Examinando por Autor "Miniutti, G."

Mostrando 1 - 4 de 4

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.
Restringido
Detection of a possible multiphase ultra-fast outflow in IRAS 13349+2438 with NuSTAR and XMM-Newton.
(Oxford Academics: Blackwell Publishing, 2020-08-25) Parker, M. L.; Matzeu, G. A.; Alston, W. N.; Fabian, A. C.; Lobban, A.; Miniutti, G.; Pinto, C.; Santos Lleó, M.; Schartel, N.; European Space Agency (ESA); 0000-0002-5635-5340; 0000-0003-1994-5322; 0000-0003-2658-6559; 0000-0001-5948-8360; 0000-0003-2532-7379; 0000-0002-9378-4072; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We present joint NuSTAR and XMM–Newton observations of the bright, variable quasar IRAS 13349+2438. This combined data set shows two clear iron absorption lines at 8 and 9 keV, which are most likely associated with two layers of mildly relativistic blueshifted absorption, with velocities of ∼0.14c and ∼0.27c. We also find strong evidence for a series of Ly α absorption lines at intermediate energies in a stacked XMM–Newton EPIC-pn spectrum, at the same blueshift as the lower velocity iron feature. This is consistent with a scenario where an outflowing wind is radially stratified, so faster, higher ionization material is observed closer to the black hole, and cooler, slower material is seen from streamlines at larger radii.
Acceso Abierto
Estimating the Jet Power of Mrk 231 during the 2017–2018 Flare
(The Institute of Physics (IOP), 2020-03-04) Reynolds, C. S.; Punsly, B.; Miniutti, G.; O´Dea, C. P.; Huerley Walker, N.; Agencia Estatal de Investigación (AEI); Punsly, B. [0000-0002-9448-2527]; Hurley Walker, N. [0000-0002-5119-4808]; Reynolds, C. [0000-0002-8978-0626]; O´Dea, C. [0000-0001-6421-054X]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Long-term 17.6 GHz radio monitoring of the broad absorption-line quasar, Mrk 231, detected a strong flare in late 2017. This triggered four epochs of Very Long Baseline Array (VLBA) observations from 8.4 to 43 GHz over a 10 week period as well as an X-ray observation with NuSTAR. This was the third campaign of VLBA monitoring that we have obtained. The 43 GHz VLBA was degraded in all epochs, with only 7 of 10 antennas available in three epochs and 8 in the first epoch. However, useful results were obtained due to a fortuitous capturing of a complete, short 100 mJy flare at 17.6 GHz, both growth and decay. This provided useful constraints on the physical model of the ejected plasma that were not available in previous campaigns. We consider four classes of models: discrete ejections (both protonic and positronic) and jetted (protonic and positronic). The most viable model is a "dissipative bright knot" in a faint background leptonic jet with an energy flux ~1043 erg s−1. Inverse Compton scattering calculations (based on these models) in the ambient quasar photon field explains the lack of a detectable increase in X-ray luminosity measured by NuSTAR. We show that the core (the bright knot) moves toward a nearby secondary at ≈0.97c. The background jet is much fainter. Evidently, the high-frequency VLBA core does not represent the point of origin of blazar jets, in general, and optical depth "core shift" estimates of jet points of origin can be misleading.
Acceso Abierto
Rapid late-time X-ray brightening of the tidal disruption event OGLE16aaa
(EDP Sciences, 2020-07-16) Kajava, J. J. E.; Giustini, M.; Saxton, R. D.; Miniutti, G.; Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Kajava, J. J. E. [0000-0002-3010-8333]; Giustini, M. [0000-0002-1329-658X]; Unidad de Excelencia Científica María de Maeztu del Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Stars that pass too close to a super-massive black hole may be disrupted by strong tidal forces. OGLE16aaa is one such tidal disruption event (TDE) which rapidly brightened and peaked in the optical/UV bands in early 2016 and subsequently decayed over the rest of the year. OGLE16aaa was detected in an XMM-Newton X-ray observation on June 9, 2016 with a flux slightly below the Swift/XRT upper limits obtained during the optical light curve peak. Between June 16–21, 2016, Swift/XRT also detected OGLE16aaa and based on the stacked spectrum, we could infer that the X-ray luminosity had jumped up by more than a factor of ten in just one week. No brightening signal was seen in the simultaneous optical/UV data to cause the X-ray luminosity to exceed the optical/UV one. A further XMM-Newton observation on November 30, 2016 showed that almost a year after the optical/UV peak, the X-ray emission was still at an elevated level, while the optical/UV flux decay had already leveled off to values comparable to those of the host galaxy. In all X-ray observations, the spectra were nicely modeled with a 50–70 eV thermal component with no intrinsic absorption, with a weak X-ray tail seen only in the November 30 XMM-Newton observation. The late-time X-ray behavior of OGLE16aaa strongly resembles the tidal disruption events ASASSN-15oi and AT2019azh. We were able to pinpoint the time delay between the initial optical TDE onset and the X-ray brightening to 182 ± 5 days, which may possibly represent the timescale between the initial circularization of the disrupted star around the super-massive black hole and the subsequent delayed accretion. Alternatively, the delayed X-ray brightening could be related to a rapid clearing of a thick envelope that covers the central X-ray engine during the first six months.