Stellar kinematics of X-ray bright massive elliptical galaxies

We discuss a simple and fast method for estimating masses of early-type galaxies from optical data and compare the results with X-ray derived masses. The optical method relies only on the most basic observables such as the surface brightness $I(R)$ and the line-of-sight velocity dispersion $\sigma_p(R)$ profiles and provides an anisotropy-independent estimate of the galaxy circular speed $V_c$. The mass-anisotropy degeneracy is effectively overcome by evaluating $V_c$ at a characteristic radius $R_{\rm sweet}$ defined from {\it local} properties of observed profiles. The sweet radius $R_{\rm sweet}$ is expected to lie close to $R_2$, where $I(R) \propto R^{-2}$, and not far from the effective radius $R_{\rm eff}$. We apply the method to a sample of five X-ray bright elliptical galaxies observed with the 6-m telescope BTA-6 in Russia. We then compare the optical $V_c$-estimate with the X-ray derived value, and discuss possible constraints on the non-thermal pressure in the hot gas and configuration of stellar orbits. We find that the average ratio of the optical $V_c$-estimate to the X-ray one is equal to $\approx 0.98$ with $11 \%$ scatter, i.e. there is no evidence for the large non-thermal pressure contribution in the gas at $\sim R_{\rm sweet}$. From analysis of the Lick indices H$\beta$, Mgb, Fe5270 and Fe5335, we calculate the mass of the stellar component within the sweet radius. We conclude that a typical dark matter fraction inside $R_{\rm sweet}$ in the sample galaxies is $\sim 60\%$ for the Salpeter IMF and $\sim 75 \%$ for the Kroupa IMF.Comment: accepted for publication in MNRA

A Uniform Contribution of Core-Collapse and Type Ia Supernovae to the Chemical Enrichment Pattern in the Outskirts of the Virgo Cluster

We present the first measurements of the abundances of $\alpha$-elements (Mg, Si, and S) extending out to beyond the virial radius of a cluster of galaxies. Our results, based on Suzaku Key Project observations of the Virgo Cluster, show that the chemical composition of the intra-cluster medium is consistent with being constant on large scales, with a flat distribution of the Si/Fe, S/Fe, and Mg/Fe ratios as a function of radius and azimuth out to 1.4 Mpc (1.3 $r_{200}$). Chemical enrichment of the intergalactic medium due solely to core collapse supernovae (SNcc) is excluded with very high significance; instead, the measured metal abundance ratios are generally consistent with the Solar value. The uniform metal abundance ratios observed today are likely the result of an early phase of enrichment and mixing, with both SNcc and type Ia supernovae (SNIa) contributing to the metal budget during the period of peak star formation activity at redshifts of 2-3. We estimate the ratio between the number of SNIa and the total number of supernovae enriching the intergalactic medium to be between 12-37%, broadly consistent with the metal abundance patterns in our own Galaxy or with the SNIa contribution estimated for the cluster cores.Comment: accepted for publication in ApJ

Quantifying properties of ICM inhomogeneities

We present a new method to identify and characterize the structure of the intracluster medium (ICM) in simulated galaxy clusters. The method uses the median of gas properties, such as density and pressure, which we show to be very robust to the presence of gas inhomogeneities. In particular, we show that the radial profiles of median gas properties are smooth and do not exhibit fluctuations at locations of massive clumps in contrast to mean and mode properties. It is shown that distribution of gas properties in a given radial shell can be well described by a log-normal PDF and a tail. The former corresponds to a nearly hydrostatic bulk component, accounting for ~99% of the volume, while the tail corresponds to high density inhomogeneities. We show that this results in a simple and robust separation of the diffuse and clumpy components of the ICM. The FWHM of the density distribution grows with radius and varies from ~0.15 dex in cluster centre to ~0.5 dex at 2r_500 in relaxed clusters. The small scatter in the width between relaxed clusters suggests that the degree of inhomogeneity is a robust characteristic of the ICM. It broadly agrees with the amplitude of density perturbations in the Coma cluster. We discuss the origin of ICM density variations in spherical shells and show that less than 20% of the width can be attributed to the triaxiality of the cluster gravitational potential. As a link to X-ray observations of real clusters we evaluated the ICM clumping factor with and without high density inhomogeneities. We argue that these two cases represent upper and lower limits on the departure of the observed X-ray emissivity from the median value. We find that the typical value of the clumping factor in the bulk component of relaxed clusters varies from ~1.1-1.2 at r_500 up to ~1.3-1.4 at r_200, in broad agreement with recent observations.Comment: 16 pages, 12 figure, accepted to MNRA

