223 research outputs found
Optical and radio properties of extragalactic radio sources with recurrent jet activity
We present a sample of 74 radio sources with recurrent jet activity. The
sample consists of 67 galaxies, 2 quasars and 5 unidentified sources, selected
from the published data or are newly recognized. The sample's redshift range is
0.002 < z < 0.7 and the size of inner and outer structures varies from 0.02 to
4248 kpc. We analyse the optical and radio properties of the sample and compare
them with the characteristics of ordinary one-off FRII radio sources. With the
help of stellar population modelling, we derive black hole masses and stellar
masses of host galaxies of 35 restarting radio sources, finding that the black
hole masses in restarting radio sources are comparable to those of typical
single-cycle FRII radio sources. The obtained median values of log M are
8.58 and 8.62 M Unlike the black hole masses, the stellar masses in
restarting radio sources tend to be smaller than in the FRII sources. Although
the stellar populations of the hosts of recurrent activity sources are
dominated by old stars, a significant fraction of young stars can be observed
as well. Based on the Sloan Digital Sky Survey photometric observations, we
also analyse the morphology of the host galaxies and obtained significantly
smaller concentration indices for the restarting radio sources when compared to
the classical FRII hosts. This effect can be interpreted as a result of
frequent merger events in the history of host galaxies of restarting radio
sources.Comment: 21 pages, 17 figure
Forces and atomic relaxations in the pSIC approach with ultrasoft pseudopotentials
We present the scheme that allows for efficient calculations of forces in the
framework of pseudopotential self-interaction corrected (pSIC) formulation of
the density functional theory. The scheme works with norm conserving and also
with ultrasoft pseudopotentials and has been implemented in the plane-wave
basis code {\sc quantum espresso}. We have performed tests of the internal
consistency of the derived expressions for forces considering ZnO and CeO
crystals. Further, we have performed calculations of equilibrium geometry for
LaTiO, YTiO, and LaMnO perovskites and also for Re and Mn pairs in
silicon. Comparison with standard DFT and DFT+U approaches shows that in the
cases where spurious self-interaction matters, the pSIC approach predicts
different geometry, very often closer to the experimental data.Comment: 11 pages, 2 figure
Growth Kinetics of Vitamin C Crystals in a Batch L(+)-Ascorbic Acid – Methanol – Ethanol – Water System: Size Independent Growth Model Approach
The experimental data concerning growth kinetics of vitamin C (L(+)-ascorbic acid, LAA) crystals in a seeded and cooling batch mass crystallization process realized in a four–compound: L(+)-ascorbic acid–methanol–ethanol–water system are reported. Influences of initial composition of solution and its linear cooling rate on “average, effective” values of crystal linear growth rate were examined. Small divergences between LAA crystal size distributions (CSDs) data from granulometric analysis and Coulter counter were interpreted theoretically and discussed. Linear growth rates of crystals in a batch crystallizer were acquired with a proposed by Nývlt indirect method, based on the analysis of population density n(L) data in a MSMPR (mixed suspension mixed product removal) crystallizer. Size–independent growth (SIG) kinetics was assumed. It can be concluded, that the largest and the most uniform particles of purified, crystalline vitamin C correspond to higher initial concentration of L(+)-ascorbic acid in a solution and lower cooling rate applied
Effect of electron correlations in Pd, Ni, and Co monowires
We investigated the effect of mean-field electron correlations on the band
electronic structure of Co, Ni, and Pd ultra-thin monatomic nanowires, at the
breaking point, by means of density-functional calculations in the
self-interaction corrected LDA approach (LDA+SIC) and alternatively by the
LDA+ scheme. We find that adding static electron correlations increases the
magnetic moment in Pd monowires, but has negligible effect on the magnetic
moment in Co and Ni. Furthermore, the number of -dominated conductance
channels decreases somewhat compared to the LDA value, but the number of
-dominated channels is unaffected, and remains equal to one per spin.Comment: to appear in PR
