Abstract
We present a detailed multiwavelength study of an unobscured, highly super-Eddington Type-1 QSO RX J0439.6-5311. We combine the latest XMM–Newton observation with all archival data from ...infrared to hard X-rays. The optical spectrum is very similar to that of 1H 0707-495 in having extremely weak O iii and strong Fe ii emission lines, although the black hole mass is probably slightly higher at 5-10 × 106 M⊙. The broad-band spectral energy distribution is uniquely well defined due to the extremely low Galactic and intrinsic absorption, so the bolometric luminosity is tightly constrained. The optical/UV accretion disc continuum is seen down to 900 Å, showing that there is a standard thin disc structure down to R ≥ 190–380 R
g and determining the mass accretion rate through the outer disc. This predicts a much higher bolometric luminosity than observed, indicating that there must be strong wind and/or advective energy losses from the inner disc, as expected for a highly super-Eddington accretion flow. Significant outflows are detected in both the narrow-line region (NLR) and broad-line region (BLR) emission lines, confirming the presence of a wind. We propose a global picture for the structure of a super-Eddington accretion flow where the inner disc puffs up, shielding much of the potential NLR material, and show how inclination angle with respect to this and the wind can explain very different X-ray properties of RX J0439.6-5311 and 1H 0707-495. Therefore, this source provides strong supporting evidence that ‘simple’ and ‘complex’ super-Eddington NLS1s can be unified within the same accretion flow scenario but with different inclination angles. We also propose that these extreme NLS1s could be the low-redshift analogues of weak emission-line quasars.
Abstract
In this third paper in a series of three, we present a detailed study of the broad-band spectral energy distribution (SED) of active galactic nuclei (AGNs) based on a nearby unobscured type ...1 AGN sample. We perform a systematic cross-correlation study of several key parameters, i.e. Γ2-10 keV, L
2-10 keV, L
bol/L
Edd = λEdd, L
bol/L
2-10 keV = κ2-10 keV, , FWHMHβ, M
BH, αox, αX and αUV. The well-defined spectral properties of the sample enable us to improve existing relations and to identify new correlations among these parameters. We confirm a break region around FWHMHβ ≃ 4000 km s−1 in the Γ2-10 keV versus FWHMHβ correlation and log(M
BH) ≃ 8.0 in the Γ2-10 keV versus M
BH correlation, where these correlations appear to change form. Beyond the break point, the intrinsic Γ2-10 keV index is dispersed around 1.8. Several new correlations are also reported in this paper, e.g. strong correlations in κ5100 versus λEdd, κ5100 versus κ2-10 keV and κ2-10 keV versus M
BH. The principal component analysis (PCA) is performed on the correlation matrix of the above parameters. This shows that the three physical parameters, i.e. black hole mass, mass accretion rate and Eddington ratio, drive the majority of the correlations. This is consistent with PCA results found from previous optical spectral studies.
For each key parameter, we split the AGNs into three subsamples, binned based on increasing value of that parameter. We co-add the model SEDs for each object in the subsample to see how the SED changes with that parameter. Most parameters, except L
bol, show similar systematic changes in the SED such that the temperature at which the disc peaks is correlated with the ratio of power in the disc versus the Comptonized components and the hard X-ray spectral index. This underlying change in SED shape shows that AGNs do exhibit intrinsically different spectral states. This is superficially similar to the SED differences in black hole binary (BHB) seen as λEdd increases, but the analogy does not hold in detail. Only objects with the highest λEdd appear to correspond to a BHB spectral state (the disc-dominated high/soft state). The AGNs with typical mass accretion rates have spectra which do not match well with any state observed in BHB. We speculate that this could be due to the presence of a powerful ultraviolet line-driven disc wind, which complicates simple mass scaling between stellar and supermassive black holes.
