961 research outputs found
Constraints on hot metals in the Vicinity of the Galaxy
We have searched for evidence of soft X-ray absorption by hot metals in the
vicinity of the Galaxy in the spectra of a small sample of fifteen Type I AGN
observed with the high resolution X-ray gratings on board Chandra. This is an
extension of our previous survey of hot OVII and OVIII absorbing gas in the
vicinity of the Galaxy. The strongest absorption signatures within a few
hundred km/s of their rest-frame energies are most likely due to warm absorbing
outflows from the nearest AGN, which are back-lighting the local hot gas. We
emphasize that absorption signatures in the spectra of some distant AGN that
are kinematically consistent with the recessional velocity of the AGN are most
likely to be due to hot local gas. Along the sightline towards PG 1211+143, PDS
456 and MCG-6-30-15 there is a very large absorbing Fe column density which is
kinematically consistent with absorption by hot, local Fe. The sightlines to
these three AGN pass through the limb of the Northern Polar Spur (NPS), a local
bubble formed from several supernovae which, if rich in Fe, may account for a
large local Fe column.
We obtain limits on the column density of local, highly ionized N, Ne, Mg, Si
along all of the sightlines in our sample. We correlate the column density
limits with those of highly ionized O along the same sightlines. Assuming the
hot local gas is in collisionally ionized equilibrium, we obtain limits on the
temperature and relative abundances of the metals in the hot local gas. Our
limits on the ionic column densities in the local hot gas seem to be consistent
with those observed in the hot halo gas of edge-on normal spiral galaxies.Comment: 9 pages,2 figures, MNRAS (accepted
NGC 4388: A Test Case for Relativistic Disk Reflection and Fe K Fluorescence Features
We present a new analysis of the Suzaku X-ray spectrum of the Compton-thin
Seyfert 2 galaxy NGC 4388. The spectrum above 2 keV can be described by a
remarkably simple and rather mundane model, consisting of a uniform, neutral
spherical distribution of matter, with a radial column density of cm, and an Fe abundance of
relative to solar. The model does not require any
phenomenological adjustments to self-consistently account for the low-energy
extinction, the Fe K and Fe K fluorescent emission lines, the Fe
K edge, and the Compton-scattered continuum from the obscuring material. The
spherical geometry is not a unique description, however, and the
self-consistent, solar abundance MYTORUS model, applied with toroidal and
non-toroidal geometries, gives equally good descriptions of the data. In all
cases, the key features of the spectrum are so tightly locked together that for
a wide range of parameters, a relativistic disk-reflection component
contributes no more than 2% to the net spectrum in the 2-20 keV band. We
show that the commonly invoked explanations for weak X-ray reflection features,
namely a truncated and/or very highly ionized disk, do not work for NGC 4388.
If relativistically-broadened Fe K lines and reflection are ubiquitous
in Seyfert 1 galaxies, they should also be ubiquitous in Compton-thin Seyfert 2
galaxies. The case of NGC 4388 shows the need for similar studies of more
Compton-thin AGN to ascertain whether this is true.Comment: MNRAS accepted. 21 pages, 7 figures, 4 tables; Appendix with
historical notes and 1 table. This version: Corrected minor typo and
affiliatio
The Ubiquity and Magnitude of Large FeK Equivalent Widths in AGN Extended Regions
Narrow Fe K fluorescent emission lines arising at kpc-scale
separations from the nucleus have only been detected in a few AGN. The
detections require that the extended line emission be spatially resolved and
sufficiently bright. Compared to narrow Fe K lines arising closer to
the nucleus, they have much lower fluxes but show substantially larger
equivalent widths, EW. We show that, in the optically-thin
limit, a purely analytical argument naturally predicts large, EW1 keV, values for such lines, regardless of the details of
equivalent hydrogen column density, , or reprocessor geometry. Monte Carlo
simulations corroborate this result and show that the simple analytic EW prescription holds up to higher approaching the Compton-thick
regime. We compare to observations from the literature and discuss
that our results are consistent with the large EW values
reported for local AGN, for which the line is detected in extended, up to
kpc-scale, regions. We argue that large EW from
kpc-scale regions in AGN should be ubiquitous, because they do not depend on
the absolute luminosity of the central X-ray source, and are measured only
against the scattered continuum. We predict values to be of the order of
1 keV or larger, even for covering factors 1, and for arbitrarily
small column densities. We propose that the large-scale molecular material that
is now routinely being detected with the Atacama Large Millimeter/Submillimeter
Array (ALMA) may act as an extended X-ray scattering reprocessor giving rise to
kpc-scale Fe K emission.Comment: Accepted for publication in Physical Review D. 9 pages, 6 figure
A Highly Doppler Blueshifted Fe-K Emission Line in the High-Redshift QSO PKS 2149-306
We report the results from an \asca observation of the QSO PKS 2149-306
(z=2.345). We detect an emission line centered at keV in the quasar
frame. Line emission at this energy has not been observed in any other active
galaxy or quasar to date. We present evidence rejecting the possibility that
this line is the result of instrumental artifacts, or a serendipitous source.
The most likely explanation is blueshifted Fe-K emission (the EW is 300+/-200
eV, QSO frame). Bulk velocities of the order of 0.75c are implied by the data.
