Browsing by Author "Matt, G."
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Item A deep X-ray view of the bare AGN Ark 120 VI. Geometry of the hot corona from spectroscopic and polarization signatures(ESO, 2018-11-30) Marinucci, A.; Porquet, D.; Tamborra, F.; Bianchi, S.; Braito, V.; Lobban, A.; Marin, F.; Matt, G.; Middei, R.; Nardini, E.; Reeves, J.; Tortosa, A.Context. The spectral shape of the hard X-ray continuum of active galactic nuclei (AGN) can be ascribed to inverse Compton scattering of optical/UV seed photons from the accretion disc by a hot corona of electrons. This physical process produces a polarization signal which is strongly sensitive to the geometry of the scattering medium (i.e., the hot corona) and of the radiation field. Aims. MoCA (Monte Carlo code for Comptonisation in Astrophysics) is a versatile code which allows for di erent geometries and configurations to be tested for Compton scattering in compact objects. A single photon approach is considered as well as polarisation and Klein-Nishina e ects. For this work, we selected four di erent geometries for the scattering electrons cloud above the accretion disc, namely an extended slab, an extended spheroid and two compact spheroids. Methods. We discuss the first application of the MoCA model to reproduce the hard X-ray primary continuum of the bare Seyfert 1 galaxy Ark 120, using different geometries for the hot corona above the accretion disc. The lack of extragalactic absorption along the line of sight makes it an excellent target for studying the accretion disc-corona system. We report on the spectral analysis of the simultaneous 2013 and 2014 XMM-Newton and NuSTAR observations of the source. Results. A general agreement is found between the best fit values of the hot coronal parameters obtained with MoCA and those inferred using other Comptonisation codes from the literature. The expected polarization signal from the best fits with MoCA is then presented and discussed, in view of the launch in 2021 of the Imaging X-ray Polarimetry Explorer (IXPE). Conclusions. We find that none of the tested geometries for the hot corona (extended slab and extended or compact spheroids) can be statistically preferred, based on spectroscopy solely. In the future, an IXPE observation less than 1 Ms long will clearly distinguish between an extended slab or a spherical hot corona.Item The lively accretion disk in NGC 2992. I. Transient iron K emission lines in the high flux state(2020-06-09) Marinucci, A.; Bianchi, S.; Braito, V.; De Marco, B.; Matt, G.; Middei, R.; Nardini, E.; Reeves, J. N.We report on one of the brightest flux levels of the Seyfert 2 galaxy NGC 2992 ever observed in X-rays, on May 2019. The source has been monitored every few days from March 26, 2019 to December 14, 2019 by Swift-XRT, and simultaneous XMM-Newton (250 ks) and NuSTAR (120 ks) observations were triggered on May 6, 2019. The high count rate of the source (its 2-10 keV flux ranged between 0.7 and 1.0×10⁻¹⁰ erg cm⁻² s⁻¹) allows us to perform a time-resolved spectroscopy, probing spatial scales of tens of gravitational radii from the central black hole. By constructing a map of the excess emission over the primary continuum, we find several emission structures in the 5.0-7.2 keV energy band. From fitting the 50 EPIC pn spectral slices of ∼5 ks duration, we interpret them as a constant narrow iron Kα line and three variable components in the iron K complex. When a self-consistent model accounting for the accretion disk emission is considered (KYNrline), two of these features (in the 5.0-5.8 keV and 6.8-7.2 keV bands) can be ascribed to a flaring region of the accretion disk located at rin≃15-40 rg from the black hole. The third one (6.5-6.8 keV) is likely produced at much larger radii (rin>50 rg). The inner radius and the azimuthal extension retrieved from the coadded spectra of the flaring states are rin=15±3 rg and ϕ=165∘−330∘, suggesting that the emitting region responsible for the broad iron K component is a relatively compact annular sector within the disk. Our findings support a physical scenario in which the accretion disk in NGC 2992 becomes more active at high accretion rates (Lbol/LEdd≥4%).Item NuSTAR AND XMM-NEWTON OBSERVATIONS OF THE HARD X-RAY SPECTRUM OF CENTAURUS A(IOP, 2016-03-08) Fürst, F.; Müller, C.; Madsen, K. K.; Lanz, L.; Rivers, E.; Brightman, M.; Arevalo, P.; Baloković, M.; Beuchert, T.