5,668 research outputs found
The soft X-ray excess AGN RE J2248-511
We model the spectral energy distribution of the ultrasoft broad-line AGN RE
J2248-511 with Comptonised accretion disc models. These are able to reproduce
the steep optical and ultrasoft X-ray slopes, and the derived black hole mass
is consistent with independent mass estimates. This AGN displays properties of
both broad and narrow line Seyfert 1 galaxies, but we conclude that it is
intrinsically a `normal' Seyfert 1 viewed at high inclination angle.Comment: 4 pages, 1 figure. MG10 Proceeding
Repurposing the (super)crip: media representations of disability at the Rio 2016 Paralympic Games
Mega-events attract ever larger media audiences, and the 2016 Rio Paralympics were no exception. As audiences grow, media coverage extends to ever more varied domains, which are themselves then colonised by an increasing range of discourses. One of main discourses to develop since the early 2000s has been that of the so-called “supercrip”, one which challenges the notion of “impairment” often connected with disability by foregrounding the para-athletes’ triumph over adversity, celebrating instead their courage, grit and perseverance leading to athletic success and personal and increasingly national prestige. In this article we analyse the continuing importance of the supercrip discourse in coverage of the Rio Paralympics, but also move on to highlight its tactical alignment with other – both competing and complementary – discourses of nationalism, sexualisation, militarisation and celebritisation. We analyse textual and visual manifestations of these discourses using both Critical Discourse Analysis and Foucauldian discourse analysis. We conclude by paying particular attention to the increasing visibility of discourses which, while acknowledging the potentially positive role of the supercrip discourse in focussing on athletic success, repurpose that discourse by foregrounding instead the day-to-day experiences of belittling misrepresentation and neglect, including political neglect
Swift captures the spectrally evolving prompt emission of GRB 070616
The origins of Gamma-ray Burst prompt emission are currently not well
understood and in this context long, well-observed events are particularly
important to study. We present the case of GRB 070616, analysing the
exceptionally long-duration multipeaked prompt emission, and later afterglow,
captured by all the instruments on-board Swift and by Suzaku WAM. The high
energy light curve remained generally flat for several hundred seconds before
going into a steep decline. Spectral evolution from hard to soft is clearly
taking place throughout the prompt emission, beginning at 285 s after the
trigger and extending to 1200 s. We track the movement of the spectral peak
energy, whilst observing a softening of the low energy spectral slope. The
steep decline in flux may be caused by a combination of this strong spectral
evolution and the curvature effect. We investigate origins for the spectral
evolution, ruling out a superposition of two power laws and considering instead
an additional component dominant during the late prompt emission. We also
discuss origins for the early optical emission and the physics of the
afterglow. The case of GRB 070616 clearly demonstrates that both broadband
coverage and good time resolution are crucial to pin down the origins of the
complex prompt emission in GRBs.Comment: 13 pages, 11 figures (2 in colour), MNRAS accepte
GRB060602B = Swift J1749.4-2807: an unusual transiently accreting neutron-star X-ray binary
We present an analysis of the Swift BAT and XRT data of GRB060602B, which is
most likely an accreting neutron star in a binary system and not a gamma-ray
burst. Our analysis shows that the BAT burst spectrum is consistent with a
thermonuclear flash (type-I X-ray burst) from the surface of an accreting
neutron star in a binary system. The X-ray binary nature is further confirmed
by the report of a detection of a faint point source at the position of the XRT
counterpart of the burst in archival XMM-Newton data approximately 6 years
before the burst and in more recent XMM-Newton data obtained at the end of
September 2006 (nearly 4 months after the burst). Since the source is very
likely not a gamma-ray burst, we rename the source Swift J1749.4-2807, based on
the Swift/BAT discovery coordinates. Using the BAT data of the type-I X-ray
burst we determined that the source is at most at a distance of 6.7+-1.3 kpc.
For a transiently accreting X-ray binary its soft X-ray behaviour is atypical:
its 2-10 keV X-ray luminosity (as measured using the Swift/XRT data) decreased
by nearly 3 orders of magnitude in about 1 day, much faster than what is
usually seen for X-ray transients. If the earlier phases of the outburst also
evolved this rapidly, then many similar systems might remain undiscovered
because the X-rays are difficult to detect and the type-I X-ray bursts might be
missed by all sky surveying instruments. This source might be part of a class
of very-fast transient low-mass X-ray binary systems of which there may be a
significant population in our Galaxy.Comment: Accepted for publication in MNRA
Multiwavelength XMM-Newton observations of the Laor et al. sample of PG quasars
We present XMM-Newton/EPIC spectra for the Laor et al. sample of Palomar
Green quasars. We find that a power-law provides a reasonable fit to the 2-5
keV region of the spectra. Excess soft X-ray emission below 2 keV is present
for all objects, with the exception of those known to contain a warm absorber.
