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.

Di Marco, A., La Monaca, F., Poutanen, J., Russell, T.d., Anitra, A., Farinelli, R., et al. (2023). First detection of X-ray polarization from the accreting neutron star 4U 1820−303. THE ASTROPHYSICAL JOURNAL LETTERS, 953(2) [10.3847/2041-8213/acec6e].

First detection of X-ray polarization from the accreting neutron star 4U 1820−303

Tombesi F.;
2023-01-01

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.
2023
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore FIS/05
English
Con Impact Factor ISI
Di Marco, A., La Monaca, F., Poutanen, J., Russell, T.d., Anitra, A., Farinelli, R., et al. (2023). First detection of X-ray polarization from the accreting neutron star 4U 1820−303. THE ASTROPHYSICAL JOURNAL LETTERS, 953(2) [10.3847/2041-8213/acec6e].
Di Marco, A; La Monaca, F; Poutanen, J; Russell, Td; Anitra, A; Farinelli, R; Mastroserio, G; Muleri, F; Xie, F; Bachetti, M; Burderi, L; Carotenuto, F; Del Santo, M; Di Salvo, T; Dovciak, M; Gnarini, A; Iaria, R; Kajava, Jje; Liu, K; Middei, R; O'Dell, Sl; Pilia, M; Rankin, J; Sanna, A; Eijnden, Jvd; Weisskopf, Mc; Bobrikova, A; Capitanio, F; Costa, E; Kaaret, P; Marino, A; Soffitta, P; Ursini, F; Ambrosino, F; Cocchi, M; Fabiani, S; Marshall, Hl; Matt, G; Motta, Se; Papitto, A; Stella, L; Tarana, A; Zane, S; Agudo, I; Antonelli, La; Baldini, L; Baumgartner, Wh; Bellazzini, R; Bianchi, S; Bongiorno, Sd; Bonino, R; Brez, A; Bucciantini, N; Castellano, S; Cavazzuti, E; Chen, C-; Ciprini, S; De Rosa, A; Del Monte, E; Di Gesu, L; Di Lalla, N; Donnarumma, I; Doroshenko, V; Ehlert, Sr; Enoto, T; Evangelista, Y; 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; Marinucci, A; Marscher, Ap; Massaro, F; Mitsuishi, I; Mizuno, T; Negro, M; Ng, C-; Omodei, N; Oppedisano, C; Pavlov, Gg; Peirson, Al; Perri, M; Pesce-Rollins, M; Petrucci, P-; Possenti, A; Puccetti, S; Ramsey, Bd; Ratheesh, A; Roberts, Oj; Romani, Rw; Sgro, C; Slane, P; Spandre, G; Swartz, Da; Tamagawa, T; Tavecchio, F; Taverna, R; Tawara, Y; Tennant, Af; Thomas, Ne; Tombesi, F; Trois, A; Tsygankov, Ss; Turolla, R; Vink, J; Wu, K
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/339558
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