75 −1 Mpc region of the galaxy cluster Abell 521 (z=0.247), based on 238 spectra (of which 191 new measurements) obtained at the 3.6 m Telescope of the European Southern Observatory and at the Canada-France-Hawaii Telescope. From the analysis of the 125 galaxies that are confirmed members of the cluster, we derive a location (" mean " velocity) of CBI = 74019 +112 −125 km/s and detect a complex velocity distribution ...
I propose to generate an objective catalog of galaxy clusters in the northern sky, utilizing the Digitized Second Palomar Sky Survey (DPOSS). This thesis will consist of several related projects, namely: 1. Generation of a catalog of cluster candidates from DPOSS in two limited areas at high Galactic latitude. This will be performed using the object catalogs generated by SKICAT. 2. COSMIC spectroscopy of dense, centrally concentrated cluster candidates in four elds, to determine whether they are ...
Giant radio relics are arc-shaped diffuse sources with Mpc-scale found in the peripheries of some dynamically disturbed galaxy clusters. According to the leading scenario of relic formation, shock waves occurring in merger events amplify the local magnetic field and (re)accelerate particles. However, Mach numbers associated with merger shocks are typically low, and hence inefficient at accelerating particles from the thermal pool. We analyzed a deep Chandra observation (334 ks) to study the reli ...
In what follows I will compare Abell and Braselton's book with three other possible textbooks for a differential equations course: Birkhoff and Rota's Ordinary Differential Equations, Boyce and DiPrima's Elementary Differential Equations and Boundary-Value Problems, and Hubbard and West's Differential Equations, a dynamical systems approach, which is my current favourite and a radical departure from standard texts. ...
We study the distribution of galaxies and galaxy clusters in a 10 × 6 field in the Aquarius region. In addition to 63 clusters in the literature, we have found 39 new candidate clusters using a matched-filter technique and a counts-in-cells analysis. From redshift measurements of galaxies in the direction of these cluster candidates, we present new mean redshifts for 31 previously unobserved clusters, while improved mean redshifts are presented for 35 other systems. About 45% of the projected d ...
We investigate the properties of clusters of galaxies in the ΛCDM models with a steplike initial power spectrum. We examine the mass function, the peculiar velocities and the power spectrum of clusters in models with different values of the density parameter Ω0, the normalized Hubble constant h and the spectral parameter p, which describes the shape of the initial power spectrum. The results are compared with observations. We also investigate the rms bulk velocity in the models, where the prop ...
We present results from a 38 ks Chandra X–ray observation of the z = 0.059 galaxy cluster A1991. The cluster has a bright X-ray core and a central temperature gradient that declines inward from 2.7 keV at 130 kpc to ≈ 1.6 keV at the cluster center. The radiative cooling time of the gas in the inner 10 kpc is about 0.5 Gyr, and rises to 1 Gyr at a radius of 20 kpc. The cooling rate of the gas within the latter radius is <∼ 25 M⊙ yr −1 . The Chandra ACIS-S3 image shows that the intrac ...
We analyze the mass content of the massive strong-lensing cluster Abell 586 (z = 0.17). We use optical data (imaging and spectroscopy) obtained with the Gemini Multi-Object Spectrograph (GMOS) mounted on the 8-m Gemini-North telescope, together with publicly available X-ray data taken with the Chandra space telescope. Employing different techniques – velocity distribution of galaxies, weak gravitational lensing, and X-ray spatially resolved spectroscopy – we derive mass and velocity dispersi ...
We investigate a non-equilibrium ionization state and two-temperature structure of the intracluster medium in the linked region of Abell 399/401, using a series of N-body + SPH simulations, and find that there exist significant shock layers at the edge of the linked region, and that the ionization state of iron departs from the ionization equilibrium state at the shock layers and around the center of the linked region. As for the two-temperature structure, an obvious difference of temperature be ...
We present new Chandra observations of Abell 2199 that show evidence of gas sloshing due to a minor merger, as well as impacts of the radio source, 3C 338, hosted by the central galaxy, NGC 6166, on the intracluster gas. The new data are consistent with previous evidence of a Mach ≃ 1.46 shock 100 from the cluster center, although there is still no convincing evidence for the expected temperature jump. Other interpretations of this feature are possible, but none is fully satisfactory. Large sc ...
CLCWeb: Comparative Literature and Culture, the peer-reviewed, full-text, and open-access learned journal in the humanities and social sciences, publishes new scholarship following tenets of the discipline of comparative literature and the field of cultural studies designated as "comparative cultural studies." Publications in the journal are indexed in the Annual Bibliography of English Language and Literature (Chadwyck-Healey), the Arts and Humanities Citation Index (Thomson Reuters ISI), the H ...
