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

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&

X-ray line formation in the spectrum of SS 433

The mechanisms for the formation of X-ray lines in the spectrum of SS 433 are investigated by taking into account the radiative transfer inside the jets. The results of Monte Carlo numerical simulations are presented. The effect of a decrease in line intensity due to scattering inside the jet turns out to be pronounced, but it does not exceed 60% in magnitude on the entire grid of parameters. The line broadening due to scattering, nutational motion, and the contribution of satellites can lead to overestimates of the jet opening angle $\Theta$ from the line widths in Chandra X-ray observations. The fine structure of the lines turns out to be very sensitive to the scattering effects. This makes its investigation by planned X-ray observatories equipped with high-resolution spectrometers (primarily Astro-H) a powerful tool for diagnosing the parameters of the jets in SS 433.Comment: 23 pages, 14 figures, to be published in Astronomy Letters, v. 38, n. 7, p. 443 (2012

External and internal culture of students of the Ural state medical university

The article analyzes the data of an anonymous survey among students of the Ural State Medical University (UGMU) to determine the level of external and internal culture of students. It is determined that the level of students' culture is at the middle level, students have a correct understanding of the external and internal culture of behavior, but in practice they are always guided by their convictions. The best level of understanding of the culture among respondents show students of the dental faculty.В статье проанализированы данные анонимного анкетирования студентов Уральского Государственного Медицинского Университета (УГМУ) для определения уровня внешней и внутренней культуры обучающихся. Определено, что уровень культуры студентов находится на среднем уровне, обучающиеся имеют правильное представление о внешней и внутренней культуре поведения, но на практике всегда руководствуются своими убеждениями. Наилучший уровень представления о культуре по опросам показали студенты стоматологического факультет

Polarization of X-ray lines from galaxy clusters and elliptical galaxies - a way to measure tangential component of gas velocity

We study the impact of gas motions on the polarization of bright X-ray emission lines from the hot intercluster medium (ICM). The polarization naturally arises from resonant scattering of emission lines owing to a quadrupole component in the radiation field produced by a centrally peaked gas density distribution. If differential gas motions are present then a photon emitted in one region of the cluster will be scattered in another region only if their relative velocities are small enough and the Doppler shift of the photon energy does not exceed the line width. This affects both the degree and the direction of polarization. The changes in the polarization signal are in particular sensitive to the gas motions perpendicular to the line of sight. We calculate the expected degree of polarization for several patterns of gas motions, including a slow inflow expected in a simple cooling flow model and a fast outflow in an expanding spherical shock wave. In both cases, the effect of non-zero gas velocities is found to be minor. We also calculate the polarization signal for a set of clusters, taken from large-scale structure simulations and evaluate the impact of the gas bulk motions on the polarization signal. We argue that the expected degree of polarization is within reach of the next generation of space X-ray polarimeters.Comment: 25 pages, 18 figures, accepted to MNRA

Phenotypic Manifestation of Homozygous Partial Deletion of the Chromosome 1 Segment Spanning Cfhr3 Region

This article presents two clinical cases of patients with a homozygous deletion of segment of chromosome 1, which covers regions of genes associated with complement factor H, in particular CFHR3. Patients underwent in-depth clinical studies, heredity assessment, laboratory, instrumental and genetic diagnostics. The first clinical case describes a clinical case with deleted chromosome 1 segment in a 9-year-old girl who was diagnosed with atypical hemolytic-uremic syndrome. This is a complement-dependent disease that affects both adults and children. It is known that a defect in any proteins included in the alternative complement activation pathway can lead to atypical hemolytic-uremic syndrome. However, this syndrome is most often caused by defects in chromosome 1 region, including gene sequences associated with complement factor H-CFHR1 and CFHR3. Modern treatment of atypical hemolytic uremic syndrome involves targeted pathogenetic treatment, therefore, the genetic diagnosis seems to be a necessary step for differential diagnosis and confirmation. The patient had fairly typical clinical symptoms, including signs of thrombotic microangiopathy, thrombocytopenia, hemolytic anemia and increasing renal failure. It is also known that her mother had congenital hydronephrosis, and the pregnancy proceeded against a background of ureaplasma, mycoplasma, cytomegalovirus infection, chronic pyelonephritis, and preeclampsia. The second clinical case of a deleted chromosome 1 region, involving the CFHR3 gene, is a description of the disease in a boy of 8 years old, while the disease manifested with alopecia at the age of 4. Intermittent alopecia was the main symptom, while there were no signs of renal failure, thrombocytopenic purpura, and other symptoms characteristic of atypical hemolytic-uremic syndrome. The boy also revealed some congenital defects of the urinary system: Bladder diverticulum, unilateral ureterohydronephrosis, and bilateral dilatation of the pyelocaliceal system. The detected genetic defect is usually associated with atypical hemolytic uremic syndrome. However, the phenotype, i.e., clinical manifestations, determined a completely different diagnosis-primary immunodeficiency, a group of complement defects, and a deficiency of complement factor H-related protein. After analyzing the given clinical cases, we can conclude that clinical manifestations may vary significantly in carriers of same gene mutations. This suggests that there are additional factors (genetic or environmental) that can influence the formation of various phenotypic manifestations of this pathology. © 2020 Russian Association of Allergologists and Clinical Immunologists, St. Petersburg Regional Branch (SPb RAACI). All rights reserved

Upper limits on the isotropic diffuse flux of cosmic PeV photons from Carpet-2 observations

Isotropic diffuse gamma-ray flux in the PeV energy band is an important tool for multimessenger tests of models of the origin of high-energy astrophysical neutrinos and for new-physics searches. So far, this flux has not yet been observed. Carpet-2 is an air-shower experiment capable of detecting astrophysical gamma rays with energies above 0.1 PeV. Here we report the upper limits on the isotropic gamma-ray flux from Carpet-2 data obtained in 1999-2011 and 2018-2022. These results, obtained with the new statistical method based on the shape of the muon-number distribution, summarize Carpet-2 observations as the upgraded installation, Carpet-3, starts its operation.Comment: 5 pages, 3 figures, JETPL.cls; V2: references added, version accepted by JETP Letter