eprintid: 10186249 rev_number: 7 eprint_status: archive userid: 699 dir: disk0/10/18/62/49 datestamp: 2024-01-30 12:15:58 lastmod: 2024-01-30 12:15:58 status_changed: 2024-01-30 12:15:58 type: article metadata_visibility: show sword_depositor: 699 creators_name: Rankin, J creators_name: La Monaca, F creators_name: Di Marco, A creators_name: Poutanen, J creators_name: Bobrikova, A creators_name: Kravtsov, V creators_name: Muleri, F creators_name: Pilia, M creators_name: Veledina, A creators_name: Fender, R creators_name: Kaaret, P creators_name: Kim, DE creators_name: Marinucci, A creators_name: Marshall, HL creators_name: Papitto, A creators_name: Tennant, AF creators_name: Tsygankov, SS creators_name: Weisskopf, MC creators_name: Wu, K creators_name: Zane, S creators_name: Ambrosino, F creators_name: Farinelli, R creators_name: Gnarini, A creators_name: Agudo, I creators_name: Antonelli, LA creators_name: Bachetti, M creators_name: Baldini, L creators_name: Baumgartner, WH creators_name: Bellazzini, R creators_name: Bianchi, S creators_name: Bongiorno, SD creators_name: Bonino, R creators_name: Brez, A creators_name: Bucciantini, N creators_name: Capitanio, F creators_name: Castellano, S creators_name: Cavazzuti, E creators_name: Chen, CT creators_name: Ciprini, S creators_name: Costa, E creators_name: De Rosa, A creators_name: Del Monte, E creators_name: Di Gesu, L creators_name: Di Lalla, N creators_name: Donnarumma, I creators_name: Doroshenko, V creators_name: Dovčiak, M creators_name: Ehlert, SR creators_name: Enoto, T creators_name: Evangelista, Y creators_name: Fabiani, S creators_name: Ferrazzoli, R creators_name: Garcia, JA creators_name: Gunji, S creators_name: Hayashida, K creators_name: Heyl, J creators_name: Iwakiri, W creators_name: Jorstad, SG creators_name: Karas, V creators_name: Kislat, F creators_name: Kitaguchi, T creators_name: Kolodziejczak, JJ creators_name: Krawczynski, H creators_name: Latronico, L creators_name: Liodakis, I creators_name: Maldera, S creators_name: Manfreda, A creators_name: Marin, F creators_name: Marscher, AP creators_name: Massaro, F creators_name: Matt, G creators_name: Mitsuishi, I creators_name: Mizuno, T creators_name: Negro, M creators_name: Ng, CY creators_name: O’Dell, SL creators_name: Omodei, N creators_name: Oppedisano, C creators_name: Pavlov, GG creators_name: Peirson, AL creators_name: Perri, M creators_name: Pesce-Rollins, M creators_name: Petrucci, PO creators_name: Possenti, A creators_name: Puccetti, S creators_name: Ramsey, BD creators_name: Ratheesh, A creators_name: Roberts, OJ creators_name: Romani, RW creators_name: Sgrò, C creators_name: Slane, P creators_name: Soffitta, P creators_name: Spandre, G creators_name: Swartz, DA creators_name: Tamagawa, T creators_name: Tavecchio, F creators_name: Taverna, R creators_name: Tawara, Y creators_name: Thomas, NE creators_name: Tombesi, F title: X-Ray Polarized View of the Accretion Geometry in the X-Ray Binary Circinus X-1 ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F63 note: Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. abstract: Cir X-1 is a neutron star X-ray binary characterized by strong variations in flux during its eccentric ∼16.6 day orbit. There are also strong variations in the spectral