We show that Fe-K line photons originating in an accretion disk and
Compton-scattering off a leptonic can account for the emission line. Curiously,
if the emission-line feature recently discovered in another quasar PKS
0637752, , is blueshifted Ovii, the Doppler factor is the same
(~2.7) for both.Comment: 15 pages plus 3 figures. Latex with separate .ps files (Accepted by
Astrophysical Journal Letters
Effects of Economic and Population Factors on Health Expenditures: Special Case of Pakistan
This paper aims to explore the factors affecting the health care expenditures of Pakistan by employing the Multivariate techniques for the annual data series from 1960 to 2010 .The variables we considered are Gross Domestic Product (GDP) as an economic indicator, Population of age 65 and above (P≥65), Population of age 0 to 14 (P(0-14)), Life expectancy at Birth (LE), Crude Birth rate (CBR) and population growth rate (GR) as population indicator and Total Health Expenditure (THE) as an influencing factor. Multiple regression considering Total Health Expenditure (THE) is applied as dependent on the variables mentioned above. Since Variance Inflation Factor (VIF) for all independent variables are very high, the smallest VIF is around 11 goes up to 65. The results obtained by Principal components reveal the effect of population structure and the age factor effect oppositely on Total Health Expenditures (THE). Factor Analysis suggests that the behavior of Health Expenditures is common with Gross Domestic Product (GDP), population of age 65 and above (P≥65) and life expectancy at Birth (LE) in Pakistan while population of age 0 to 14 (P (0-14)), population growth rate (GR) and Crude Birth rate (CBR) are moving in opposite direction i.e. as GDP, P≥65 and LE of Pakistan increases P (0-14), GR and CBR will decreases
Inflammatory myofibroblastic tumor of the lung in an adolescent boy
Inflammatory myofibroblastic tumors of the lung are rare, here, an unusual case is described. A 14-year-old boy presented with a history of weight loss and clubbing and was found to have a solitary circumscribed mass in right lower lobe treated with lobectomy. This case indicates the need for early and complete removal of the inflammatory myofibroblastic tumor of the lung
MOLECULAR CHARACTERIZATION BY USING RANDOM AMPLIFIED POLYMORPHIC DNA (RAPD) ANALYSIS OF SALMONELLA ENTERITIDIS ISOLATES RECOVERED FROM AVIAN AND HUMAN SOURCES
Random amplified polymorphic DNA (RAPD) analysis was applied for molecular characterization of five Salmonella enteritidis strains from different avian sources and human cases of infection. A total of 16 primers were used and only five primers showed good discriminatory power for all five isolates. Dendrogram showed a common lineage among all five isolates. There was a close genetic relationship among isolates of eggs and human sources, while there was less pronounced homology among isolates of broiler meat and human sources. On the basis of results we have found that an endemic strain of S. enteritidis is prevalent between the poultry derived food and humans which gives us an insight to genetic diversity of S. enteritidis from these sources
Probing the unified model in NGC 7314
We present a study of the complex absorbed X-ray spectrum of the Narrow Line
Seyfert 1 galaxy NGC 7314. We collected available public X-ray data from the
archives of XMM-Newton, Suzaku, and ASCA. The spectra were analyzed using the
fitting package SPEX. We find evidence of intrinsic neutral and ionized
absorption in the XMM-Newton EPIC-pn spectrum. The ionized gas presents three
significantly distinct ionization phases, although its kinematic properties
could not be disentangled. At least two of these phases are also detected in
the RGS spectrum, although with less significance due to the low statistics.
The ASCA and Suzaku spectra show larger neutral absorption but no ionized gas
signatures. The Fe Kalpha emission line is detected in all the observations
and, additionally, Fe XXVI in the EPIC-pn spectrum, and Fe Kbeta in the Suzaku
XIS spectrum. Using this observational evidence we construct a consistent
picture of the geometry of the system in the context of the unified model of
active galactic nuclei. The different observational properties are thus
interpreted as clouds of neutral gas moving across our line of sight, which
would be grazing a clumpy dusty torus.Comment: 9 pages, 8 figures. Accepted for publication in Astronomy and
Astrophysic
Simultaneous X-ray and UV spectroscopy of the Seyfert 1 galaxy NGC 5548.II. Physical conditions in the X-ray absorber
We present the results from a 500 ks Chandra observation of the Seyfert 1
galaxy NGC 5548. We detect broadened emission lines of O VII and C VI in the
spectra, similar to those observed in the optical and UV bands. The source was
continuously variable, with a 30 % increase in luminosity in the second half of
the observation. No variability in the warm absorber was detected between the
spectra from the first 170 ks and the second part of the observation. The
velocity structure of the X-ray absorber is consistent with the velocity
structure measured simultaneously in the ultraviolet spectra. We find that the
highest velocity outflow component, at -1040 km/s, becomes increasingly
important for higher ionization parameters. This velocity component spans at
least three orders of magnitude in ionization parameter, producing both highly
ionized X-ray absorption lines (Mg XII, Si XIV) as well as UV absorption lines.
A similar conclusion is very probable for the other four velocity components.
Based upon our observations, we argue that the warm absorber probably does not
manifest itself in the form of photoionized clumps in pressure equilibrium with
a surrounding wind. Instead, a model with a continuous distribution of column
density versus ionization parameter gives an excellent fit to our data. From
the shape of this distribution and the assumption that the mass loss through
the wind should be smaller than the accretion rate onto the black hole, we
derive upper limits to the solid angle as small as 10^{-4} sr. From this we
argue that the outflow occurs in density-stratified streamers. The density
stratification across the stream then produces the wide range of ionization
parameter observed in this source. Abridged.Comment: 21 pages, 12 figures accepted for publication in A&
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