Dust reverberation mapping in the era of big optical surveys and its cosmological application

The time lag between optical and near-infrared (IR) flux variability can be taken as a means to determine the sublimation radius of the dusty "torus" around supermassive black holes in active galactic nuclei (AGN). I will show that data from big optical survey telescopes, e.g. the Large Synoptic Survey Telescope (LSST), can be used to measure dust sublimation radii as well. The method makes use of the fact that the Wien tail of the hot dust emission reaches into the optical and can be reliably recovered with high-quality photometry. Simulations show that dust sublimation radii for a large sample of AGN can be reliably established out to redshift z ~ 0.1-0.2 with the LSST. Owing to the ubiquitous presence of AGN up to high redshifts, they have been studies as cosmological probes. Here, I discuss how optically-determined dust time lags fit into the suggestion of using the dust sublimation radius as a "standard candle" and propose and extension of the dust time lags as "standard rulers" in combination with IR interferometry.Comment: 6 pages, 4 figures, 1 table; accepted by ApJL (Feb 18, 2014

The dust sublimation radius as an outer envelope to the bulk of the narrow Fe Kalpha line emission in Type 1 AGN

The Fe Kalpha emission line is the most ubiquitous feature in the X-ray spectra of active galactic nuclei (AGN), but the origin of its narrow core remains uncertain. Here, we investigate the connection between the sizes of the Fe core emission regions and the measured sizes of the dusty tori in 13 local Type 1 AGN. The observed Fe K emission radii (R_fe) are determined from spectrally resolved line widths in X-ray grating spectra, and the dust sublimation radii (R_dust) are measured either from optical/near-infrared reverberation time lags or from resolved near-infrared interferometric data. This direct comparison shows, on an object-by-object basis, that the dust sublimation radius forms an outer envelope to the bulk of the Fe K emission. R_fe matches R_dust well in the AGN with the best constrained line widths currently. In a significant fraction of objects without a clear narrow line core, R_fe is similar to, or smaller than the radius of the optical broad line region. These facts place important constraints on the torus geometries for our sample. Extended tori in which the solid angle of fluorescing gas peaks at well beyond the dust sublimation radius can be ruled out. We also test for luminosity scalings of R_fe, finding that Eddington ratio is not a prime driver in determining the line location in our sample. We discuss in detail potential caveats due to data analysis and instrumental limitations, simplistic line modeling, uncertain black hole masses, as well as sample selection, showing that none of these is likely to bias our core result. The calorimeter on board Astro-H will soon vastly increase the parameter space over which line measurements can be made, overcoming many of these limitations.Comment: ApJ in press. Community comments greatly appreciated. 13 pages, 4 figures and 2 tables including an appendi

Radiative Transfer Modeling of Three-Dimensional Clumpy AGN Tori and its Application to NGC 1068

Recent observations of NGC 1068 and other AGN support the idea of a geometrically and optically thick dust torus surrounding the central supermassive black hole and accretion disk of AGN. In type 2 AGN, the torus is seen roughly edge-on, leading to obscuration of the central radiation source and a silicate absorption feature near 10 micron. While most of the current torus models distribute the dust smoothly, there is growing evidence that the dust must be arranged in clouds. We describe a new method for modeling near- and mid-infrared emission of 3-dimensional clumpy tori using Monte Carlo simulations. We calculate the radiation fields of individual clouds at various distances from the AGN and distribute these clouds within the torus region. The properties of the individual clouds and their distribution within the torus are determined from a theoretical approach of self-gravitating clouds close to the shear limit in a gravitational potential. We demonstrate that clumpiness in AGN tori can overcome the problem of over-pronounced silicate features. Finally, we present model calculations for the prototypical Seyfert 2 galaxy NGC 1068 and compare them to recent high-resolution measurements. Our model is able to reproduce both the SED and the interferometric observations of NGC 1068 in the near- and mid-infrared.Comment: 16 pages, 16 figures, 6 tables (figures reduced due to astro-ph limitations); accepted by A&

The subarcsecond mid-infrared view of local active galactic nuclei: II. The mid-infrared--X-ray correlation

