Examinando por Autor "Middei, R."

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Acceso Abierto
A broadband X-ray view of the NLSy1 1E 0754.6+3928
(EDP Sciences, 2020-02-28) Middei, R.; Tombesi, F.; Vagnetti, F.; Serafinelli, R.; Bianchi, S.; Miniutti, G.; Marinucci, A.; Matzeu, G. A.; Petrucci, P. O.; Ursini, F.; Zaino, A.; Agenzia Spaziale Italiana (ASI); Istituto Nazionale Astrofisica (INAF); European Space Agency (ESA); 0000-0001-9815-9092; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The soft X-ray band of many active galactic nuclei (AGNs) is affected by obscuration due to partially ionised matter crossing our line of sight. In this context, two past XMM-Newton observations that were six months apart and a simultaneous NuSTAR-Swift exposure of the Narrow Line Seyfert 1 galaxy 1E 0754.6+3928, which was approximately eight years later, revealed an intense and variable warm absorber (WA) and hints of additional absorbers in the Fe K alpha band.Aims. We aim to provide the first X-ray characterisation of this AGN by discussing its broadband (0.3-79 keV) spectrum and temporal properties.Methods. We conduct a temporal and spectroscopic analysis on two similar to 10 ks (net exposure) XMM-Newton snapshots performed in April and October 2006. We also study the high energy behaviour of 1E 0754.6+3928 and model its broadband spectrum by using simultaneous Swift-NuSTAR data. Both phenomenological and physically motivated models are tested.Results. We find the presence of flux variability of similar to 150% and 30% for 0.3-2 and 2-10 keV bands, respectively, and spectral changes at months timescales of Delta Gamma similar to 0.4. A reflection component that is consistent with being constant over years and arising from relatively cold material that is far from the central super massive black hole is detected. The main spectral feature shaping the 1E 0754.6+3928 spectrum is a WA. Such a component is persistent over the years and the variability of its ionisation and column density is observed down on months in the ranges 3x10(22)cm(-2)less than or similar to N-H less than or similar to 7.2x10(22)cm(-2) and 1.5 less than or similar to log (xi/erg s(-1) cm) less than or similar to 2.1. Despite the short exposures, we find possible evidence of two additional high-ionisation and high-velocity outflow components in absorption.Conclusions. Our analysis suggests the existence of a complex system of absorbers in 1E 0754.6+3928. Longer exposures are required in order to characterise, on more solid grounds, the absorbers in this AGN.
Acceso Abierto
The first broad-band X-ray view of the narrow-line Seyfert 1 Ton S180
(Oxford Academics: Oxford University Press, 2020-07-15) Matzeu, G. A.; Nardini, E.; Parker, M. L.; Reeves, J. N.; Braito, V.; Porquet, D.; Middei, R.; Kammoun, E.; Lusso, E.; Alston, W. N.; Giustini, M.; Lobban, A. P.; Joyce, A. M.; Igo, Z.; Ebrero, J.; Ballo, L.; Santos Lleó, M.; Schartel, N.; European Research Council (ERC); European Commission (EC); Agenzia Spaziale Italiana (ASI); Istituto Nazionale di Astrofisica (INAF); Comunidad de Madrid; National Aeronautics and Space Administration (NASA); Giustini, M. [0000-0002-1329-658X]; Kammoun, E. [0000-0002-0273-218X]; Braito, V. [0000-0002-2629-4989]; Matzeu, G. [0000-0003-1994-5322]; Parker, M. [0000-0002-8466-7317]; Lobban, A. [0000-0002-6433-1357]; Santos Lleo, M. [0000-0001-5948-8360]; Middei, R. [0000-0001-9815-9092]; Igo, Z. [0000-0001-9274-1145]; Alston, W. [0000-0003-2658-6559]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We present joint XMM-Newton and NuSTAR observations of the 'bare' narrow-line Seyfert 1 Ton S180 (z = 0.062), carried out in 2016 and providing the first hardX-ray view of this luminous galaxy. We find that the 0.4-30 keV band cannot be self-consistently reproduced by relativistic reflection models, which fail to account simultaneously for the soft and hard X-ray emission. The smooth soft excess prefers extreme blurring parameters, confirmed by the nearly featureless nature of the Reflection Grating Spectrometer (RGS) spectrum, while the moderately broad Fe K line and the modest hard excess above 10 keV appear to arise in a milder gravity regime. By allowing a different origin of the soft excess, the broad-band X-ray spectrum and overall spectral energy distribution (SED) are well explained by a combination of (a) direct thermal emission from the accretion disc, dominating from the optical to the far/extreme UV; (b) Comptonization of seed disc photons by a warm (kT(e) similar to 0.3 keV) and optically thick (tau similar to 10) corona, mostly contributing to the soft X-rays; (c) Comptonization by a standard hot (kT(e) greater than or similar to 100 keV) and optically thin (tau < 0.5) corona, responsible for the primary X-ray continuum; and (d) reflection from the mid/outer part of the disc. The two coronae are suggested to be rather compact, with R-hot less than or similar to R-warm less than or similar to 10 r(g). Our SED analysis implies that Ton S180 accretes at super-Eddington rates. This is a key condition for the launch of a wind, marginal (i.e. 3.1 sigma significance) evidence of which is indeed found in the RGS spectrum.