373 research outputs found
X-ray Temperature and Mass Measurements to the Virial Radius of Abell 1413 with Suzaku
We present X-ray observations of the northern outskirts of the relaxed galaxy
cluster A1413 with Suzaku, whose XIS instrument has the low intrinsic
background needed to make measurements of these low surface brightness regions.
We excise 15 point sources superimposed on the image above a flux of \fluxunit (2--10keV) using XMM-Newton and Suzaku images of the
cluster. We quantify all known systematic errors as part of our analysis, and
show our statistical errors encompasses them for the most part. Our results
extend previous measurements with Chandra and XMM-Newton, and show a
significant temperature drop to about 3keV at the virial radius, . Our
entropy profile in the outer region () joins smoothly onto that
of XMM-Newton, and shows a flatter slope compared with simple models, similar
to a few other clusters observed at the virial radius. The integrated mass of
the cluster at the virial radius is approximately
and varies by about 30% depending on the particular method used to measure it.Comment: 32pages, 9 figures, accepted for publication in PAS
Neonatal mortality and education related inequality in cesarean births in Sub-Saharan Africa : multi-country propensity score matching and meta-analysis
Background: Sub-Saharan African (SSA) newborns are ten times more likely to die in the first month than a neonate born in a high-income country. The objective of this study was to examine the relationship between educational attainment and neonatal mortality (NM) among women with cesarean section (CS) deliveries in SSA countries. Methods: Using data from recent demographic and health surveys from 33 countries in SSA, we applied propensity score matching to estimate the effect of education attainment on post-CS neonatal mortality using a propensity-matched cohort where being educated was defined as completing at least primary school education Results: The number of reported CS births ranged from 186 in Niger to 1695 in Kenya. The odds of neonatal mortality between uneducated and educated women ranged from as low as 2.31 in Senegal to 35.5 in Zimbabwe, with a pooled overall risk for NM from all of the countries of OR 2.54 (95% CI: 1.72–3.74) and aOR 1.7 (95% CI: 1.12–2.57). From the 17,220 respondents, we successfully matched 11,162 educated respondents with 2146 uneducated respondents. Uneducated women had a 6% risk compared to a 2.9% risk among educated women for neonatal mortality, with an overall risk of 3.4%; babies from uneducated women were twice as likely to die compared to babies from educated women, RR 2.1 (95% CI, 1.69–2.52). Conclusion: Neonates from uneducated women were twice as likely to die following CS delivery than neonates from educated women. This evidence suggests that a means of achieving Sustainable Development Goal target 3.2 to lower newborn and child mortality is ensuring that everyone has access to high-quality care with efforts made at ensuring education for all and improving socio-economic conditions
Searching for Diffuse Nonthermal X-Rays from the Superbubbles N11 and N51D in the Large Magellanic Cloud
We report on observations of the superbubbles (SBs) N11 and N51D in the Large
Magellanic Cloud (LMC) with Suzaku and XMM-Newton. The interior of both SBs
exhibits diffuse X-ray emission, which is well represented by thin thermal
plasma models with a temperature of 0.2-0.3keV. The presence of nonthermal
emission, claimed in previous works, is much less evident in our careful
investigation. The 3-sigma upper limits of 2-10keV flux are
3.6*10^{-14}ergs/cm^2/s and 4.7*10^{-14}ergs/cm^2/s for N11 and N51D,
respectively. The previous claims of the detection of nonthermal emission are
probably due to the inaccurate estimation of the non X-ray background. We
conclude that no credible nonthermal emission has been detected from the SBs in
the LMC, with the exception of 30 Dor C.Comment: 9 pages, accepted for publication in ApJ
X-ray Spectroscopy of the Core of the Perseus Cluster with Suzaku: Elemental Abundances in the Intracluster Medium
The results from Suzaku observations of the central region of the Perseus
cluster are presented. Deep exposures with the X-ray Imaging Spectrometer
provide high quality X-ray spectra from the intracluster medium. X-ray lines
from helium-like Cr and Mn have been detected significantly for the first time
in clusters. In addition, elemental abundances of Ne, Mg, Si, S, Ar, Ca, Fe,
and Ni are accurately measured within 10' (or 220 kpc) from the cluster center.
The relative abundance ratios are found to be within a range of 0.8-1.5 times
the solar value. These abundance ratios are compared with previous
measurements, those in extremely metal-poor stars in the Galaxy, and
theoretical models.Comment: 10 pages, 3 figures, accepted for ApJ
X-ray observations of the galaxy cluster Abell 2029 to the virial radius
We present Suzaku observations of the galaxy cluster Abell 2029, which
exploit Suzaku's low particle background to probe the ICM to radii beyond those
possible with previous observations (reaching out to the virial radius), and
with better azimuthal coverage. We find significant anisotropies in the
temperature and entropy profiles, with a region of lower temperature and
entropy occurring to the south east, possibly the result of accretion activity
in this direction. Away from this cold feature, the thermodynamic properties
are consistent with an entropy profile which rises, but less steeply than the
predictions of purely gravitational hierarchical structure formation. Excess
emission in the northern direction can be explained due to the overlap of the
emission from the outskirts of Abell 2029 and nearby Abell 2033 (which is at
slightly higher redshift). These observations suggest that the assumptions of
spherical symmetry and hydrostatic equilibrium break down in the outskirts of
galaxy clusters, which poses challenges for modelling cluster masses at large
radii and presents opportunities for studying the formation and accretion
history of clusters.Comment: 15 pages, 14 figures. Accepted for publication in the Monthly Notices
of the Royal Astronomical Societ
Suzaku X-ray Imaging of the Extended Lobe in the Giant Radio Galaxy NGC6251 Associated with the Fermi-LAT Source 2FGLJ1629.4+8236
We report the results of a Suzaku X-ray imaging study of NGC6251, a nearby
giant radio galaxy with intermediate FR I/II radio properties. Our pointing
direction was centered on the gamma -ray emission peak recently discovered with
Fermi-LAT around the position of the north-west radio lobe 15 arcmin offset
from the nucleus. After subtracting two "off-source" pointings adjacent to the
radio lobe, and removing possible contaminants in the XIS field of view, we
found significant residual X-ray emission most likely diffuse in nature. The
spectrum of the excess X-ray emission is well fit by a power law with photon
index \Gamma = 1.90 +- 0.15 and a 0.5 - 8 keV flux of 4 x 10^{-13} erg cm^{-2}
s^{-1}. We interpret this diffuse X-ray emission component as being due to
inverse-Compton up-scattering of the cosmic microwave background photons by
ultrarelativistic electrons within the lobe, with only a minor contribution
from the beamed emission of the large-scale jet. Utilizing archival radio data
for the source, we demonstrate by means of broad-band spectral modeling that
the -ray flux of the Fermi-LAT source 2FGL J1629.4+8236 may well be accounted
for by the high-energy tail of the inverse-Compton continuum of the lobe. Thus,
this claimed association of gamma-rays from the north-west lobe of NGC6251,
together with the recent Fermi-LAT imaging of the extended lobes of Centaurus
A, indicates that particles may be efficiently (re-)accelerated up to
ultrarelativistic energies within extended radio lobes of nearby radio galaxies
in general.Comment: 19 pages, 4 figures, accepted for publication in the Ap
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