Refereed journal article or data article (A1)
Mapping the circumnuclear regions of the Circinus galaxy with the Imaging X-ray Polarimetry Explorer
List of Authors: Ursini F, Marinucci A, Matt G, Bianchi S, Marin F, Marshall HL, Middei R, Poutanen J, Rogantini D, De Rosa A, Di Gesu L, Garcia JA, Ingram A, Kim DE, Krawczynski H, Puccetti S, Soffitta P, Svoboda J, Tombesi F, Weisskopf MC, Barnouin T, Perri M, Podgorny J, Ratheesh A, Zaino A, Agudo I, Antonelli LA, Bachetti M, Baldini L, Baumgartner WH, Bellazzini R, Bongiorno SD, 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 SR, Enoto T, Evangelista Y, Fabiani S, Ferrazzoli R, Gunji S, Heyl J, Iwakiri W, Jorstad SG, Karas V, Kitaguchi T, Kolodziejczak JJ, La Monaca F, Latronico L, Liodakis I, Maldera S, Manfreda A, Marscher AP, Mitsuishi I, Mizuno T, Muleri F, Ng CY, O'Dell SL, Omodei N, Oppedisano C, Papitto A, Pavlov GG, Peirson AL, Pesce-Rollins M, Petrucci PO, Pilia M, Possenti A, Ramsey BD, Rankin J, Romani RW, Sgro C, Slane P, Spandre G, Tamagawa T, Tavecchio F, Taverna R, Tawara Y, Tennant AF, Thomas NE, Trois A, Tsygankov SS, Turolla R, Vink J, Wu K, Xie F, Zane S
Publisher: OXFORD UNIV PRESS
Publication year: 2023
Journal: Monthly Notices of the Royal Astronomical Society
Journal name in source: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Journal acronym: MON NOT R ASTRON SOC
Volume number: 519
Issue number: 1
Start page: 50
End page: 58
Number of pages: 9
ISSN: 0035-8711
eISSN: 1365-2966
DOI: http://dx.doi.org/10.1093/mnras/stac3189
URL: https://doi.org/10.1093/mnras/stac3189
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/178952528
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 degrees +/- 5 degrees, 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 degrees-55 degrees. 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.
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