We present the results of a spatially-resolved spectroscopic analysis of the galaxy cluster Abell 496 with the S3 chip on-board the Chandra satellite. We confirm the presence of a central positive temperature gradient consistent with a cooling flow, but with a minimum gas temperature of ∼0.5–0.9 keV. The cluster also exhibits sharp edges in gas density and temperature which are consistent with “cold front” substructures. The iron abundance profile is not radially symmetric relative to th ...
We present preliminary results of a simple peak finding algorithm applied to catalogues of galaxies, extracted from the Second Palomar Sky Survey in the framework of the CRoNaRio project. All previously known Abell and Zwicky clusters in a test region of 5 × 5 are recovered and new candidate clusters are also detected. This algorithm represents an alternative way of searching for galaxy clusters with respect to that implemented and tested at Caltech on the same type of data (Gal et al. 1998). ...
The steep mass profile of A1689 derived from recent detailed lensing observations is not readily reconciled with the low concentration halos predicted by the standard cold dark matter (CDM) model. However, halo triaxiality may act to bias the profile constraints derived assuming a spherically symmetric mass distribution, since lensing relates only to the projected mass distribution. A degree of halo triaxiality is inherent to the CDM structure formation, arising from the collision-less nature of ...
We have developed a parameter{independent method to detect local maxima of the two{point correlation function. By applying it to two samples of rich Abell clusters of galaxies with redshift limits z < 0:08 and z < 0:12 we detect three maxima centered at 150 h 1 Mpc, 300 h 1 Mpc and 430 h 1 Mpc with conndence levels 80% and higher. This sequence of uctuations has an average interval of 140 h 1 Mpc, that can be explained by a power spectrum with a distinct peak at k = 0:048 0:005 h Mpc 1 . ...
Although speculations of an interaction between galaxies and the ICM date back more than thirty years, the impact and importance of a possible interaction have long remained elusive. In recent years the situation has completely changed. A wealth of data and detailed hydrodynamical simulations have appeared that show the effects of interactions. Single dish observations show that cluster galaxies are deficient in their neutral hydrogen content out to two Abell radii. The deficient galaxies tend t ...
We present extended simulations of the large{scale distribution of galaxy clusters in several diierent dark matter models, using an optimized version of the Zel'dovich approximation. The high accuracy and low computational cost of this technique allow us to run a large ensemble of fty realizations for each model, and we are therefore able to make an accurate determination of the cosmic variance. Six diierent dark matter models are studied in this work: Standard CDM, Open CDM ((= 0:2), Tilted CDM ...
We present R OSAT PSPC and HRI observations of the distant cluster A1300 z = 0 : 3071 in conjunction with optical data, to investigate the physics of the intra-cluster medium and the dynamical state of the cluster. By means of a multi-resolution wavelet analysis, we nd evidence for structures in the X-ray emission of this very luminous L X 1:710 45 erg s ,1 in the 0.112.4 keV band and massive M tot 1:310 15 M at a radius 2.2 Mpc cluster. This cluster is signiicant a s w e appear to be witnessing ...
We have measured the flux, profile, color, and substructure in the diffuse intracluster light (ICL) in a sample of ten galaxy clusters with a range of mass, morphology, redshift, and density. Deep, widefield observations for this project were made in two bands at the one meter Swope and 2.5 meter du Pont telescope at Las Campanas Observatory. Careful attention in reduction and analysis was paid to the illumination correction, background subtraction, point spread function determination, and galax ...
We report an analysis of the dynamical structure of clusters of galaxies from a survey of photometric and spectroscopic observations in the fields of southern Abell Clusters. We analyze the galaxy velocity field in extended regions up to 7h Mpc from cluster centers and we estimate mean velocity dispersions and their radial dependence. Only one from a total number of 41 Abell clusters does not correspond to a dynamically bound system. However, four of these bound objects are double clusters. We e ...
We investigate the evolution of early-type galaxies in four clusters at z = 0.4 (Abell 370, Cl 0303+17, Cl 0939+47 and Cl 1447+26) and in one at z = 0.55 (Cl 0016+16). The galaxies are selected according to their spectrophotometrically determined spectral types and comprise the morphological classes E, S0 and Sa galaxies. Structural parameters are determined by a two-component fitting of the surface brightness profiles derived from HST images. Exploring a realistic range of K-corrections using B ...