Overdiagnosis and child health Ward Platt, Martin
Archives of disease in childhood,
10/2018, Letnik:
103, Številka:
10
Journal Article
Recenzirano
Black and Welch published their landmark paper on the overestimation of disease prevalence 25 years ago, and even then they saw the problem as having crept up over the previous two decades.6 For ...fairly obvious reasons the issue has been of particular concern to radiologists as techniques and modalities have become progressively more refined, so more things are found on imaging that are not necessarily diseases.7 We can think of overdiagnosis as part of a spectrum of ‘Too Much Medicine’ that includes over-referral, overinvestigation, the invention of disease entities and ‘treatments’ for them and either mistaking pathology for physiology or becoming intolerant of the extremes of physiological variability. In spite of the measured tone of the guideline document itself, strict application of the recommendations as currently framed seems to result in excessive resort to phototherapy, extended hospital stays and multiple heel prick bilirubin measurements in a significant number of babies who previously would have avoided much of this. Imagine two practices that are used in a particular condition: let’s call one ‘standard’ and the other ‘variant’, and let’s say that neither has been tested against the other to assess effectiveness or harm. ...for the sake of argument, let’s assume that the ‘variant’ practice will one day be found to be better, because it turns out to be less harmful though no more effective.
Validation for Dr Apgar’s score Ward Platt, Martin
Archives of disease in childhood,
01/2019, Letnik:
104, Številka:
1
Journal Article
Recenzirano
The third is that she published her work in a paediatric journal, when in fact she published it in the now defunct ‘Current Researches in Anesthesia and Analgesia’ (full text reproduced in the online ...supplementary appendix).1 SP110.1136/archdischild-2018-315176.supp1 Supplementary file 1 Setting the record straight is one thing, but there are many other remarkable features about Dr Apgar’s life and career which are just as interesting. Persson et al related the Apgar scores at 5 and 10 min in term babies to the subsequent development of epilepsy and cerebral palsy in childhood in a cohort of 1.2 million Swedish children, demonstrating a gradient of rates of neurological morbidity in relation to each increment of the overall score. Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
The ways in which trainees become involved with the child and the family, before and after the death, are necessarily different in each context. Since these various modes of death affect the ...attending staff in different ways, there can be no single approach to fit all circumstances. The finding that staff can be deeply affected by the death of a child is supported by a recent paper from Canada in which Plante and Cyr measured levels of short-term grief and long-term grief in relation to child death across a variety of professionals and levels of experience.2 Importantly, they found that ‘Being comfortable caring for a dying patient’ was strongly associated with a lower intensity of grief. ...Bateman et al described a particular form of structured group debriefing which they called the ‘Wrap-up’, which was positively received by paediatric residents; but the evaluation relied on questionnaire feedback and was further limited by not attempting any specific measure of psychological state.6 As noted above, child death review meetings have to take place, and it would be useful to know the extent to which these are helpful or harmful psychologically for the junior participants.
ABSTRACT
We use the SOUX sample of ∼700 active galactic nucleus (AGN) to form average optical-ultraviolet (UV)-X-rays spectral energy distributions (SEDs) on a two-dimensional (2D) grid of MBH and ...L2500. We compare these with the predictions of a new AGN SED model, qsosed, which includes prescriptions for both hot and warm Comptonization regions as well as an outer standard disc. This predicts the overall SED fairly well for 7.5 < log(MBH/M⊙) < 9.0 over a wide range in L/LEdd, but at higher masses the outer disc spectra in the model are far too cool to match the data. We create optical-UV composites from the entire Sloan Digital Sky Survey sample and use these to show that the mismatch is due to there being no significant change in spectral shape of the optical-UV continuum across several decades of MBH at constant luminosity. We show for the first time that this cannot be matched by standard disc models with high black hole spin. These apparently fit, but are not self-consistent as they do not include the General Relativistic effects for the emission to reach the observer. At high spin, increased gravitational redshift compensates for almost all of the higher temperature emission from the smaller inner disc radii. The data do not match the predictions made by any current accretion flow model. Either the disc is completely covered by a warm Comptonization layer whose properties change systematically with L/LEdd, or the accretion flow structure is fundamentally different to that of the standard disc models.