state, and it has historically shown both atoll and Z state properties. We observed the source with the Imaging X-ray Polarimetry Explorer during two orbital segments, 6 days apart, for a total of 263 ks. We find an X-ray polarization degree in these segments of 1.6% ± 0.3% and 1.4% ± 0.3% at polarization angles of 37° ± 5° and −12° ± 7°, respectively. Thus, we observed a rotation of the polarization angle by 49° ± 8° along the orbit. Because variations of accretion flow, and then of the hardness ratio, are expected during the orbit, we also studied the polarization binned in hardness ratio and found the polarization angle differing by 67° ± 11° between the lowest and highest values of the hardness ratio. We discuss possible interpretations of this result that could indicate a possible misalignment between the symmetry axes of the accretion disk and the Comptonizing region caused by the misalignment of the neutron star’s angular momentum with respect to the orbital one. date: 2024-01-20 date_type: published publisher: American Astronomical Society official_url: https://doi.org/10.3847/2041-8213/ad1832 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2142243 doi: 10.3847/2041-8213/ad1832 lyricists_name: Wu, Kinwah lyricists_name: Zane, Silvia lyricists_id: KWUXX50 lyricists_id: SZANE58 actors_name: Kalinowski, Damian actors_id: DKALI47 actors_role: owner full_text_status: public publication: Astrophysical Journal Letters volume: 961 number: 1 article_number: L8 issn: 2041-8205 citation: Rankin, J; La Monaca, F; Di Marco, A; Poutanen, J; Bobrikova, A; Kravtsov, V; Muleri, F; ... Tombesi, F; + view all <#> Rankin, J; La Monaca, F; Di Marco, A; Poutanen, J; Bobrikova, A; Kravtsov, V; Muleri, F; Pilia, M; Veledina, A; Fender, R; Kaaret, P; Kim, DE; Marinucci, A; Marshall, HL; Papitto, A; Tennant, AF; Tsygankov, SS; Weisskopf, MC; Wu, K; Zane, S; Ambrosino, F; Farinelli, R; Gnarini, A; Agudo, I; Antonelli, LA; Bachetti, M; Baldini, L; Baumgartner, WH; Bellazzini, R; Bianchi, S; Bongiorno, SD; Bonino, R; Brez, A; Bucciantini, N; Capitanio, F; Castellano, S; Cavazzuti, E; Chen, CT; Ciprini, S; Costa, E; De Rosa, A; Del Monte, E; Di Gesu, L; Di Lalla, N; Donnarumma, I; Doroshenko, V; Dovčiak, M; Ehlert, SR; Enoto, T; Evangelista, Y; Fabiani, S; Ferrazzoli, R; Garcia, JA; Gunji, S; Hayashida, K; Heyl, J; Iwakiri, W; Jorstad, SG; Karas, V; Kislat, F; Kitaguchi, T; Kolodziejczak, JJ; Krawczynski, H; Latronico, L; Liodakis, I; Maldera, S; Manfreda, A; Marin, F; Marscher, AP; Massaro, F; Matt, G; Mitsuishi, I; Mizuno, T; Negro, M; Ng, CY; O’Dell, SL; Omodei, N; Oppedisano, C; Pavlov, GG; Peirson, AL; Perri, M; Pesce-Rollins, M; Petrucci, PO; Possenti, A; Puccetti, S; Ramsey, BD; Ratheesh, A; Roberts, OJ; Romani, RW; Sgrò, C; Slane, P; Soffitta, P; Spandre, G; Swartz, DA; Tamagawa, T; Tavecchio, F; Taverna, R; Tawara, Y; Thomas, NE; Tombesi, F; - view fewer <#> (2024) X-Ray Polarized View of the Accretion Geometry in the X-Ray Binary Circinus X-1. Astrophysical Journal Letters , 961 (1) , Article L8. 10.3847/2041-8213/ad1832 <https://doi.org/10.3847/2041-8213%2Fad1832>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10186249/1/Wu_X-Ray%20Polarized%20View%20of%20the%20Accretion%20Geometry%20in%20the%20X-Ray%20Binary%20Circinus%20X-1_VoR.pdf