1,048 research outputs found

    IRAS 13197-1627 has them all: Compton-thin absorption, photo-ionized gas, thermal plasmas, and a broad Fe line

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    We report results from the XMM-Newton observation of IRAS 13197-1627, a luminous IR galaxy with a Seyfert 1.8 nucleus. The hard X-ray spectrum is steep and is absorbed by Compton-thin neutral gas. We detect an Fe emission line at 6.4 keV, consistent with transmission through the absorber. The most striking result of our spectral analysis is the detection of a dominant X-ray reflection component and broad Fe line from the inner accretion disc. The reflection-dominated hard X-ray spectrum is confirmed by the strong Compton hump seen in a previous BeppoSAX observation and could be the sign that most of the primary X-rays are radiated from a compact corona (or e.g. base of the jet) within a few gravitational radii from the black hole. We also detect a relatively strong absorption line at 6.81 keV which, if interpreted as Fe xxv resonant absorption intrinsic to the source, implies an outflow with velocity of about 5000 km/s. In the soft energy band, the high-resolution RGS and the CCD-resolution data show the presence of both photo-ionized gas and thermal plasma emission, the latter being most likely associated with a recent starburst of 15-20 solar masses per year.Comment: accepted for publication in MNRA

    X-ray view of four high-luminosity Swift/BAT AGN: Unveiling obscuration and reflection with Suzaku

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    The Swift/BAT nine-month survey observed 153 AGN, all with ultra-hard X-ray BAT fluxes in excess of 10^-11 erg cm^-2 s^-1 and an average redshift of 0.03. Among them, four of the most luminous BAT AGN (44.73 < Log L(BAT) < 45.31) were selected as targets of Suzaku follow-up observations: J2246.0+3941 (3C 452), J0407.4+0339 (3C 105), J0318.7+6828, and J0918.5+0425. The column density, scattered/reflected emission, the properties of the Fe K line, and a possible variability are fully analyzed. For the latter, the spectral properties from Chandra, XMM-Newton and Swift/XRT public observations were compared with the present Suzaku analysis. Of our sample, 3C 452 is the only certain Compton-thick AGN candidate because of i) the high absorption and strong Compton reflection; ii) the lack of variability; iii) the "buried" nature, i.e. the low scattering fraction (<0.5%) and the extremely low relative [OIII] luminosity. In contrast 3C 105 is not reflection-dominated, despite the comparable column density, X-ray luminosity and radio morphology, but shows a strong long-term variability in flux and scattering fraction, consistent with the soft emission being scattered from a distant region (e.g., the narrow emission line region). The sample presents high (>100) X-to-[OIII] luminosity ratios, confirming the [OIII] luminosity to be affected by residual extinction in presence of mild absorption, especially for "buried" AGN such as 3C 452. Three of our targets are powerful FRII radio galaxies, making them the most luminous and absorbed AGN of the BAT Seyfert survey despite the inversely proportional N_H - L_X relation.Comment: A&A paper in press, 17 page

    A complex idea of human Being : The contribution of neuroscience and ecological social and human approach in the construction of competent and inclusive educational context

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    According to the current lines of contemporary research, the aim of the framework of inclusive education is to respond to the diversity and learning differences of all students, through a different environmental organization for everyone. Brain development is largely a process that depends on experience, in both positive and negative terms (Oliviero, 2017). According to the principle of neuronal plasticity, the brain modifies its structure on the basis of environmental stimuli: in fact, it is environmental and interpersonal experiences that modify our brain structures. In the educational field, it is therefore essential to structure contexts and learning opportunities that generate interest, curiosity, and participation, in heterogeneous environments such as that of today’s school, but respecting the development of each student. The contribution of contemporary neuroscience allows, today, embody the idea of a complex being human. The relationships and the mediators that are used at school, are the signs that students received. That can stimulate the perceptive apparatus and support the development of identity and the relationship between similar (inter-objectivity). In this work we will present, through the perspective of the principles of Universal Design (Rose and Meyer, 2002) how an active, multi-perspective and varied learning, stimulating learning, participation, and a development of soft skills, through the design of educational contexts and using a different methods that enhance diversity

    The X-ray spectra of Compton-thick Seyfert 2 galaxies as seen by BeppoSAX

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    Results from BeppoSAX observations of Compton--thick Seyfert 2 galaxies are summarized and reviewed, and their general properties derived and discussed. In five out of the seven observed sources, the nucleus is directly visible at high X-ray energies, where the photons penetrate absorbers with column densities in the range 1.1-4.3x10^{24} cm-2 (in the other two sources, NGC 1068 and NGC 7674, the nucleus is instead totally obscured at all energies, implying even larger column densities). In most sources there is unambiguous evidence of a reflection component from optically thick, cold matter, while in two (or maybe four) cases there is also evidence of reflection from ionized matter. For the sources with a measured X-ray luminosity, a comparison with the infrared luminosity is made; while in two cases (the Circinus galaxy and NGC 4945) the IR emission appears to be dominated by starburst activity, in the other three sources (NGC 6240, Mrk 3 and TOL 0109-383) it is likely to be dominated by reprocessing of the UV and X-ray photons emitted by an AGN.Comment: Accepted for publication in MNRA
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