Uncovering the geometry of the hot X-ray corona in the Seyfert galaxy NGC4151 with IXPE
Creators: name: Gianolli, V. E.
name: Kim, D. E.
name: Bianchi, S.
name: Agís-González, B.
name: Madejski, G.
name: Marin, F.
name: Marinucci, A.
name: Matt, G.
name: Middei, R.
name: Petrucci, P-O.
name: Soffitta, P.
name: Tagliacozzo, D.
name: Tombesi, F.
name: Ursini, F.
name: Barnouin, T.
name: De Rosa, A.
name: Di Gesu, L.
name: Ingram, A.
name: Loktev, V.
name: Panagiotou, C.
name: Podgorny, J.
name: Poutanen, J.
name: Puccetti, S.
name: Ratheesh, A.
name: Veledina, A.
name: Zhang, W.
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: Chen, C. -T.
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: García, J. A.
name: Gunji, S.
name: Heyl, J.
name: Iwakiri, W.
name: Jorstad, S. G.
name: Kaaret, P.
name: Karas, V.
name: Kislat, F.
name: Kitaguchi, T.
name: Kolodziejczak, J. J.
name: Krawczynski, H.
name: La Monaca, F.
name: Latronico, L.
name: Liodakis, I.
name: Maldera, S.
name: Manfreda, A.
name: Marscher, A. P.
name: Marshall, H. L.
name: Massaro, F.
name: Mitsuishi, I.
name: Mizuno, T.
name: Muleri, F.
name: Negro, M.
name: Ng, C. -Y.
name: ODell, S. L.
name: Omodei, N.
name: Oppedisano, C.
name: Papitto, A.
name: Pavlov, G. G.
name: Peirson, A. L.
name: Perri, M.
name: Pesce-Rollins, M.
name: Pilia, M.
name: Possenti, A.
name: Ramsey, B. D.
name: Rankin, J.
name: Roberts, O. J.
name: Romani, R. W.
name: Sgrò, C.
name: Slane, P.
name: Spandre, G.
name: Swartz, D. A.
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: Weisskopf, M. C.
name: Wu, K.
name: Xie, F.
name: Zane, S.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We present an X-ray spectro-polarimetric analysis of the bright Seyfert galaxy NGC4151. The source has been observed with the Imaging X-ray Polarimetry Explorer (IXPE) for 700 ks, complemented with simultaneous XMM-Newton (50 ks) and NuSTAR (100 ks) pointings. A polarization degree $Π = 4.9 {\pm} 1.1 \%$ and angle $Ψ= 86° {\pm} 7°$ east of north ($68\%$ confidence level) are measured in the 2-8 keV energy range. The spectro-polarimetric analysis shows that the polarization could be entirely due to reflection. Given the low reflection flux in the IXPE band, this requires however a reflection with a very large ($&gt; 38 \%$) polarization degree. Assuming more reasonable values, a polarization degree of the hot corona ranging from ${\sim}4$ to ${\sim}8\%$ is found. The observed polarization degree excludes a spherical lamppost geometry for the corona, suggesting instead a slab-like geometry, possibly a wedge, as determined via Monte Carlo simulations. This is further confirmed by the X-ray polarization angle, which coincides with the direction of the extended radio emission in this source, supposed to match the disc axis. NGC4151 is the first AGN with an X-ray polarization measure for the corona, illustrating the capabilities of X-ray polarimetry and IXPE in unveiling its geometry.
description: 9 pages, 4 figures