195 research outputs found
The history of the iron K-alpha line profile in the Piccinotti AGN ESO198-G24
This paper presents ASCA (July 1997), XMM-Newton (December 2000) and BeppoSAX
(January 2001) observations of the Piccinotti Seyfert 1 galaxy ESO198-G24. The
BeppoSAX 0.1-200 keV spectrum exhibits reprocessing features, probably produced
by an X-ray illuminated, relativistic accretion disk subtending a solid angle
\~2 pi. During the XMM-Newton observation the fluorescent iron K-alpha line
profile (centroid energy E~6.4 keV) was broad and twice as bright as in the
BeppoSAX observation. An additional emission feature (E~5.7 keV), detected at
the 96.3% confidence level, may be part of a relativistic, double-peaked
profile. By contrast, in the earlier ASCA observation the line profile is
dominated by a remarkably narrow "core" (intrinsic width <50 eV). If this
component is produced by reflection off the inner surface of a molecular torus,
its large Equivalent Width (~300 eV) most likely represents the "echo" of a
previously brighter flux state, in agreement with the dynamical range covered
by the historical X-ray light curve in ESO198-G24.Comment: 9 Latex pages, 11 figures, To appear in Astronomy & Astrophysic
Chelyabinsk meteorite explains unusual spectral properties of Baptistina Asteroid Family
We investigated the spectral and compositional properties of Chelyabinsk
meteorite to identify its possible parent body in the main asteroid belt. Our
analysis shows that the meteorite contains two spectrally distinct but
compositionally indistinguishable components of LL5 chondrite and shock
blackened/impact melt material. Our X-ray diffraction analysis confirms that
the two lithologies of the Chelyabinsk meteorite are extremely similar in modal
mineralogy. The meteorite is compositionally similar to LL chondrite and its
most probable parent asteroid in the main belt is a member of the Flora family.
Intimate mixture of LL5 chondrite and shock blackened/impact melt material from
Chelyabinsk provides a spectral match with (8) Flora, the largest asteroid in
the Flora family. The Baptistina family and Flora family overlap each other in
dynamical space. Mineralogical analysis of (298) Baptistina and 9 small family
members shows that their surface compositions are similar to LL chondrites,
although their absorption bands are subdued and albedos lower when compared to
typical S-type asteroids. A range of intimate mixtures of LL5 chondrite and
shock blackened/impact melt material from Chelyabinsk provides spectral matches
for all these BAF members. We suggest that the presence of a significant
shock/impact melt component in the surface regolith of BAF members could be the
cause of lower albedo and subdued absorption bands. The parent asteroid of BAF
was either a member of the Flora family or had the same basic composition as
the Floras (LL Chondrite). The shock pressures produced during the impact event
generated enough impact melt or shock blackening to alter the spectral
properties of BAF, but keep the BAF composition largely unchanged.Comment: 48 pages, 11 figures, 7 table
Physiological deterioration in the Emergency Department: the SNAP40-ED study
Continuous novel ambulatory monitoring may detect deterioration in Emergency Department (ED) patients more rapidly, prompting treatment and preventing adverse events. Single-centre, open-label, prospective, observational cohort study recruiting high/medium acuity (Manchester triage category 2 and 3) participants, aged over 16 years, presenting to ED. Participants were fitted with a novel wearable monitoring device alongside standard clinical care (wired monitoring and/or manual clinical staff vital sign recording) and observed for up to 4 hours in the ED. Primary outcome was time to detection of deterioration. Two-hundred and fifty (250) patients were enrolled. In 82 patients (32.8%) with standard monitoring (wired monitoring and/or manual clinical staff vital sign recording), deterioration in at least one vital sign was noted during their four-hour ED stay. Overall, the novel device detected deterioration a median of 34 minutes earlier than wired monitoring (Q1, Q3 67,194; n=73, mean difference 39.48, p<0.0001). The novel device detected deterioration a median of 24 minutes (Q1, Q3 2,43; n=42) earlier than wired monitoring and 65 minutes (Q1, Q3 28,114; n=31) earlier than manual vital signs. Deterioration in physiology was common in ED patients. ED staff spent a significant amount of time performing observations and responding to alarms, with many not escalated. The novel device detected deterioration significantly earlier than standard care
Unveiling the broad band X-ray continuum and iron line complex in Mkr 841
Mkr 841 is a bright Seyfert 1 galaxy known to harbor a strong soft excess and
a variable K iron line. It has been observed during 3 different periods
by XMM for a total cumulated exposure time of 108 ks. We present in this
paper a broad band spectral analysis of the complete EPIC-pn data sets. We were
able to test two different models for the soft excess, a relativistically
blurred photoionized reflection (\r model) and a relativistically smeared
ionized absorption (\a model). The continuum is modeled by a simple cut-off
power law and we also add a neutral reflection. These observations reveal the
extreme and puzzling spectral and temporal behaviors of the soft excess and
iron line. The 0.5-3 keV soft X-ray flux decreases by a factor 3 between 2001
and 2005 and the line shape appears to be a mixture of broad and narrow
components. We succeed in describing this complex broad-band 0.5-10 keV
spectral variability using either \r or \a to fit the soft excess. Both models
give statistically equivalent results even including simultaneous BeppoSAX data
up to 200 keV. Both models are consistent with the presence of remote
reflection characterized by a constant narrow component in the data. However