On the Merging Cluster Abell 578 and Its Central Radio Galaxy 4C +67.13
Here we analyze radio, optical, and X-ray data for a peculiar cluster Abell
578. This cluster is not fully relaxed and consists of two merging sub-systems.
The brightest cluster galaxy, CGPG 0719.8+6704, is a pair of interacting
ellipticals with projected separation 10 kpc, the brighter of which hosts
the radio source 4C +67.13. The Fanaroff-Riley type-II radio morphology of 4C
+67.13 is unusual for central radio galaxies in local Abell clusters. Our new
optical spectroscopy revealed that both nuclei of the CGPG 0719.8+6704 pair are
active, albeit at low accretion rates corresponding to the Eddington ratio
(for the estimated black hole masses of and ). The gathered X-ray ({\it Chandra})
data allowed us to confirm and to quantify robustly the previously noted
elongation of the gaseous atmosphere in the dominant sub-cluster, as well as a
large spatial offset (\,kpc projected) between the position of the
brightest cluster galaxy and the cluster center inferred from the modeling of
the X-ray surface brightness distribution. Detailed analysis of the brightness
profiles and temperature revealed also that the cluster gas in the vicinity of
4C\,+67.13 is compressed (by a factor of about ) and heated (from
\,keV up to 2.7\,keV), consistent with the presence of a weak shock
(Mach number ) driven by the expanding jet cocoon. This would then
require the jet kinetic power of the order of \,erg\,s,
implying either a very high efficiency of the jet production for the current
accretion rate, or a highly modulated jet/accretion activity in the system.Comment: 12 pages, 11 figures, accepted for publication in Ap
Serum levels of IL-6 type cytokines and soluble IL-6 receptors in active B-cell chronic lymphocytic leukemia and in cladribine induced remission.
We have investigated the serum concentrations of interleukin-6 (IL-6) and two IL-6 family cytokines-oncostatin M (OSM) and leukemia inhibitory factor (LIF)-in 63 patients with B-cell chronic lymphocytic leukemia (B-CLL) and 17 healthy controls using the enzyme-linked immunosorbent assay (ELISA) method. Simultaneously, we measured the serum levels of the soluble forms of two subunits of the IL-6 receptor complex-ligand binding glycoprotein 80 (sIL-6R) and glycoprotein 130 (sgp130). The cytokines and receptors were evaluated in 25 untreated patients and 38 patients treated with cladribine (2-CdA), as well as in 17 healthy controls. We have correlated the serum levels of these proteins with Rai's clinical stage of the disease, the response to 2-CdA treatment and some hematological parameters. We have also evaluated the correlation of the IL-6 serum level with the concentration of OSM and IL-6 soluble receptors. IL-6 was measurable in 62/63 (98.4%), OSM in 20/25 (80%) of untreated and 14/38 (37.8%) of the treated patients. sIL-6R and sgp130 were detectable in all 63 patients and LIF in none of the CLL patients. IL-6 serum level in untreated patients was not significantly different as compared to its concentration in the control group (P>0.05). However, in the patients treated with 2-CdA the IL-6 level was significantly lower (P<0.02), and the lowest concentration was found in the patients with complete remission (CR; median 1.4pg/ml; P<0.02). The concentration of sIL-6R was significantly higher in untreated (median 61.8 ng/ml) and treated (median 50.1 ng/ml) CLL patients when compared to normal persons (median 41.2 ng/ml; P=0.04; P<0.001, respectively). There was no difference between the sIL-6R levels in the patients with CR and the healthy controls. In non-responders sIL-6R concentration was the highest and similar to its level in the untreated patients. OSM level was higher in the untreated patients (median 1.8pg/ml) than in the normal controls (median 0.0pg/ml; P<0.001) and in the CR patients (median 0.0pg/ml; P<0.03). The serum concentration of sgp130 was similar in the untreated (median 480 pg/ml) and treated (median 470 pg/ml) patients, as well as in the healthy persons (median 420 pg/ml; P>0.05). We have found significant positive correlation between the levels of sIL-6R and the lymphocytes count in CLL patients (p=0.423; P<0.001). In addition, sIL-6R and OSM serum concentrations correlated also with CLL Rai stage. In conclusion, the serum level of IL-6, OSM and sIL-6R, but not LIF and sgp130, are useful indicators of CLL activity
On the Interaction of the PKS B1358-113 Radio Galaxy with the Abell 1836 Cluster
[abridged] Here we present the analysis of multifrequency data gathered for
the FRII radio galaxy PKS B1358-113, hosted in the brightest cluster galaxy of
Abell 1836. The galaxy harbors one of the most massive black holes known to
date and our analysis of the optical data reveals that this black hole is only
weakly active. Based on new Chandra and XMM-Newton X-ray observations and
archival radio data we derive the preferred range for the jet kinetic
luminosity erg s. This is above the values
implied by various scaling relations proposed for radio sources in galaxy
clusters, being instead very close to the maximum jet power allowed for the
given accretion rate. We constrain the radio source lifetime as
Myrs, and the total amount of deposited jet energy \,ergs. The detailed analysis of the X-ray data provides indication for
the presence of a bow-shock driven by the expanding radio lobes into the Abell
1836 cluster environment, with the corresponding Mach number . This,
together with the recently growing evidence that powerful FRII radio galaxies
may not be uncommon in the centers of clusters at higher redshifts, supports
the idea that jet-induced shock heating may indeed play an important role in
shaping the properties of clusters, galaxy groups, and galaxies in formation.