ABSTRACT
We present the first intensive study of the variability of the near-infrared coronal lines in an active galactic nucleus (AGN). We use data from a 1-yr-long spectroscopic monitoring campaign ...with roughly weekly cadence on NGC 5548 to study the variability in both emission line fluxes and profile shapes. We find that in common with many AGN coronal lines, those studied here are both broader than the low-ionizaton forbidden lines and blueshifted relative to them, with a stratification that implies an origin in an outflow interior to the standard narrow line region. We observe for the first time S viii and Si vi coronal line profiles that exhibit broad wings in addition to narrow cores, features not seen in either S ix or Si x. These wings are highly variable, whereas the cores show negligible changes. The differences in both the profile shapes and variability properties of the different line components indicate that there are at least two coronal line regions in AGN. We associate the variable, broad wings with the base of an X-ray heated wind evaporated from the inner edge of the dusty torus. The coronal line cores may be formed at several locations interior to the narrow line region: either along this accelerating, clumpy wind or in the much more compact outflow identified with the obscurer and so emerging on scales similar to the outer accretion disc and broad-line region.
An experimental study of the effects of the sodium salt of poly(methacrylic acid) (Na-PMAA) on non-photochemical laser-induced nucleation (NPLIN) of sodium acetate crystals is presented. Seeding of ...supersaturated aqueous solutions with anhydrous (AH) seeds always produced trihydrate (TH) crystals, with or without polymer additive. Using NPLIN, with no Na-PMAA and at low Na-PMAA concentrations (0.25% w/w) AH sodium acetate was produced, firstly as plate-like form IV, but subsequently growing needles, likely to be form I. At high Na-PMAA concentrations (0.73% w/w) we observe formation mostly of stable bubbles. In all samples at low laser peak power densities (<26 MW cm
−2
) we show for the first time using NPLIN that both crystals and bubbles can be nucleated with a single laser pulse. Measurements of the dependence of bubble or crystal count on laser pulse power indicate a common mechanistic origin for nucleation, which is cavitation due to laser heating of impurity nanoparticles. The bubbles observed are attributed to laser heating of the nanoparticles to high temperatures, resulting in gas formed by thermochemical reactions or gas that was previously dissolved in the solution. Our results provide new insight into the particle-heating mechanism for NPLIN, but whether stable bubbles play a defining role in the nucleation of crystals remains to be resolved.
Laser pulse nucleates anhydrous sodium acetate and stable gas bubbles from solution.
We explore the origin of the strong soft X-ray excess in narrow-line Seyfert 1 galaxies using spectral-timing information from a 120 ks XMM-Newton observation of PG 1244+026. Spectral fitting alone ...cannot distinguish between a true additional soft X-ray continuum component and strongly relativistically smeared reflection, but both models also require a separate soft blackbody component. This is most likely intrinsic emission from the disc extending into the lowest energy X-ray bandpass. The rms spectra on short time-scales (200-5000 s) contain both (non-disc) soft excess and power-law emission. However, the spectrum of the variability on these time-scales correlated with the 4-10 keV light curve contains only the power law. Together these show that there is fast variability of the soft excess which is independent of the 4-10 keV variability. This is inconsistent with a single reflection component making the soft X-ray excess as this necessarily produces correlated variability in the 4-10 keV bandpass. Instead, the rms and covariance spectra are consistent with an additional cool Comptonization component which does not contribute to the spectrum above 2 keV. PUBLICATION ABSTRACT
Abstract
We assemble a sample of 696 type 1 active galactic nuclei (AGN) up to a redshift of z = 2.5, all of which have an SDSS spectrum containing at least one broad emission line (H α, H β, or Mg ...ii) and an XMM-Newton X-ray spectrum containing at least 250 counts in addition to simultaneous optical/ultraviolet photometry from the XMM Optical Monitor. Our sample includes quasars and narrow-line Seyfert 1s: thus our AGN span a wide range in luminosity, black hole mass, and accretion rate. We determine single-epoch black hole mass relations for the three emission lines and find that they provide broadly consistent mass estimates whether the continuum or emission line luminosity is used as the proxy for the broad emission line region radius. We explore variations of the UV/X-ray energy index αox with the UV continuum luminosity and with black hole mass and accretion rate, and make comparisons to the physical quasar spectral energy distribution model qsosed. The majority of the AGN in our sample lie in a region of parameter space with 0.02 < L/LEdd < 2 as defined by this model, with narrow-line type 1 AGN offset to lower masses and higher accretion rates than typical broad-line quasars. We find differences in the dependence of αox on UV luminosity between both narrow/broad-line and radio-loud/quiet subsets of AGN: αox has a slightly weaker dependence on UV luminosity for broad-line AGN and radio-loud AGN have systematically harder αox.
PDF
