10,011 research outputs found
A long hard look at MCG-6-30-15 with XMM-Newton
We present first results from a 325 ks observation of the Seyfert 1 galaxy
MCG-6-30-15 with XMM-Newton and BeppoSAX. The strong, broad, skewed iron line
is clearly detected and is well characterised by a steep emissivity profile
within 6r_g (i.e. 6GM/c^2) and a flatter profile beyond. The inner radius of
the emission appears to lie at about 2r_g, consistent with results reported
from both an earlier XMM-Newton observation of MCG-6-30-15 by Wilms et al. and
part of an ASCA observation by Iwasawa et al. when the source was in a lower
flux state. The radius and steep emissivity profile do depend however on an
assumed incident power-law continuum and a lack of complex absorption above 2.5
keV. The blue wing of the line profile is indented, either by absorption at
about 6.7 keV or by a hydrogenic iron emission line. The broad iron line flux
does not follow the continuum variations in a simple manner.Comment: 5 pages, accepted by MNRAS Letter
Next Generation Sequencing Assay for Detection of Circulating HPV DNA (cHPV-DNA) in Patients Undergoing Radical (Chemo)Radiotherapy in Anal Squamous Cell Carcinoma (ASCC).
Background: Following chemo-radiotherapy (CRT) for human papilloma virus positive (HPV+) anal squamous cell carcinoma (ASCC), detection of residual/recurrent disease is challenging. Patients frequently undergo unnecessary repeated biopsies for abnormal MRI/clinical findings. In a pilot study we assessed the role of circulating HPV-DNA in identifying "true" residual disease. Methods: We prospectively collected plasma samples at baseline (n = 21) and 12 weeks post-CRT (n = 17). Circulating HPV-DNA (cHPV DNA) was measured using a novel next generation sequencing (NGS) assay, panHPV-detect, comprising of two primer pools covering distinct regions of eight high-risk HPV genomes (16, 18, 31, 33, 35, 45, 52, and 58) to detect circulating HPV-DNA (cHPV DNA). cHPV-DNA levels post-CRT were correlated to disease response. Results: In pre-CRT samples, panHPV-detect demonstrated 100% sensitivity and specificity for HPV associated ASCC. PanHPV-detect was able to demonstrate cHPV-DNA in 100% (9/9) patients with T1/T2N0 cancers. cHPV-DNA was detectable 12 weeks post CRT in just 2/17 patients, both of whom relapsed. 1/16 patients who had a clinical complete response (CR) at 3 months post-CRT but relapsed at 9 months and 1/1 patient with a partial response (PR). PanHPV-detect demonstrated 100% sensitivity and specificity in predicting response to CRT. Conclusion: We demonstrate that panHPV-detect, an NSG assay is a highly sensitive and specific test for the identification of cHPV-DNA in plasma at diagnosis. cHPV-DNA post-treatment may predict clinical response to CRT
A long hard look at MCG-6-30-15 with XMM-Newton and BeppoSAX
We summarise the primary results from a 320 ks observation of the bright
Seyfert 1 galaxy MCG-6-30-15 with XMM-Newton and Beppo-SAX.Comment: 4 pages, 6 figures. Proc. of the meeting: "The Restless High-Energy
Universe" (Amsterdam, The Netherlands), E.P.J. van den Heuvel, J.J.M. in 't
Zand, and R.A.M.J. Wijers Ed
A softer look at MCG--6-30-15 with XMM-Newton
We present analysis and results from the Reflection Grating Spectrometer
during the 320 ks XMM observation of the Seyfert 1 galaxy MCG-6-30-15. The
spectrum is marked by a sharp drop in flux at 0.7 keV which has been
interpreted by Branduardi-Raymont et al. as the blue wing of a relativistic
OVIII emission line and by Lee at al. as a dusty warm absorber. We find that
the drop is well explained by the FeI L2,3 absorption edges and obtain
reasonable fits over the 0.32-1.7 keV band using a multizone, dusty warm
absorber model. Some residuals remain which could be due to emission from a
relativistic disc, but at a much weaker level than from any model relying on
relativistic emission lines alone. A model based on such emission lines can be
made to fit if sufficient (warm) absorption is added, although the line
strengths exceed those expected. The EPIC pn difference spectrum between the
highest and lowest flux states of the source indicates that this is a power-law
in the 3-10 keV band which, if extrapolated to lower energies, reveals the
absorption function acting on the intrinsic spectrum, provided that any
emission lines do not scale exactly with the continuum. We find that this
function matches our dusty warm absorber model well. The soft X-ray spectrum is
therefore dominated by absorption structures, with the equivalent width of any
individual emission lines in the residuals being below about 30 eV. (abridged)Comment: 8 pages, 10 figures, submitted to MNRA
XMM-Newton observations of 3C 273
A series of nine XMM-Newton observations of the radio-loud quasar 3C 273 are
presented, concentrating mainly on the soft excess. Although most of the
individual observations do not show evidence for iron emission, co-adding them
reveals a weak, broad line (EW ~ 56 eV). The soft excess component is found to
vary, confirming previous work, and can be well fitted with multiple blackbody
components, with temperatures ranging between ~40 and ~330 eV, together with a
power-law. Alternatively, a Comptonisation model also provides a good fit, with
a mean electron temperature of ~350 eV, although this value is higher when the
soft excess is more luminous over the 0.5-10 keV energy band. In the RGS
spectrum of 3C 273, a strong detection of the OVII He-alpha absorption line at
zero redshift is made; this may originate in warm gas in the local
intergalactic medium, consistent with the findings of both Fang et al. (2003)
and Rasmussen et al. (2003).Comment: 12 pages, 19 figures, accepted for publication in MNRA
