180 research outputs found

    The Dusty Tori of Nearby QSOs as Constrained by High-Resolution Mid-IR Observations

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    We present mid-infrared (MIR; 7.5–13.5 μm) imaging and spectroscopy observations obtained with the CanariCam (CC) instrument on the 10.4-m Gran Telescopio CANARIAS for a sample of 20 nearby, MIR bright and X-ray luminous quasi-stellar objects (QSOs). We find that for the majority of QSOs the MIR emission is unresolved at angular scales ∼0.3 arcsec, corresponding to physical scales ≲ 600 pc. We find that the higher-spatial resolution CC spectra have similar shapes to those obtained with Spitzer/IRS, and hence we can assume that the spectra are not heavily contaminated by extended emission in the host galaxy. We thus take advantage of the higher signal-to-noise ratio Spitzer/IRS spectra, as a fair representation of the nuclear emission, to decompose it into a combination of active galactic nuclei (AGN), polycyclic aromatic hydrocarbon (PAH) and stellar components. In most cases, the AGN is the dominant component, with a median contribution of 85 per cent of the continuum light at MIR (5–15 μm) within the IRS slit. This IR AGN emission is well reproduced by clumpy torus models. We find evidence for significant differences in the parameters that describe the dusty tori of QSOs when compared with the same parameters of Seyfert 1 and 2 nuclei. In particular, we find a lower number of clouds (N0 ≲ 12), steeper radial distribution of clouds (q ∼ 1.5–3.0) and clouds that are less optically thick (τV ≲ 100) than in Seyfert 1, which could be attributed to dusty structures that have been partially evaporated and piled up by the higher radiation field in QSOs. We find that the combination of the angular width σtorus, viewing angle i, and number of clouds along the equatorial line, N0, produces large escape probabilities (Pesc \u3e 2 per cent) and low geometrical covering factors (f2 ≲ 0.6), as expected for AGN with broad lines in their optical spectra

    Efecto de la triploidía sobre los parámetros musculares y nutricionales del rodaballo (Scophthalmus maximus, L.) después de su maduración sexual

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    Con el objetivo de una mejor comprensión de la calidad final del rodaballo triploide (Scophtha/mus maximus, L.), la celularidad musculary los parámetros de calidad de la carne fueron estudiados en 7 rodaballos diploides y 7 lriploides de 33 meses de edad, todos ejemplares decultivoy de un tamaño similar. La celularidad del músculo blanco se evaluó por medio del número y diámetro de las fibras musculares. Para determinarla calidad de la carne fueron analizados diversos parámetros físico-químicos (humedad, proteína, grasa y ácidos grasas totales) y se determinaIOO las propiedades mecánicas de la lextura (dureza, elasticidad, masticabilidad, cohe~ividad y gomosidad) con un texturómetro. El mecanismode crecimiento muscular difirió entre los dos grupos, de tal manera que el tamaño de las fibras fue mayor (p<O,OOI)en los triploides , mientrasquela densidad de fibras musculares fue mayor en el grupo de los diploides, lo que demuestra que las diferencias genéticas produjeron dtlerente celularidad muscular en ambos grupos. No se encontraron diferencias significativas en las propiedades texturales ni en los parámetros decalidad de la carne entre diploides y triploides.In order lo a beller understanding of Ihe final qualily of lriploid turbot (Scophthalmus maximus, L.), muscle cellularily and qualily parametersoflhe flesh were studied on 7 diploid and 7 triploid 33 months old farmed turbot of similar size. White muscle cellularily was evaluated by meansofIhe number and diameter of muscle fibers. lo ascertain the flesh qualily, several physlco-cbemlcal parameters (moisture, protein, total fat andfalty acids) were analyzed, and textural mechanical properties (hardness, springiness, chewiness, cohesiveness, gumminess) were determinedwitha texturometer. Muscle growth mechanism differed between both groups, such that muscie fibres size was greater (p<O,OOI)in triploid specimens, wihereas muscle fibre density was higher in diploid group, thus showing mat genetic differences produced different muscie cellularity in bothgroups. No significant differences were found in textural properties and flesh qualily parameters between diploid and triploid groups

    The Galaxy Activity, Torus, and Outflow Survey (GATOS): III. Revealing the inner icy structure in local active galactic nuclei

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    We use JWST/MIRI MRS spectroscopy of a sample of six local obscured type 1.9/2 active galactic nuclei (AGN) to compare their nuclear mid-IR absorption bands with the level of nuclear obscuration traced by X-rays. This study is the first to use subarcsecond angular resolution data of local obscured AGN to investigate the nuclear mid-IR absorption bands with a wide wavelength coverage (4.9–28.1 μm). All the nuclei show the 9.7 μm silicate band in absorption. We compare the strength of the 9.7 and 18 μm silicate features with torus model predictions. The observed silicate features are generally well explained by clumpy and smooth torus models. We report the detection of the 6 μm dirty water ice band (i.e., a mix of water and other molecules such as CO and CO2) at subarcsecond scales (∼0.26″ at 6 μm; inner ∼50 pc) in a sample of local AGN with different levels of nuclear obscuration in the range log NHX-Ray (cm−2)∼22 − 25. We find good correlation between the 6 μm water ice optical depths and NHX-Ray. This result indicates that the water ice absorption might be a reliable tracer of the nuclear intrinsic obscuration in AGN. The weak water ice absorption in less obscured AGN (log NHX-ray (cm−2)≲23.0 cm−2) might be related to the hotter dust temperature (> TsubH2O ∼ 110 K) expected to be reached in the outer layers of the torus due to their more inhomogeneous medium. Our results suggest it might be necessary to include the molecular content, such as H2O, aliphatic hydrocarbons (CH−), and more complex polycyclic aromatic hydrocarbon (PAH) molecules, in torus models to better constrain key parameters such as the torus covering factor (i.e., nuclear obscuration)

    Tratamento biológico do líquido da casca do coco verde.

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    Deconvolution of JWST/MIRI Images: Applications to an Active Galactic Nucleus Model and GATOS Observations of NGC 5728

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    The superb image quality, stability, and sensitivity of JWST permit deconvolution techniques to be pursued with a fidelity unavailable to ground-based observations. We present an assessment of several deconvolution approaches to improve image quality and mitigate the effects of the complex JWST point-spread function (PSF). The optimal deconvolution method is determined by using WebbPSF to simulate JWST’s complex PSF and MIRISim to simulate multiband JWST/Mid-Infrared Imager Module (MIRIM) observations of a toy model of an active galactic nucleus (AGN). Five different deconvolution algorithms are tested: (1) Kraken deconvolution, (2) Richardson–Lucy, (3) the adaptive imaging deconvolution algorithm, (4) sparse regularization with the Condat–Vũ algorithm, and (5) iterative Wiener filtering and thresholding. We find that Kraken affords the greatest FWHM reduction of the nuclear source of our MIRISim observations for the toy AGN model while retaining good photometric integrity across all simulated wave bands. Applying Kraken to Galactic Activity, Torus, and Outflow Survey (GATOS) multiband JWST/MIRIM observations of the Seyfert 2 galaxy NGC 5728, we find that the algorithm reduces the FWHM of the nuclear source by a factor of 1.6–2.2 across all five filters. Kraken images facilitate detection of extended nuclear emission ∼2.″5 (∼470 pc, position angle ≃ 115°) in the SE–NW direction, especially at the longest wavelengths. We demonstrate that Kraken is a powerful tool to enhance faint features otherwise hidden in the complex JWST PSF
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