We have observed with XMM-Newton the extended 4 Mpc filament detected by the ROSAT PSPC in the neighbourhood of the cluster of galaxies Abell 85. We confirm that there is an extended feature, aligned at the same position angle as the major axis of the central cD, the bright cluster galaxies, and nearby groups and clusters. We find that the X-ray emission from the filament is best described by thermal emission with a temperature of ∼ 2 keV, which is significantly lower than the ambient cluster ...
We report the first identification of a compact dense galaxy overdensity at z ∼ 8 dubbed A2744z8OD. A2744z8OD consists of eight Y -dropout galaxies behind Abell 2744 that is originally pinpointed by Hubble Frontier Fields studies. However, no studies have, so far, derived basic physical quantities of structure formation or made comparisons with theoretical models. We obtain a homogeneous sample of dropout galaxies at z ∼ 8 from eight field data of Hubble legacy images that are as deep as the ...
We analyze the density profiles and virial radii for a sample of 90 nearby clusters, using galaxies with available redshifts and positions. Each cluster has at least 20 redshifts measured within an Abell radius, and all the results come from galaxy sets of at least 20 members. Most of the density profiles of our clusters are well fitted by hydrostatic-isothermal-like profiles. The slopes we find for many cluster density profiles are consistent with the hypothesis that the galaxies are in equilib ...
I review the multiphase cooling flow equations that reduce to a relatively simple form for a wide class of self-similar density distributions described by a single parameter, k. It is shown that steady-state cooling flows are not consistent with all possible emissivity profiles which can therefore be used as a test of the theory. In combination, they provide strong constraints on the temperature profile and mass distribution within the cooling radius. The model is applied to ROSAT HRI data for 3 ...
We present results from the XMM-Newton observation of the non-cooling flow cluster A 1060. Large effective area of XMM-Newton enables us to investigate the nature of this cluster in unprecedented detail. From the observed surface brightness distribution, we have found that the gravitational mass distribution is well described by the NFW profile but with a central density slope of ∼1.5. We have undoubtedly detected a radial temperature decrease of as large as ∼30% from the center to the outer ...
CLCWeb: Comparative Literature and Culture, the peer-reviewed, full-text, and open-access learned journal in the humanities and social sciences, publishes new scholarship following tenets of the discipline of comparative literature and the field of cultural studies designated as "comparative cultural studies." Publications in the journal are indexed in the Annual Bibliography of English Language and Literature (Chadwyck-Healey), the Arts and Humanities Citation Index (Thomson Reuters ISI), the H ...
Semi-analytic treatment of the power spectrum with the approximation of constant linear bias provides a way to compare cosmological models to a large amount of data, as Peacock & Dodds (1994, 1996; hereafter PD94 and PD96, respectively) have shown. By applying the appropriate corrections to the observational power spectrum it is possible to recover the underlying linear power spectrum for any given cosmological model. Using extensive N-body simulations we carefully test and calibrate all importa ...
The color-magnitude relation (CMR) of early-type galaxies in clusters provides a powerful tool for finding clusters and determining photometric redshifts for clusters using two-filter imaging data. We demonstrate the high accuracy of photometric redshifts attainable using the CMR by applying the technique to a sample of 45 Abell clusters with known redshifts. Furthermore, by using the red sequence of galaxies from the CMR, we have developed an extremely efficient technique for detecting clusters ...
The core region of the Shapley Supercluster is dominated by three rich Abell clusters and two poor clusters. Since these member clusters are expected to be evolving rapidly in comparison to nonmember clusters because of the high merging rate, it is important to study the member clusters for understanding of the cluster evolution. Since the spatial distributions of gas temperature and metal abundance in each member cluster provide us with information on the interactions and motions of member clus ...
We report a new determination of the faint end of the galaxy luminosity function in the nearby clusters Virgo and Abell 2199 using data from SDSS and the Hectospec multifiber spectrograph on the MMT. The luminosity function of A2199 is consistent with a single Schechter function to Mr = −15.6 + 5 log h70 with a faint-end slope of α = −1.13 ± 0.07 (statistical). The LF in Virgo extends to Mr ≈ −13.5 ≈ M ∗ + 8 and has a slope of α = −1.28 ± 0.06 (statistical). The red sequence of ...
A recent Chandra observation of the nearby galaxy cluster Abell 585 has led to the discovery of an extended X-ray jet associated with the high-redshift background quasar B3 0727+409, a luminous radio source at redshift z = 2.5. This is one of only few examples of high-redshift X-ray jets known to date. It has a clear extension of about 12′′, corresponding to a projected length of ∼ 100 kpc, with a possible hot spot located 35′′ from the quasar. The archival high resolution VLA maps sur ...