Far-infrared and molecular line observations of Lynds 183 - studies of cold gas and dust
We have mapped the dark cloud L183 in the far-infrared at 100um and 200um
with the ISOPHOT photometer aboard the ISO satellite. The observations make it
possible for the first time to study the properties of the large dust grains in
L183 without confusion from smaller grains. The observations show clear colour
temperature variations which are likely to be caused by changes in the emission
properties of the dust particles. In the cloud core the far-infrared colour
temperature drops below 12K. The data allow a new determination of the cloud
mass and the mass distribution. The mass within a radius of 10 arcmin from the
cloud centre is 25 Msun. We have mapped the cloud in several molecular lines
including DCO+(2-1) and H13CO+(1-0). These species are believed to be tracers
of cold and dense molecular material and we detect a strong anticorrelation
between the DCO+ emission and the dust colour temperatures. In particular, the
DCO+(2-1) emission is not detected towards the maximum of the 100um emission
where the colour temperature rises above 15K. The H13CO+ emission follows the
DCO+ distribution but CO isotopes show strong emission even towards the 100um
peak. A comparison of the DCO+ and C18O maps shows sharp variations in the
relative intensities of the species. Morphologically the 200um dust emission
traces the distribution of dense molecular material as seen e.g. in C18O lines.
A comparison with dust column density shows that C18O is depleted by a factor
of 1.5 in the cloud core. We present results of R- and B-band starcounts. The
extinction is much better correlated with the 200um than with the 100um
emission. Based on the 200um correlation at low extinction values we deduce a
value of ~17mag for the visual extinction towards the cloud centre.Comment: to be published in A&
A high velocity ionised outflow and XUV photosphere in the narrow emission line quasar PG1211+143
We report on the analysis of a ~60 ksec XMM observation of the bright, narrow
emission line quasar PG 1211+143. Absorption lines are seen in both EPIC and
RGS spectra corresponding to H- and He-like ions of Fe, S, Mg, Ne, O, N and C.
The observed line energies indicate an ionised outflow velocity of ~24000 km
s^-1. The highest energy lines require a column density of N_H ~ 5 x 10^23
cm^-2, at an ionisation parameter of log(xi) ~ 3.4. If the origin of this high
velocity outflow lies in matter being driven from the inner disc, then the flow
is likely to be optically thick within a radius ~130 Schwarzschild radii,
providing a natural explanation for the Big Blue Bump (and strong soft X-ray)
emission in PG 1211+143.Comment: Accepted by MNRAS; Table 1 correcte
The soft X-ray absorption lines of the Seyfert 1 galaxy MCG--6-30-15
The absorption lines in the soft X-ray spectrum of MCG--6-30-15 are studied
using the Reflection Grating Spectrometer data from the 2001 XMM-Newton 320 ks
observation. A line search of the full time-averaged spectrum reveals 51
absorption lines and one emission line. The equivalent widths of the lines are
measured and the majority of the lines identified. We find lines produced by a
broad range of charge states for several elements, including almost all the
charge states oxygen and iron, suggesting a broad range of ionization
parameters is present in the warm absorber. The equivalent widths of the lines
are broadly consistent with the best fitting warm absorber models from Turner
et al (2003). The equivalent widths of the absorption lines allow confidence
limits on the column density of the species to be determined. For OVII a column
density of 10^18.36-10^18.86 cm^-2 is found. This column density of OVII, when
combined with the inferred FeI absorption, is sufficient to explain the drop in
flux at 0.7 keV as being due to absorption from the warm absorber. Fitting OI
K-edge absorption to the spectrum reveals a column of 10^17.51-10^17.67 cm^-2
of OI, suggesting an Fe:O ratio of ~1:2, consistent with the neutral iron being
in the form of iron oxide dust. Variability is seen in a few absorption lines,
but the majority of the absorption features, including the prominent absorption
edges, stay constant throughout the observation despite variability in the
continuum flux.Comment: Accepted for publication in MNRAS, 11 pages, 7 figure
The persistence landscape and some of its properties
Persistence landscapes map persistence diagrams into a function space, which
may often be taken to be a Banach space or even a Hilbert space. In the latter
case, it is a feature map and there is an associated kernel. The main advantage
of this summary is that it allows one to apply tools from statistics and
machine learning. Furthermore, the mapping from persistence diagrams to
persistence landscapes is stable and invertible. We introduce a weighted
version of the persistence landscape and define a one-parameter family of
Poisson-weighted persistence landscape kernels that may be useful for learning.
We also demonstrate some additional properties of the persistence landscape.
First, the persistence landscape may be viewed as a tropical rational function.
Second, in many cases it is possible to exactly reconstruct all of the
component persistence diagrams from an average persistence landscape. It
follows that the persistence landscape kernel is characteristic for certain
generic empirical measures. Finally, the persistence landscape distance may be
arbitrarily small compared to the interleaving distance.Comment: 18 pages, to appear in the Proceedings of the 2018 Abel Symposiu
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