First Detection of X-Ray Polarization from the Accreting Neutron Star 4U 1820−303
Date Issued
2023
Author(s)
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Poutanen, Juri
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Russell, Thomas D.
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Roberts, Oliver J.
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Romani, Roger W.
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Sgrò, Carmelo
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Slane, Patrick
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Spandre, Gloria
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Swartz, Douglas A.
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Tamagawa, Toru
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Taverna, Roberto
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Tawara, Yuzuru
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Tennant, Allyn F.
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Thomas, Nicholas E.
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Tsygankov, Sergey S.
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Turolla, Roberto
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Vink, Jacco
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Wu, Kinwah
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Di Salvo, Tiziana
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Dovčiak, Michal
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Gnarini, Andrea
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Kajava, Jari J. E.
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Liu, Kuan
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O’Dell, Stephen L.
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Eijnden, Jakob van den
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Weisskopf, Martin C.
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Bobrikova, Anna
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Kaaret, Philip
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Marshall, Herman L.
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Zane, Silvia
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Agudo, Iván
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Baldini, Luca
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Baumgartner, Wayne H.
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Bellazzini, Ronaldo
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Bianchi, Stefano
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Bongiorno, Stephen D.
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Bonino, Raffaella
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Brez, Alessandro
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Castellano, Simone
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Cavazzuti, Elisabetta
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Chen, Chien-Ting
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Ciprini, Stefano
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Di Gesu, Laura
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Di Lalla, Niccolò
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Donnarumma, Immacolata
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Doroshenko, Victor
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Ehlert, Steven R.
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Enoto, Teruaki
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Garcia, Javier A.
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Gunji, Shuichi
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Hayashida, Kiyoshi
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Heyl, Jeremy
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Iwakiri, Wataru
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Jorstad, Svetlana G.
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Karas, Vladimir
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Kislat, Fabian
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Kitaguchi, Takao
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Kolodziejczak, Jeffery J.
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Krawczynski, Henric
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Latronico, Luca
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Liodakis, Ioannis
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Maldera, Simone
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Manfreda, Alberto
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Marin, Frédéric
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Marinucci, Andrea
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Marscher, Alan P.
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Mitsuishi, Ikuyuki
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Mizuno, Tsunefumi
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Negro, Michela
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Ng, Chi-Yung
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Omodei, Nicola
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Oppedisano, Chiara
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Pavlov, George G.
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Peirson, Abel L.
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Pesce-Rollins, Melissa
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Petrucci, Pierre-Olivier
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Puccetti, Simonetta
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Ramsey, Brian D.
Abstract
This paper reports the first detection of polarization in the X-rays for atoll-source 4U 1820-303, obtained with the Imaging X-ray Polarimetry Explorer (IXPE) at 99.999% confidence level (CL). Simultaneous polarimetric measurements were also performed in the radio with the Australia Telescope Compact Array. The IXPE observations of 4U 1820-303 were coordinated with Swift X-ray Telescope, Neutron Star Interior Composition Explorer, and Nuclear Spectroscopic Telescope Array aiming to obtain an accurate X-ray spectral model covering a broad energy interval. The source shows a significant polarization above 4 keV, with a polarization degree of 2.0% ± 0.5% and a polarization angle of -55° ± 7° in the 4-7 keV energy range, and a polarization degree of 10% ± 2% and a polarization angle of -67° ± 7° in the 7-8 keV energy bin. This polarization also shows a clear energy trend with polarization degree increasing with energy and a hint for a position-angle change of ≃90° at 96% CL around 4 keV. The spectro-polarimetric fit indicates that the accretion disk is polarized orthogonally to the hard spectral component, which is presumably produced in the boundary/spreading layer. We do not detect linear polarization from the radio counterpart, with a 3σ upper limit of 50% at 7.25 GHz.
Volume
953
Issue
2
Start page
L22
Issn Identifier
2041-8205
Ads BibCode
2023ApJ...953L..22D
Rights
open.access
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