TY - JOUR A1 - La Monaca, F A1 - Di Marco, A A1 - Poutanen, J A1 - Bachetti, M A1 - Motta, SE A1 - Papitto, A A1 - Pilia, M A1 - Xie, F A1 - Bianchi, S A1 - Bobrikova, A A1 - Costa, E A1 - Deng, W A1 - Ge, MY A1 - Illiano, G A1 - Jia, SM A1 - Krawczynski, H A1 - Lai, EV A1 - Liu, K A1 - Mastroserio, G A1 - Muleri, F A1 - Rankin, J A1 - Soffitta, P A1 - Veledina, A A1 - Ambrosino, F A1 - Del Santo, M A1 - Chen, W A1 - Garcia, JA A1 - Kaaret, P A1 - Russell, TD A1 - Wei, WH A1 - Zhang, SN A1 - Zuo, C A1 - Arzoumanian, Z A1 - Cocchi, M A1 - Gnarini, A A1 - Farinelli, R A1 - Gendreau, K A1 - Ursini, F A1 - Weisskopf, MC A1 - Zane, S A1 - Agudo, I A1 - Antonelli, LA A1 - Baldini, L A1 - Baumgartner, WH A1 - Bellazzini, R A1 - Bongiorno, SD A1 - Bonino, R A1 - Brez, A A1 - Bucciantini, N A1 - Capitanio, F A1 - Castellano, S A1 - Cavazzuti, E A1 - Chen, CT A1 - Ciprini, S A1 - De Rosa, A A1 - Del Monte, E A1 - Di Gesu, L A1 - Di Lalla, N A1 - Donnarumma, I A1 - Doroshenko, V A1 - Dov?iak, M A1 - Ehlert, SR A1 - Enoto, T A1 - Evangelista, Y A1 - Fabiani, S A1 - Ferrazzoli, R A1 - Gunji, S A1 - Hayashida, K A1 - Heyl, J A1 - Iwakiri, W A1 - Jorstad, SG A1 - Karas, V A1 - Kislat, F A1 - Kitaguchi, T A1 - Kolodziejczak, JJ A1 - Latronico, L A1 - Liodakis, I A1 - Maldera, S A1 - Manfreda, A A1 - Marin, F A1 - Marinucci, A A1 - Marscher, AP A1 - Marshall, HL A1 - Massaro, F A1 - Matt, G A1 - Mitsuishi, I A1 - Mizuno, T A1 - Negro, M A1 - Ng, CY A1 - O?Dell, SL A1 - Omodei, N A1 - Oppedisano, C A1 - Pavlov, GG A1 - Peirson, AL A1 - Perri, M A1 - Pesce-Rollins, M A1 - Petrucci, PO A1 - Possenti, A A1 - Puccetti, S A1 - Ramsey, BD JF - The Astrophysical Journal Letters N1 - Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence, https://creativecommons.org/licenses/by/4.0/. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. VL - 960 IS - 2 N2 - The Imaging X-ray Polarimetry Explorer measured with high significance the X-ray polarization of the brightest Z-source, Sco X-1, resulting in the nominal 2?8 keV energy band in a polarization degree of 1.0% ± 0.2% and a polarization angle of 8° ± 6° at a 90% confidence level. This observation was strictly simultaneous with observations performed by NICER, NuSTAR, and Insight-HXMT, which allowed for a precise characterization of its broadband spectrum from soft to hard X-rays. The source has been observed mainly in its soft state, with short periods of flaring. We also observed low-frequency quasiperiodic oscillations. From a spectropolarimetric analysis, we associate a polarization to the accretion disk at <3.2% at 90% confidence level, compatible with expectations for an electron scattering dominated optically thick atmosphere at the Sco X-1 inclination of ?44°; for the higher-energy Comptonized component, we obtain a polarization of 1.3% ± 0.4%, in agreement with expectations for a slab of Thomson optical depth of ?7 and an electron temperature of ?3 keV. A polarization rotation with respect to previous observations by OSO-8 and PolarLight, and also with respect to the radio-jet position angle, is observed. This result may indicate a variation of the polarization with the source state that can be related to relativistic precession or a change in the corona geometry with the accretion flow. ID - discovery10186104 UR - https://doi.org/10.3847/2041-8213/ad132d TI - Highly Significant Detection of X-Ray Polarization from the Brightest Accreting Neutron Star Sco X-1 SN - 2041-8205 Y1 - 2024/01/10/ AV - public ER -