Effect of the Environment on the Fundamental Plane of Elliptical Galaxies

We present an analysis of interacting E/S0 galaxies location on the Fundamental Plane. Using the NEMO package, we performed N-body simulations of close encounters and mergers between two spherical galaxies. We followed how structural and dynamical parameters (central density, half-mass radius and velocity dispersion)of galaxies are changed during the encounter. We analysed the dependence of these changes on initial mass concentration and presence of dark halo. The results of our simulations are used to discuss the Fundamental Plane for interacting early-type galaxies.Comment: Poster presented at JENAM-2000 (Joint European and National Astronomical meeting - S02. Morphology and dynamics of stellar systems: star clusters, galactic arms and rings

Formation of ultra-compact dwarf galaxies: tests of the galaxy threshing scenario in Fornax

This paper investigates the possibility that UCD galaxies in the Fornax cluster are formed by the threshing of nucleated, early-type dwarf galaxies (hereafter dwarf galaxies). Similar to the results of Cote et al. (2006) for the Virgo cluster, we show that the Fornax Cluster observations are consistent with a single population in which all dwarfs are nucleated, with a ratio of nuclear to total magnitude that varies slowly with magnitude. Importantly, the magnitude distribution of the UCD population is similar to that of the dwarf nuclei in the Fornax cluster. The joint population of UCDs and the dwarfs from which they may originate is modelled and shown to be consistent with an NFW profile with a characteristic radius of 5 kpc. Furthermore, a steady-state dynamical model reproduces the known mass profile of Fornax. However, there are a number of peculiarities in the velocity dispersion data that remain unexplained. The simplest possible threshing model is tested, in which dwarf galaxies move on orbits in a static cluster potential and are threshed if they pass within a radius at which the tidal force from the cluster exceeds the internal gravity at the core of their dark matter halo. This fails to reproduce the observed fraction of UCDs at radii greater than 30 kpc from the core of Fornax.Comment: 18 pages, accepted for publication by MNRAS Changes in response to referee's comments: Amended Figure 6 to allow for missing UCDs at large radii Modified discussio

Searches for Ultra-Compact Dwarf Galaxies in Galaxy Groups

We present the results of a search for ultra-compact dwarf galaxies (UCDs) in six different galaxy groups: Dorado, NGC1400, NGC0681, NGC4038, NGC4697 and NGC5084. We searched in the apparent magnitude range 17.5 < b_j < 20.5 (except NGC5084: 19.2 < b_j < 21.0). We found 1 definite plus 2 possible UCD candidates in the Dorado group and 2 possible UCD candidates in the NGC1400 group. No UCDs were found in the other groups. We compared these results with predicted luminosities of UCDs in the groups according to the hypothesis that UCDs are globular clusters formed in galaxies. The theoretical predictions broadly agree with the observational results, but deeper surveys are needed to fully test the predictions.Comment: 8 pages, 2 figures, accepted for publication in MNRA

Hematological parameters of rheumatoid arthritis patients undergoing total hip replacement

Abstract. Background Patients with rheumatoid arthritis (RA) and baseline anemia may have an increased risk of complications after total hip replacement (THR). Inflammation in RA is the main factor manifesting anaemia, neutropenia, thrombocytosis and eosinophilia. The changes in blood components are important for the outcomes of major orthopaedic surgery. The purpose was to identify hematological parameters in RA patients undergoing THR and assess the effect on intraoperative blood loss. Material and methods Outcomes of 44 THR patients treated for grade III degenerative coxarthrosis (n = 21, OA group) and RA coxarthrosis (n = 23, RA group) in Ekaterinburg regional hospital № 1 between 2018 and 2019 were reviewed. The patients' age ranged from 41 to 70 years. Clinical, radiological, laboratory examinations, computed tomography and statistical analysis were used for the study. Cell counting was produced with the Sysmex XT-4000i automated hematology system. Statistical analysis was performed using the tools of Statistica software. Nonparametric Mann-Whitney test was used to compare cell counts between the groups. The Spearman Rank correlation was used to analyse the correlation between the the cell counts in the groups. For calculations, a significance level of р < 0.05 was adopted. Results There were no significant differences in the preoperative white blood cell (WBC), neutrophil, lymphocyte, monocyte, eosinophil counts between RA and OA groups. The RA group showed an evident decrease in red blood cell (RBC) count and haemoglobin level as compared to OA group. The RA group demonstrated the higher platelet count with mean platelet volume (MPV) being significantly lower than that in the OA group. WBC count, neutrophils, in particular, was shown to increase with lymphocyte, RBC, platelet count and hemoglobin, plateletcrit levels decreased at 24 hours postoperatively. There were no significant differences in WBC and RBC counts in the groups postoperatively. The differences in the MPV were leveled up in the groups with the platelet count being higher in the RA group as compared to the OA group. Conclusions Hematological parameters of RA patients who had undergone specific preoperative preparation were not shown to be associated with greater blood loss during hip replacement surgery. The leukocyte count leveled up in the preoperative and early postoperative periods can be indicative of the absence of a significant effect of RA on the postoperative inflammation

