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Tracking the X-Ray Polarization of the Black Hole Transient Swift J1727.8–1613 during a State Transition

2024; IOP Publishing; Volume: 968; Issue: 2 Linguagem: Inglês

10.3847/1538-4357/ad3faf

1538-4357

Adam Ingram, Niek Bollemeijer, Alexandra Veledina, Michal Dovčiak, Juri Poutanen, E. Egron, T. D. Russell, С. А. Трушкин, Michela Negro, Ajay Ratheesh, Fiamma Capitanio, Riley Connors, Joey Neilsen, A. Kraus, M. N. Iacolina, A. Pellizzoni, M. Pilia, Francesco Carotenuto, G. Matt, Guglielmo Mastroserio, P. Kaaret, S. Bianchi, Javier A. García, Matteo Bachetti, Kinwah Wu, E. Costa, M. S. Ewing, Vadim Kravtsov, H. Krawczynski, Vladislav Loktev, Andrea Marinucci, Lorenzo Marra, Romana Mikušincová, Edward Nathan, Maxime Parra, Pierre-Olivier Petrucci, S. Righini, P. Soffitta, James F. Steiner, Jiří Svoboda, Francesco Tombesi, Stefano Tugliani, F. Ursini, Yi-Jung Yang, Silvia Zane, Wenda Zhang, I. Agudo, L. A. Antonelli, L. Baldini, W. H. Baumgartner, R. Bellazzini, Stephen D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, Simone Castellano, E. Cavazzuti, Chien‐Ting Chen, S. Ciprini, Alessandra De Rosa, E. Del Monte, Laura Di Gesu, Niccolò Di Lalla, Alessandro Di Marco, I. Donnarumma, Victor Doroshenko, Steven R. Ehlert, Teruaki Enoto, Y. Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, W. Iwakiri, Svetlana G. Jorstad, V. Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Fabio La Monaca, L. Latronico, Ioannis Liodakis, S. Maldera, Alberto Manfreda, Frédéric Marin, Alan P. Marscher, Herman L. Marshall, F. Massaro, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, C.‐Y. Ng, Stephen L. O’Dell, N. Omodei, C. Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, M. Perri, M. Pesce-Rollins, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, O. J. Roberts, Roger W. Romani, C. Sgrò, Patrick Slane, G. Spandre, Douglas A. Swartz, Toru Tamagawa, F. Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, A. Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Fei Xie,

Mechanics and Biomechanics Studies

Abstract We report on an observational campaign on the bright black hole (BH) X-ray binary Swift J1727.8–1613 centered around five observations by the Imaging X-ray Polarimetry Explorer. These observations track for the first time the evolution of the X-ray polarization of a BH X-ray binary across a hard to soft state transition. The 2–8 keV polarization degree decreased from ∼4% to ∼3% across the five observations, but the polarization angle remained oriented in the north–south direction throughout. Based on observations with the Australia Telescope Compact Array, we find that the intrinsic 7.25 GHz radio polarization aligns with the X-ray polarization. Assuming the radio polarization aligns with the jet direction (which can be tested in the future with higher-spatial-resolution images of the jet), our results imply that the X-ray corona is extended in the disk plane, rather than along the jet axis, for the entire hard intermediate state. This in turn implies that the long (≳10 ms) soft lags that we measure with the Neutron star Interior Composition ExploreR are dominated by processes other than pure light-crossing delays. Moreover, we find that the evolution of the soft lag amplitude with spectral state does not follow the trend seen for other sources, implying that Swift J1727.8–1613 is a member of a hitherto undersampled subpopulation.