We present an updated mid-infrared (MIR) versus X-ray correlation for the local active galactic nuclei (AGN) population based on the high angular resolution 12 and 18um continuum fluxes from the AGN subarcsecond MIR atlas and 2-10 keV and 14-195 keV data collected from the literature. We isolate a sample of 152 objects with reliable AGN nature and multi-epoch X-ray data and minimal MIR contribution from star formation. Although the sample is not homogeneous or complete, we show that our results are unlikely to be affected by biases. The MIR--X-ray correlation is nearly linear and within a factor of two independent of the AGN type and the wavebands used. The observed scatter is <0.4 dex. A possible flattening of the correlation slope at the highest luminosities probed (~ 10^45 erg/s) is indicated but not significant. Unobscured objects have, on average, an MIR--X-ray ratio that is only <= 0.15 dex higher than that of obscured objects. Objects with intermediate X-ray column densities (22 < log N_H < 23) actually show the highest MIR--X-ray ratio on average. Radio-loud objects show a higher mean MIR--X-ray ratio at low luminosities, while the ratio is lower than average at high luminosities. This may be explained by synchrotron emission from the jet contributing to the MIR at low-luminosities and additional X-ray emission at high luminosities. True Seyfert 2 candidates and double AGN do not show any deviation from the general behaviour. Finally, we show that the MIR--X-ray correlation can be used to verify the AGN nature of uncertain objects. Specifically, we give equations that allow to determine the intrinsic 2-10 keV luminosities and column densities for objects with complex X-ray properties to within 0.34 dex. These techniques are applied to the uncertain objects of the remaining AGN MIR atlas, demonstrating the usefulness of the MIR--X-ray correlation as an empirical tool.Comment: Accepted for publication in MNRAS, 40 pages, 25 figure

Measurement of interleukin 1 alpha and 1 beta (IL-1 alpha and IL-1 beta) in human cystic lésions of the jaw. Implications for the pathogenesis of radicular cysts

Human radicular cystic tissue of jaws was found to contain between 0.823 pg/mg to 18.026 pg/mg interleukin 1 beta and from 0.34 pg/mg to 0.708 pg/mg interleukin 1 alpha.No IL-1 beta and alpha could be found in specimens from healthy patients. A finding which may be extremely relevant in cystic growth and episodes of alveolar bone resorption around the cystic lesion.Human radicular cystic tissue of jaws was found to contain between 0.823 pg/mg to 18.026 pg/mg interleukin 1 beta and from 0.34 pg/mg to 0.708 pg/mg interleukin 1 alpha.No IL-1 beta and alpha could be found in specimens from healthy patients. A finding which may be extremely relevant in cystic growth and episodes of alveolar bone resorption around the cystic lesion.Les tissus des kystes radiculaires chez l’homme contiennent 0,823 à 18,026 pg/mg d’interleukines 1 beta et 0,34 à 0,708 pg/mg d’interleukines alpha. Il n’a pas été trouvé d’IL-1 beta et alpha dans des prélèvements effectués chez des individus sains. Cette constatation peut avoir des conséquences importantes en relation avec la croissance du kyste et la résorption de l’os alvéolaire avoisinant

COVID-19–related skin manifestations: Update on therapy

An increasing body of evidence has been produced in a very limited period to improve the understanding of skin involvement in the current coronavirus 2019 disease pandemic, and how this novel disease affects the management of dermatologic patients. A little explored area is represented by the therapeutic approach adopted for the different skin manifestations associated with the infection. An overview of the current scenario is provided, through review of the English-language literature published until October 30, 2020, and comparison with the personal experience of the authors. As dermatologists, our primary aim is to support patients with the highest standard of care and relieve suffering, even with lesions not life-threatening. With asymptomatic COVID-19 patients, patient discomfort related to skin lesions should not be undervalued and intervention to accelerate healing should be provided. Consensus protocols are warranted to assess the best skin-targeted treatments in COVID-19 patients

Estimating age composition for multiple years when there are gaps in the ageing data: the case of western Atlantic bluefin tuna

Age–length key (ALK) methods generally perform well when length samples and age samples are representative of the underlying population. It is unclear how well these methods perform when lengths are representative but age samples are sparse (i.e. age samples are small or missing in many years, and some length groups do not have any age observations). With western Atlantic bluefin tuna, the available age data are sparse and have been, for the most part, collected opportunistically. We evaluated two methods capable of accommodating sparse age data: a novel hybrid ALK (combining forward ALKs and cohort slicing) and the combined forward-inverse ALK. Our goal was to determine if the methods performed better than cohort slicing, which has traditionally been used to obtain catch-at-age for Atlantic bluefin tuna, given the data limitations outlined above. Simulation results indicated that the combined forward-inverse ALK performed much better than the other methods. When applied to western Atlantic bluefin tuna data, the combined forward-inverse ALK approach was able to track cohorts and identified an inconsistency in the ageing of some samples