A deep X-ray view of the bare AGN Ark 120 VI. Geometry of the hot corona from spectroscopic and polarization signatures

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dc.contributor.authorMarinucci, A.
dc.contributor.authorPorquet, D.
dc.contributor.authorTamborra, F.
dc.contributor.authorBianchi, S.
dc.contributor.authorBraito, V.
dc.contributor.authorLobban, A.
dc.contributor.authorMarin, F.
dc.contributor.authorMatt, G.
dc.contributor.authorMiddei, R.
dc.contributor.authorNardini, E.
dc.contributor.authorReeves, J.
dc.contributor.authorTortosa, A.
dc.date.accessioned2019-02-08T18:54:13Z
dc.date.available2019-02-08T18:54:13Z
dc.date.issued2018-11-30
dc.description.abstractContext. 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.en_US
dc.description.sponsorshipWe thank the anonymous referee for her/his comments. AM thanks Craig Gordon for useful suggestions about generating the MoCA xspec tables. AM, GM acknowledge financial support from the Italian Space Agency under grant ASI/INAF I/037/12/0-011/13. SB acknowledges financial support from the Italian Space Agency under grant ASI-INAF I/037/12/0. AM, GM, SB, RM, AT acknowledge financial support from ASIINAF 2017-12-H.0. AL acknowledges support from STFC consolidated grant ST/M001040/1. FM would like to thank the Centre National d’Ètudes Spatiales (CNES) who funded this project through to the post-doctoral grant “Probing the geometry and physics of active galactic nuclei with ultraviolet and X-ray polarized radiative transfer”. EN acknowledges funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłlodowska-Curie grant agreement No. 664931.en_US
dc.description.urihttps://www.aanda.org/articles/aa/pdf/forth/aa34454-18.pdfen_US
dc.format.extent9 pagesen_US
dc.genrejournal articles postprintsen_US
dc.identifierdoi:10.13016/m2bpbg-o0gy
dc.identifier.citationA. Marinucci, D. Porquet, F. Tamborra, S. Bianchi, V. Braito, A. Lobban, F. Marin, G. Matt, R. Middei, E. Nardini, J. Reeves and A. Tortosa, A deep X-ray view of the bare AGN Ark 120 VI. Geometry of the hot corona from spectroscopic and polarization signatures, Astronomy & Astrophysics manuscript no. ark120_papVI, 2018 , https://www.aanda.org/articles/aa/pdf/forth/aa34454-18.pdfen_US
dc.identifier.urihttp://hdl.handle.net/11603/12751
dc.language.isoen_USen_US
dc.publisherESOen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Center for Space Sciences and Technology
dc.rightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
dc.rightsReproduced with permission from Astronomy & Astrophysics, © ESO
dc.subjectgalaxies:activeen_US
dc.subjectgalaxies: seyferten_US
dc.subjectgalaxies: accretionen_US
dc.subjectindividual: ark 120en_US
dc.titleA deep X-ray view of the bare AGN Ark 120 VI. Geometry of the hot corona from spectroscopic and polarization signaturesen_US
dc.typeTexten_US

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