학술논문
X-ray polarization measurement of the gold standard of radio-quiet active galactic nuclei : NGC 1068
Document Type
Working Paper
Author
Marin, F.; Marinucci, A.; Laurenti, M.; Kim, D. E.; Barnouin, T.; Di Marco, A.; Ursini, F.; Bianchi, S.; Ravi, S.; Marshall, H. L.; Matt, G.; Chen, C. -T.; Gianolli, V. E.; Ingram, A.; Maksym, W. P.; Panagiotou, C.; Podgorny, J.; Puccetti, S.; Ratheesh, A.; Tombesi, F.; Agudo, I.; Antonelli, L. A.; Bachetti, M.; Baldini, L.; Baumgartner, W.; Bellazzini, R.; Bongiorno, S.; Bonino, R.; Brez, A.; Bucciantini, N.; Capitanio, F.; Castellano, S.; Cavazzuti, E.; Ciprini, S.; Costa, E.; De Rosa, A.; Del Monte, E.; Di Gesu, L.; Di Lalla, N.; Donnarumma, I.; Doroshenko, V.; Dovciak, M.; Ehlert, S.; Enoto, T.; Evangelista, Y.; Fabiani, S.; Ferrazzoli, R.; Garcia, J.; Gunji, S.; Heyl, J.; Iwakiri, W.; Jorstad, S.; Kaaret, P.; Karas, V.; Kislat, F.; Kitaguchi, T.; Kolodziejczak, J.; Krawczynski, H.; La Monaca, F.; Latronico, L.; Liodakis, I.; Madejski, G.; Maldera, S.; Manfreda, A.; Marscher, A.; Massaro, F.; Mitsuishi, I.; Mizuno, T.; Muleri, F.; Negro, M.; Ng, S.; O'Dell, S.; Omodei, N.; Oppedisano, C.; Papitto, A.; Pavlov, G.; Perri, M.; Pesce-Rollins, M.; Petrucci, P. -O.; Pilia, M.; Possenti, A.; Poutanen, J.; Ramsey, B.; Rankin, J.; Roberts, O.; Romani, R.; Sgro, C.; Slane, P.; Soffitta, P.; Spandre, G.; Swartz, D.; Tamagawa, T.; Tavecchio, F.; Taverna, R.; Tawara, Y.; Tennant, A.; Thomas, N.; Trois, A.; Tsygankov, S.; Turolla, R.; Vink, J.; Weisskopf, M.; Wu, K.; Xie, F.; Zane, S.
Source
Subject
Language
Abstract
We used the Imaging X-ray Polarimetry Explorer (IXPE) satellite to measure, for the first time, the 2-8 keV polarization of NGC 1068. We pointed IXPE for a net exposure time of 1.15 Ms on the target, in addition to two ~ 10 ks each Chandra snapshots in order to account for the potential impact of several ultraluminous X-ray source (ULXs) within IXPE's field-of-view. We measured a 2 - 8 keV polarization degree of 12.4% +/- 3.6% and an electric vector polarization angle of 101{\deg} +/- 8{\deg} at 68% confidence level. If we exclude the spectral region containing the bright Fe K lines and other soft X-ray lines where depolarization occurs, the polarization fraction rises up to 21.3% +/- 6.7% in the 3.5 - 6.0 keV band, with a similar polarization angle. The observed polarization angle is found to be perpendicular to the parsec scale radio jet. Using a combined Chandra and IXPE analysis plus multi-wavelength constraints, we estimated that the circumnuclear "torus" may sustain a half-opening angle of 50{\deg} - 55{\deg} (from the vertical axis of the system). Thanks to IXPE, we have measured the X-ray polarization of NGC 1068 and found comparable results, both in terms of polarization angle orientation with respect to the radio-jet and torus half-opening angle, to the X-ray polarimetric measurement achieved for the other archetypal Compton-thick AGN : the Circinus galaxy. Probing the geometric arrangement of parsec-scale matter in extragalactic object is now feasible thanks to X-ray polarimetry.
Comment: 9 pages, 5 figures, 2 tables, submited to A&A
Comment: 9 pages, 5 figures, 2 tables, submited to A&A