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Dauser, T.; Farrah, D.; Graefe, C.; Hailey, C. J.; Harrison, F. A.; Kadler, M.; King, A.; Krauß, F.; Madejski, G.; Matt, G.; Marinucci, A.; Markowitz, A.; Ogle, P.; Ojha, R.; Rothschild, R.; Stern, D.; Walton, D. J.; Wilms, J.; Zhang, W.We present simultaneous XMM-Newton and Nuclear Spectroscopic Telescope Array (NuSTAR) observations spanning 3–78 keV of the nearest radio galaxy, Centaurus A (Cen A). The accretion geometry around the central engine in Cen A is still debated, and we investigate possible configurations using detailed X-ray spectral modeling. NuSTAR imaged the central region of Cen A with subarcminute resolution at X-ray energies above 10 keV for the first time, but found no evidence for an extended source or other off-nuclear point sources. The XMM-Newton and NuSTAR spectra agree well and can be described with an absorbed power law with a photon index Γ = 1.815 ± 0.005 and a fluorescent Fe K⍺ line in good agreement with literature values. The spectrum does not require a high-energy exponential rollover, with a constraint of Efold > 1 MeV. A thermal Comptonization continuum describes the data well, with parameters that agree with values measured by INTEGRAL, in particular an electron temperature kTₑ between ≈100–300 keV and seed photon input temperatures between 5 and 50 eV. We do not find evidence for reflection or a broad iron line and put stringent upper limits of R < 0.01 on the reflection fraction and accretion disk illumination. We use archival Chandra data to estimate the contribution from diffuse emission, extra-nuclear point sources, and the outer X-ray jet to the observed NuSTAR and XMM-Newton X-ray spectra and find the contribution to be negligible. We discuss different scenarios for the physical origin of the observed hard X-ray spectrum and conclude that the inner disk is replaced by an advection-dominated accretion flow or that the X-rays are dominated by synchrotron self-Compton emission from the inner regions of the radio jet or a combination thereof.Item X-ray polarization measurement of the gold standard of radio-quiet active galactic nuclei : NGC 1068(2024-03-04) Marin, F.; Marinucci, A.; Laurenti, M.; Kim, D. E.; Barnouin, T.; Di Marco, A.; Ursini, F.; Bianchi, S.; Ravi, S.; Marshall, H. L.; Matt, G.; Chen, C.-T.; Gianolli, V. E.; Ingram, A.; Maksym, W. P.; Panagiotou, C.; Podgorny, J.; Puccetti, S.; Ratheesh, A.; Tombesi, F.; Agudo, I.; Antonelli, L. A.; Bachetti, M.; Baldini, L.; Baumgartner, W.; Bellazzini, R.; Bongiorno, S.; Bonino, R.; Brez, A.; Bucciantini, N.; Capitanio, F.; Castellano, S.; Cavazzuti, E.; Ciprini, S.; Costa, E.; De Rosa, A.; Del Monte, E.; Di Gesu, L.; Di Lalla, N.; Donnarumma, I.; Doroshenko, V.; Dovciak, M.; Ehlert, S.; Enoto, T.; Evangelista, Y.; Fabiani, S.; Ferrazzoli, R.; Garcia, J.; Gunji, S.; Heyl, J.; Iwakiri, W.; Jorstad, S.; Kaaret, P.; Karas, V.; Kislat, F.; Kitaguchi, T.; Kolodziejczak, J.; Krawczynski, H.; La Monaca, F.; Latronico, L.; Liodakis, I.; Madejski, G.; Maldera, S.; Manfreda, A.; Marscher, A.; Massaro, F.; Mitsuishi, I.; Mizuno, T.; Muleri, F.; Negro, Michela; Ng, S.; O'Dell, S.; Omodei, N.; Oppedisano, C.; Papitto, A.; Pavlov, G.; Perri, M.; Pesce-Rollins, M.; Petrucci, P.-O.; Pilia, M.; Possenti, A.; Poutanen, J.; Ramsey, B.; Rankin, J.; Roberts, O.; Romani, R.; Sgro, C.; Slane, P.; Soffitta, P.; Spandre, G.; Swartz, D.; Tamagawa, T.; Tavecchio, F.; Taverna, R.; Tawara, Y.; Tennant, A.; Thomas, N.; Trois, A.; Tsygankov, S.; Turolla, R.; Vink, J.; Weisskopf, M.; Wu, K.; Xie, F.; Zane, S.We used the Imaging X-ray Polarimetry Explorer (IXPE) satellite to measure, for the first time, the 2-8 keV polarization of NGC 1068. We pointed IXPE for a net exposure time of 1.15 Ms on the target, in addition to two ~ 10 ks each Chandra snapshots in order to account for the potential impact of several ultraluminous X-ray source (ULXs) within IXPE's field-of-view. We measured a 2 - 8 keV polarization degree of 12.4% +/- 3.6% and an electric vector polarization angle of 101° +/- 8° at 68% confidence level. If we exclude the spectral region containing the bright Fe K lines and other soft X-ray lines where depolarization occurs, the polarization fraction rises up to 21.3% +/- 6.7% in the 3.5 - 6.0 keV band, with a similar polarization angle. The observed polarization angle is found to be perpendicular to the parsec scale radio jet. Using a combined Chandra and IXPE analysis plus multi-wavelength constraints, we estimated that the circumnuclear "torus" may sustain a half-opening angle of 50° - 55° (from the vertical axis of the system). Thanks to IXPE, we have measured the X-ray polarization of NGC 1068 and found comparable results, both in terms of polarization angle orientation with respect to the radio-jet and torus half-opening angle, to the X-ray polarimetric measurement achieved for the other archetypal Compton-thick AGN : the Circinus galaxy. Probing the geometric arrangement of parsec-scale matter in extragalactic object is now feasible thanks to X-ray polarimetry.