Mapping the circumnuclear regions of the Circinus galaxy with the Imaging X-ray Polarimetry Explorer

DOI: 
10.1093/mnras/stac3189
Publication date: 
15/02/2023
Main author: 
Ursini, F.
IAA authors: 
Agudo, I.
Authors: 
Ursini, F.;Marinucci, A.;Matt, G.;Bianchi, S.;Marin, F.;Marshall, H. L.;Middei, R.;Poutanen, J.;Rogantini, D.;De Rosa, A.;Di Gesu, L.;García, J. A.;Ingram, A.;Kim, D. E.;Krawczynski, H.;Puccetti, S.;Soffitta, P.;Svoboda, J.;Tombesi, F.;Weisskopf, M. C.;Barnouin, T.;Perri, M.;Podgorny, J.;Ratheesh, A.;Zaino, A.;Agudo, I.;Antonelli, L. A.;Bachetti, M.;Baldini, L.;Baumgartner, W. H.;Bellazzini, R.;Bongiorno, S. D.;Bonino, R.;Brez, A.;Bucciantini, N.;Capitanio, F.;Castellano, S.;Cavazzuti, E.;Ciprini, S.;Costa, E.;Del Monte, E.;Di Lalla, N.;Di Marco, A.;Donnarumma, I.;Doroshenko, V.;Dovciak, M.;Ehlert, S. R.;Enoto, T.;Evangelista, Y.;Fabiani, S.;Ferrazzoli, R.;Gunji, S.;Heyl, J.;Iwakiri, W.;Jorstad, S. G.;Karas, V.;Kitaguchi, T.;Kolodziejczak, J. J.;La Monaca, F.;Latronico, L.;Liodakis, I.;Maldera, S.;Manfreda, A.;Marscher, A. P.;Mitsuishi, I.;Mizuno, T.;Muleri, F.;Ng, C. Y.;O'Dell, S. L.;Omodei, N.;Oppedisano, C.;Papitto, A.;Pavlov, G. G.;Peirson, A. L.;Pesce-Rollins, M.;Petrucci, P. -O.;Pilia, M.;Possenti, A.;Ramsey, B. D.;Rankin, J.;Romani, R. W.;Sgrò, C.;Slane, P.;Spandre, G.;Tamagawa, T.;Tavecchio, F.;Taverna, R.;Tawara, Y.;Tennant, A. F.;Thomas, N. E.;Trois, A.;Tsygankov, S. S.;Turolla, R.;Vink, J.;Wu, K.;Xie, F.;Zane, S.
Journal: 
Monthly Notices of the Royal Astronomical Society
Publication type: 
Article
Volume: 
519
Pages: 
50
Abstract: 
We report on the Imaging X-ray Polarimetry Explorer (IXPE) observation of the closest and X-ray brightest Compton-thick active galactic nucleus (AGN), the Circinus galaxy. We find the source to be significantly polarized in the 2-6 keV band. From previous studies, the X-ray spectrum is known to be dominated by reflection components, both neutral (torus) and ionized (ionization cones). Our analysis indicates that the polarization degree is 28 ± 7 per cent (at 68 per cent confidence level) for the neutral reflector, with a polarization angle of 18° ± 5°, roughly perpendicular to the radio jet. The polarization of the ionized reflection is unconstrained. A comparison with Monte Carlo simulations of the polarization expected from the torus shows that the neutral reflector is consistent with being an equatorial torus with a half-opening angle of 45°-55°. This is the first X-ray polarization detection in a Seyfert galaxy, demonstrating the power of X-ray polarimetry in probing the geometry of the circumnuclear regions of AGNs, and confirming the basic predictions of standard Unification Models.
Database: 
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2023MNRAS.519...50U/abstract
ADS Bibcode: 
2023MNRAS.519...50U
Keywords: 
polarization;scattering;galaxies: active;galaxies: individual: Circinus;galaxies: Seyfert;X-rays: galaxies;Astrophysics - High Energy Astrophysical Phenomena