A single power-law is, however, a poor fit to the 0.3-10.0 keV spectrum and
instead we find that a simple model, consisting of a broken power-law (plus an
iron line), provides a reasonable fit in most cases. The equivalent width of
the emission line is constrained in just twelve objects but with low (<2 sigma)
significance in most cases. For the sources whose spectra are well-fit by the
broken power-law model, we find that various optical and X-ray line and
continuum parameters are well-correlated; in particular, the power-law photon
index is well-correlated with the FWHM of the Hbeta line and the photon indices
of the low and high energy components of the broken power-law are
well-correlated with each other. These results suggest that the 0.3-10 keV
X-ray emission shares a common (presumably non-thermal) origin, as opposed to
suggestions that the soft excess is directly produced by thermal disc emission
or via an additional spectral component. We present XMM-Newton/OM data which we
combine with the X-ray spectra so as to produce broad-band spectral energy
distributions, free from uncertainties due to long-term variability in
non-simultaneous data. Fitting these optical-UV spectra with a Comptonized disc
model indicates that the soft X-ray excess is independent of the accretion
disc, confirming our interpretation of the tight correlation between the hard
and soft X-ray spectra.Comment: Accepted for publication in MNRA
Gas and dust properties in the afterglow spectra of GRB 050730
We present early WHT ISIS optical spectroscopy of the afterglow of gamma-ray
burst GRB 050730. The spectrum shows a DLA system with the highest measured
hydrogen column to date: N(HI) = 22.1 +/- 0.1 at the third-highest GRB redshift
z = 3.968. Our analysis of the Swift XRT X-ray observations of the early
afterglow show X-ray flares accompanied by decreasing X-ray absorption. From
both the optical and the X-ray spectra we constrain the dust and gas properties
of the host galaxy. We find the host to be a low metallicity galaxy, with low
dust content. Much of the X-ray absorbing gas is situated close to the GRB,
whilst the HI absorption causing the DLA is most likely located further out.Comment: 5 pages, 2 figures. Accepted for A&A Letter
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Questionnaire study to gain an insight into the manufacturing and fitting process of artificial eyes in children: an ocularist perspective
Purpose
To gain an insight into the manufacturing and fitting of artificial eyes in children and potential improvements to the process.
Method
An online qualitative survey was distributed to 39 ocularists/prosthetists in Europe and Canada. Participants were recruited through purposive sampling, specifically maximum variation sampling from the researcher’s contacts and an online search.
Results
The findings highlighted the current impression technique as being the most difficult yet most important part of the current process for both the ocularist and child patient. Negatively affecting obtaining a good impression, the child patients distress can be reduced by their parents by providing encouragement, reassurance, practicing the insertion and removal of the artificial eye and being matter of fact. Whilst improvements to the current process provided mixed views, the incorporation of current technology was perceived as not being able to meet the requirements to produce aesthetically pleasing artificial eyes.
Conclusion
The current artificial eye process can be seen as an interaction with its success being dependent on the child patient’s acceptance and adjustment which is dependent on the factors associated to the process. Investigation into the needs of the patient and whether technology can improve the process are the next steps in its advancement
Gamma-Ray Burst Afterglows as Probes of Environment and Blastwave Physics II: The Distribution of p and Structure of the Circumburst Medium
We constrain blastwave parameters and the circumburst media of a subsample of BeppoSAX Gamma-Ray Bursts. For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical and nIR afterglow data. The spectral fits have been done in count space and include the effects of metallicity, and are compared with the previously reported optical and X-ray temporal behaviour. Assuming the fireball model, we can find a mean value of p for the sample as a whole of 2.035. A statistical analysis Of the distribution demonstrates that the p values in this sample are inconsistent with a single universal value for p at the 3sigma level or greater. This approach provides us with a measured distribution of circumburst density structures rather than considering only the cases of k = 0 (homogeneous) and k = 2 (wind-like). We find five GRBs for which k can be well constrained, and in four of these cases the circumburst medium is clearly wind-like. The fifth source has a value of 0 less than or equal to k less than or equal to 1, consistent with a homogeneous circumburst medium
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