Mapping the circumnuclear regions of the Circinus galaxy with the Imaging X-ray Polarimetry Explorer
Creators: name: Ursini, F.
name: Marinucci, A.
name: Matt, G.
name: Bianchi, S.
name: Marin, F.
name: Marshall, H. L.
name: Middei, R.
name: Poutanen, J.
name: Rogantini, D.
name: De Rosa, A.
name: Di Gesu, L.
name: García, J. A.
name: Ingram, A.
name: Kim, D. E.
name: Krawczynski, H.
name: Puccetti, S.
name: Soffitta, P.
name: Svoboda, J.
name: Tombesi, F.
name: Weisskopf, M. C.
name: Barnouin, T.
name: Perri, M.
name: Podgorny, J.
name: Ratheesh, A.
name: Zaino, A.
name: Agudo, I.
name: Antonelli, L. A.
name: Bachetti, M.
name: Baldini, L.
name: Baumgartner, W. H.
name: Bellazzini, R.
name: Bongiorno, S. D.
name: Bonino, R.
name: Brez, A.
name: Bucciantini, N.
name: Capitanio, F.
name: Castellano, S.
name: Cavazzuti, E.
name: Ciprini, S.
name: Costa, E.
name: Del Monte, E.
name: Di Lalla, N.
name: Di Marco, A.
name: Donnarumma, I.
name: Doroshenko, V.
name: Dovčiak, M.
name: Ehlert, S. R.
name: Enoto, T.
name: Evangelista, Y.
name: Fabiani, S.
name: Ferrazzoli, R.
name: Gunji, S.
name: Heyl, J.
name: Iwakiri, W.
name: Jorstad, S. G.
name: Karas, V.
name: Kitaguchi, T.
name: Kolodziejczak, J. J.
name: La Monaca, F.
name: Latronico, L.
name: Liodakis, I.
name: Maldera, S.
name: Manfreda, A.
name: Marscher, A. P.
name: Mitsuishi, I.
name: Mizuno, T.
name: Muleri, F.
name: Ng, C. Y.
name: O'Dell, S. L.
name: Omodei, N.
name: Oppedisano, C.
name: Papitto, A.
name: Pavlov, G. G.
name: Peirson, A. L.
name: Pesce-Rollins, M.
name: Petrucci, P. -O.
name: Pilia, M.
name: Possenti, A.
name: Ramsey, B. D.
name: Rankin, J.
name: Romani, R. W.
name: Sgrò, C.
name: Slane, P.
name: Spandre, G.
name: Tamagawa, T.
name: Tavecchio, F.
name: Taverna, R.
name: Tawara, Y.
name: Tennant, A. F.
name: Thomas, N. E.
name: Trois, A.
name: Tsygankov, S. S.
name: Turolla, R.
name: Vink, J.
name: Wu, K.
name: Xie, F.
name: Zane, S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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 $28 \pm 7$ per cent (at 68 per cent confidence level) for the neutral reflector, with a polarization angle of $18° \pm 5°$, 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.
description: 9 pages, accepted for publication in MNRAS, authors list updated