State Legal Vision of Correlation of the Concepts “Federalism” and “Federation”

In theory and practice of federation development a current problem is the correlation between the notions “federation” and “federalism”. There are a large number of definitions of both federalism and federation. The author suggests versions of interpreting these notions and sets forth the possible ways of employing them

The relation between gas density and velocity power spectra in galaxy clusters: qualitative treatment and cosmological simulations

We address the problem of evaluating the power spectrum of the velocity field of the ICM using only information on the plasma density fluctuations, which can be measured today by Chandra and XMM-Newton observatories. We argue that for relaxed clusters there is a linear relation between the rms density and velocity fluctuations across a range of scales, from the largest ones, where motions are dominated by buoyancy, down to small, turbulent scales: $(\delta\rho_k/\rho)^2 = \eta_1^2 (V_{1,k}/c_s)^2$, where $\delta\rho_k/\rho$ is the spectral amplitude of the density perturbations at wave number $k$, $V_{1,k}^2=V_k^2/3$ is the mean square component of the velocity field, $c_s$ is the sound speed, and $\eta_1$ is a dimensionless constant of order unity. Using cosmological simulations of relaxed galaxy clusters, we calibrate this relation and find $\eta_1\approx 1 \pm 0.3$. We argue that this value is set at large scales by buoyancy physics, while at small scales the density and velocity power spectra are proportional because the former are a passive scalar advected by the latter. This opens an interesting possibility to use gas density power spectra as a proxy for the velocity power spectra in relaxed clusters, across a wide range of scales.Comment: 6 pages, 3 figures, submitted to ApJ Letter

Crystal structure, thermal and electrotransport properties of NdBa1–xSrxFeCo0.5Cu0.5O5+δ (0.02 ≤ x ≤ 0.20) solid solutions

Using solid-state reactions method, the solid solutions of layered oxygen-deficient perovskites NdBa1–xSrxFeCo0.5Cu0.5O5+δ (0.02 ≤ x ≤ 0.20) were prepared; their crystal structure, thermal stability, thermal expansion, electrical conductivity and thermopower were studied. It was found that NdBa1–xSrxFeCo0.5Cu0.5O5+δ phases crystallize in tetragonal syngony (space group P4/mmm) and are p-type semiconductors, whose conductivity character at high temperatures changed to the metallic one due to evolution from the samples of so-called weakly-bonded oxygen. Partial substitution of barium by strontium in NdBaFeCo0.5Cu0.5O5+δ leads to the small decreasing of unit cell parameters, thermal stability and thermopower of NdBa1–xSrxFeCo0.5Cu0.5O5+δ solid solutions, increasing of their electrical conductivity values and slightly affects their linear thermal expansion coefficient and activation energy of electrical transport values

Relevance of application of irradiated starter cultures to production of fermented milk products

Nowadays yogurt, fermented milk products, enriched with biologically active substances, acquire increasingly important significance in people's diets. The traditional method for producing fermented milk products and yogurt is to ferment the milk using starter cultures. The purpose of this research was to figure out if it is possible to use suspensions of probiotic microbial cultures irradiated with ionizing radiation to produce yoghurt products. Liquid live suspensions of bifidobacteria and lactobacilli, as well as a mixture of bifidobacteria, lactobacilli, propionibacteria and lactic acid streptococci were taken as a research model. The goal was achieved by receiving the yoghurt products enriched with active secondary metabolites due to using the suspensions of lysed cells of different microorganisms. We studied physico-chemical and organoleptic properties of the received products after 1, 7 and 14 days of storage

Gas perturbations in cool cores of galaxy clusters: effective equation of state, velocity power spectra and turbulent heating