they differ in the presence of a broad line component present in \r but not
needed in \a. This study also reveals the sporadic presence of relativistically
redshifted narrow iron lines.Comment: Accepted in A&A. 17 pages and 21 figure
An observational study to evaluate three pilot programmes of retesting chlamydia-positive individuals within 6â months in the South West of England
OBJECTIVES: To evaluate 3 pilot chlamydia retesting programmes in South West England which were initiated prior to the release of new National Chlamydia Screening Programme (NCSP) guidelines recommending retesting in 2014. METHODS: Individuals testing positive between August 2012 and July 2013 in Bristol (n=346), Cornwall (n=252) and Dorset (n=180) programmes were eligible for inclusion in the retesting pilots. The primary outcomes were retest within 6â
months (yes/no) and repeat diagnosis at retest (yes/no), adjusted for area, age and gender. RESULTS: Overall 303/778 (39.0%) of participants were retested within 6â
months and 31/299 (10.4%) were positive at retest. Females were more likely to retest than males and Dorset had higher retesting rates than the other areas. CONCLUSIONS: More than a third of those eligible were retested within the time frame of the study. Chlamydia retesting programmes appear feasible within the context of current programmes to identify individuals at continued risk of infection with relatively low resource and time input
XMM-Newton observation of PG 0844 + 349
In a ~ 20 ksec XMM-Newton observation the X-ray transient radio-quiet quasar
PG 0844+349 was found in a historically high state compared to previous X-ray
observations. The quasar showed a featureless spectrum with a strong soft
excess over the extrapolation of a hard power law. Comptonization models or a
broken power law with Gamma_{soft} ~ 2.75, Gamma_{hard} ~ 2.25 and a break
energy of E_{break} ~ 1.35 keV represent acceptable descriptions of the
spectral continuum. In the Comptonization models the temperature of the
Comptonizing gas is considerably lower than generally found in (broad line)
Seyfert galaxies whereas the optical depth is much higher. As a similar
behavior has been seen in NLSy1 galaxies, it might be an indicator of the
different physical conditions in these two classes of AGN. During the
XMM-Newton observation the flux of PG 0844+349 varied achromatically in a
smooth, nearly linear fashion, by ~ 25 % on time scales of a few thousand
seconds, which puts some constraints on current models of Comptonizing
accretion disk coronae.Comment: 7 pages, 4 figures. A&A accepte
X-ray variability of the Narrow Line Seyfert 1 Galaxy PKS 0558-504
We present results from several XMM-Newton observations of the radio loud
Narrow-line Seyfert 1 galaxy (NLS1) PKS 0558-504. We find evidence for strong
and persistent X-ray variability, both on short and long time-scales. On short
time scales of ~2 hours the source varies smoothly by 15-20%; long term
variations by a factor of >2 could not be resolved in the relatively short
exposures: we find the source mostly in a `low' state, in 2 out of the 11
observations in a `high state'. X-ray flares seem to be recurrent with a time
scale of ~24 ksec which, if interpreted as the Keplerian time scale in the
disc, would place the emission region just outside the last stable orbit. The
X-ray spectrum of PKS 0558-504 can be well fitted by two Comptonization
components, one at moderate temperatures of kT ~ 4.5 keV and optical depths of
\~ 2, the other at high temperatures kT > 50 keV and low optical depths < 1.0.
These parameters are, however, subject to large errors due to the inherent
degeneracy of the Comptonization models. Flux variations of the source are
caused by changes of the colder component only, the hot component with
parameters very similar to those of BLS1 galaxies, stays constant. All results
fit nicely the picture that NLS1 galaxies are lower mass objects, accreting
close to the Eddington rate emitting X-rays from a very active magnetically
powered accretion disc corona.Comment: 11 pages, 10 figures, accepted for publication in A&
The host galaxy/AGN connection. Brightness profiles of early-type galaxies hosting Seyfert nuclei
[ABRIDGED] We recently presented evidence of a connection between the
brightness profiles of nearby early-type galaxies and the properties of the AGN
they host. The radio loudness of the AGN appears to be univocally related to
the host's brightness profile: radio-loud nuclei are only hosted by ``core''
galaxies while radio-quiet AGN are only found in ``power-law'' galaxies. We
extend our analysis here to a sample of 42 nearby (V < 7000 km/s) Seyfert
galaxies hosted by early-type galaxies. We used the available HST images to
study their brightness profiles. Having excluded complex and highly nucleated
galaxies, in the remaining 16 objects the brightness profiles can be
successfully modeled with a Nuker law with a steep nuclear cusp characteristic
of ``power-law'' galaxies (with logarithmic slope 0.51 - 1.07). This result is
what is expected for these radio-quiet AGN based on our previous findings, thus
extending the validity of the connection between brightness profile and radio
loudness to AGN of a far higher luminosity. We explored the robustness of this
result against a different choice of the analytic form for the brightness
profiles, using a Sersic law. In no object could we find evidence of a central
light deficit with respect to a pure Sersic model, the defining feature of
``core'' galaxies in this modeling framework. We conclude that, regardless of
the modeling strategy, the dichotomy of AGN radio loudness can be univocally
related to the host's brightness profile. Our general results can be re-phrased
as ``radio-loud nuclei are hosted by core galaxies, while radio-quiet AGN are
found in non-core galaxies''.Comment: Accepted for publication in A&
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