We speculate on a possible bias against detecting jet-driven shocks in poorer
environments, resulting from an inefficient electron heating at the shock
front, combined with a relatively long electron-ion equilibration timescale.Comment: Version accepted to Ap
Signatures of the disk-jet coupling in the Broad-line Radio Quasar 4C+74.26
Here we explore the disk-jet connection in the broad-line radio quasar
4C+74.26, utilizing the results of the multiwavelength monitoring of the
source. The target is unique in that its radiative output at radio wavelengths
is dominated by a moderately-beamed nuclear jet, at optical frequencies by the
accretion disk, and in the hard X-ray range by the disk corona. Our analysis
reveals a correlation (local and global significance of 96\% and 98\%,
respectively) between the optical and radio bands, with the disk lagging behind
the jet by days. We discuss the possible explanation for this,
speculating that the observed disk and the jet flux changes are generated by
magnetic fluctuations originating within the innermost parts of a truncated
disk, and that the lag is related to a delayed radiative response of the disk
when compared with the propagation timescale of magnetic perturbations along
relativistic outflow. This scenario is supported by the re-analysis of the
NuSTAR data, modelled in terms of a relativistic reflection from the disk
illuminated by the coronal emission, which returns the inner disk radius
. We discuss the global energetics in
the system, arguing that while the accretion proceeds at the Eddington rate,
with the accretion-related bolometric luminosity erg s , the jet total kinetic energy
erg s, inferred from the dynamical
modelling of the giant radio lobes in the source, constitutes only a small
fraction of the available accretion power.Comment: 9 pages and 6 figures, ApJ accepte
Growth Kinetics of Vitamin C Crystals in a Batch L(+)-Ascorbic Acid – Methanol – Ethanol – Water System: Size Independent Growth Model Approach
The experimental data concerning growth kinetics of vitamin C (L(+)-ascorbic acid, LAA) crystals in a seeded and cooling batch mass crystallization process realized in a four–compound: L(+)-ascorbic acid–methanol–ethanol–water system are reported. Influences of initial composition of solution and its linear cooling rate on “average, effective” values of crystal linear growth rate were examined. Small divergences between LAA crystal size distributions (CSDs) data from granulometric analysis and Coulter counter were interpreted theoretically and discussed. Linear growth rates of crystals in a batch crystallizer were acquired with a proposed by Nývlt indirect method, based on the analysis of population density n(L) data in a MSMPR (mixed suspension mixed product removal) crystallizer. Size–independent growth (SIG) kinetics was assumed. It can be concluded, that the largest and the most uniform particles of purified, crystalline vitamin C correspond to higher initial concentration of L(+)-ascorbic acid in a solution and lower cooling rate applied
Precursor flares in OJ 287
We have studied three most recent precursor flares in the light curve of the
blazar OJ 287 while invoking the presence of a precessing binary black hole in
the system to explain the nature of these flares. Precursor flare timings from
the historical light curves are compared with theoretical predictions from our
model that incorporate effects of an accretion disk and post-Newtonian
description for the binary black hole orbit. We find that the precursor flares
coincide with the secondary black hole descending towards the accretion disk of
the primary black hole from the observed side, with a mean z-component of
approximately z_c = 4000 AU. We use this model of precursor flares to predict
that precursor flare of similar nature should happen around 2020.96 before the
next major outburst in 2022.Comment: to appear in the Astrophysical Journa
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