We present the statistical analysis of X-ray surface brightness and gas density fluctuations in cool cores of ten, nearby and bright galaxy clusters that have deep Chandra observations and show observational indications of radio-mechanical AGN feedback. Within the central parts of cool cores the total variance of fluctuations is dominated by isobaric and/or isothermal fluctuations on spatial scales ~ 10-60 kpc, which are likely associated with slow gas motions and bubbles of relativistic plasma. Adiabatic fluctuations associated with weak shocks constitute less than 10 per cent of the total variance in all clusters. The typical amplitude of density fluctuations is small, ~ 10 per cent or less on scales of ~ 10-15 kpc. Subdominant contribution of adiabatic fluctuations and small amplitude of density fluctuations support a model of gentle AGN feedback as opposed to periodically explosive scenarios which are implemented in some numerical simulations. Measured one-component velocities of gas motions are typically below 100-150 km/s on scales < 50 kpc, and can be up to ~ 300 km/s on ~ 100 kpc scales. The non-thermal energy is < 12 per cent of the thermal energy. Regardless of the source that drives these motions the dissipation of the energy in such motions provides heat that is sufficient to balance radiative cooling on average, albeit the uncertainties are large. Presented results here support previous conclusions based on the analysis of the Virgo and Perseus Clusters, and agree with the Hitomi measurements. With next generation observatories like Athena and Lynx, these techniques will be yet more powerful

Estimating turbulent velocities in the elliptical galaxies NGC 5044 and NGC 5813

The interstellar and intra-cluster medium in giant elliptical galaxies and clusters of galaxies is often assumed to be in hydrostatic equilibrium. Numerical simulations, however, show that about 5-30% of the pressure in a cluster is provided by turbulence induced by, for example, the central AGN and merger activity. We aim to put constraints on the turbulent velocities and turbulent pressure in the ICM of the giant elliptical galaxies NGC 5044 and NGC 5813 using XMM-Newton RGS observations. The magnitude of the turbulence is estimated using the Fe XVII lines at 15.01 A, 17.05 A, and 17.10 A in the RGS spectra. At low turbulent velocities, the gas becomes optically thick in the 15.01 A line due to resonant scattering, while the 17 A lines remain optically thin. By comparing the (I(17.05)+I(17.10))/I(15.01) line ratio from RGS with simulated line ratios for different Mach numbers, the level of turbulence is constrained. The measurement is limited by systematic uncertainties in the atomic data, which are at the 20-30% level. We find that the line ratio in NGC 5813 is significantly higher than in NGC 5044. This difference can be explained by a higher level of turbulence in NGC 5044. The high turbulent velocities and the fraction of the turbulent pressure support of >40% in NGC 5044, assuming isotropic turbulence, confirm that it is a highly disturbed system, probably due to an off-axis merger. The turbulent pressure support in NGC 5813 is more modest at 15-45%. The (I(17.05)+I(17.10))/I(15.01) line ratio in an optically thin plasma, calculated using AtomDB v2.0.1, is 2 sigma above the ratio measured in NGC 5044, which cannot be explained by resonant scattering. This shows that the discrepancies between theoretical, laboratory, and astrophysical data on Fe XVII lines need to be reduced to improve the accuracy of the determination of turbulent velocities using resonant scattering.Comment: 11 pages, 5 figures, accepted for publication in A&

Gas Density Fluctuations in the Perseus Cluster: Clumping Factor and Velocity Power Spectrum

X-ray surface brightness fluctuations in the core of the Perseus Cluster are analyzed, using deep observations with the Chandra observatory. The amplitude of gas density fluctuations on different scales is measured in a set of radial annuli. It varies from 8 to 12 per cent on scales of ~10-30 kpc within radii of 30-160 kpc from the cluster center and from 9 to 7 per cent on scales of ~20-30 kpc in an outer, 60-220 kpc annulus. Using a statistical linear relation between the observed amplitude of density fluctuations and predicted velocity, the characteristic velocity of gas motions on each scale is calculated. The typical amplitudes of the velocity outside the central 30 kpc region are 90-140 km/s on ~20-30 kpc scales and 70-100 km/s on smaller scales ~7-10 kpc. The velocity power spectrum is consistent with cascade of turbulence and its slope is in a broad agreement with the slope for canonical Kolmogorov turbulence. The gas clumping factor estimated from the power spectrum of the density fluctuations is lower than 7-8 per cent for radii ~30-220 kpc from the center, leading to a density bias of less than 3-4 per cent in the cluster core. Uncertainties of the analysis are examined and discussed. Future measurements of the gas velocities with the Astro-H, Athena and Smart-X observatories will directly measure the gas density-velocity perturbation relation and further reduce systematic uncertainties in these quantities.Comment: 16 pages, 15 figures, submitted to MNRAS, comments are welcom