Structural properties of ultra-compact dwarf galaxies in the Fornax and Virgo Clusters

We present a detailed analysis of high-resolution two-band Hubble Space Telescope Advanced Camera for Surveys imaging of 21 ultra-compact dwarf (UCD) galaxies in the Virgo and Fornax Clusters. The aim of this work is to test two formation hypotheses for UCDs—whether they are bright globular clusters (GCs) or stripped ("threshed") early-type dwarf galaxies—by direct comparison of UCD structural parameters and colors with GCs and galaxy nuclei. We find that the UCD surface brightness profiles can be described by a range of models and that the luminous UCDs in particular cannot be described by standard King models with tidal cutoffs as they have extended outer halos. This is not expected from traditional King models of GCs, but is consistent with recent results for massive GCs. The total luminosities, colors, and sizes of the UCDs (their position in the color-magnitude and luminosity-size diagrams) are consistent with them being either luminous GCs or threshed nuclei of both early-type and late-type galaxies (not just early-type dwarfs). For the most luminous UCDs we estimate color gradients over a limited range of radius. These are systematically positive in the sense of getting redder outward: mean Δ(F606W – F814W) = 0.14 mag per 100 pc with rms = 0.06 mag per 100 pc. The positive gradients found in the bright UCDs are consistent with them being either bright GCs or threshed early-type dwarf galaxies (except VUCD3). In contrast to the above results we find a very significant (>99.9% significance) difference in the sizes of UCDs and early-type galaxy nuclei: the effective radii of UCDs are 2.2+0.2 –0.1 times larger than those of early-type galaxy nuclei at the same luminosity. This result suggests that an important test can be made of the threshing hypothesis by simulating the process and predicting what size increase is expected

Chemodynamics of Compact Stellar Systems in NGC 5128: How similar are Globular Clusters, Ultra-Compact Dwarfs, and Dwarf Galaxies?

Velocity dispersion measurements are presented for luminous GCs in NGC 5128 derived from high-res. UVES spectra. The measurements are made with the pPXF code that parametrically recovers line-of-sight velocity dispersions. Combining the measured velocity dispersions with surface photometry and structural parameter data from HST enables both dynamical masses and M/L ratios to be derived. The fundamental plane relations of these clusters are investigated in order to fill the apparent gap between the relations of Local Group GCs and more massive early-type galaxies. It is found that the properties of these massive stellar systems match those of nuclear clusters in dwarf elliptical galaxies and UCDs better than those of Local Group GCs, and that all objects share similarly old (>8 Gyr) ages, suggesting a possible link between the formation and evolution of dE,Ns, UCDs and massive GCs. We find a very steep correlation between dynamical (M/L) ratio and dynamical mass of the form (M/L)_dyn ~ M_dyn^(0.24+/-0.02) above M_dyn = 2x10^6 Msol. Formation scenarios are investigated with a chemical abundance analysis using absorption line strengths calibrated to the Lick/IDS index system. The results lend support to two scenarios contained within a single general formation scheme. Old, massive, super-solar [alpha/Fe] systems are formed on short (<100 Myr) timescales through the merging of single-collapse GCs which themselves are formed within single, giant molecular clouds. More intermediate- and old-aged (~3-10 Gyr), solar- to sub-solar [alpha/Fe] systems are formed on much longer (~Gyr) timescales through the stripping of dE,Ns in the 10^13-10^15 Msol potential wells of massive galaxies and galaxy clusters.Comment: 12 pages (ApJ style) with 11 figures and 7 tables, accepted for publication in Ap