Polarized x-rays constrain the disk-jet geometry in the black hole x-ray binary Cygnus X-1
Ingram, Adam; Wu, Kinwah; Enoto, Teruaki; Turolla, Roberto; Pavlov, George G.; Weisskopf, Martin C.; Tennant, Allyn F.; Slane, Patrick; Papitto, Alessandro; Miller, Jon M.; Hayashida, Kiyoshi; Vink, Jacco; Bianchi, Stefano; Matt, Giorgio; Kitaguchi, Takao; Doroshenko, Victor; Lutovinov, Alexander A.; Poutanen, Juri; Tombesi, Francesco; Mitsuishi, Ikuyuki; Mizuno, Tsunefumi; Tamagawa, Toru; Tawara, Yuzuru; Zane, Silvia; Dovčiak, Michal; Molkov, Sergey V.; Iwakiri, Wataru; Zhang, Wenda; Bachetti, Matteo; Rodriguez Cavero, Nicole; Tavecchio, Fabrizio; Thomas, Nicholas E.; Pesce-Rollins, Melissa; Marshall, Herman L.; Heyl, Jeremy; Ratheesh, Ajay; Marinucci, Andrea; De Rosa, Alessandra; Marin, Frédéric; Petrucci, Pierre-Olivier; Baumgartner, Wayne H.; Negro, Michela; Perri, Matteo; Taverna, Roberto; Muleri, Fabio; Di Marco, Alessandro; Krawczynski, Henric; Possenti, Andrea; Baldini, Luca; Agudo, Iván; Antonelli, Lucio A.; Bellazzini, Ronaldo; Bongiorno, Stephen D.; Bonino, Raffaella; Brez, Alessandro; Bucciantini, Niccolò; Capitanio, Fiamma; Castellano, Simone; Cavazzuti, Elisabetta; Ciprini, Stefano; Costa, Enrico; Del Monte, Ettore; Di Gesu, Laura; Di Lalla, Niccolò; Donnarumma, Immacolata; Ehlert, Steven R.; Evangelista, Yuri; Fabiani, Sergio; Ferrazzoli, Riccardo; Garcia, Javier A.; Gunji, Shuichi; Jorstad, Svetlana G.; Karas, Vladimir; Kolodziejczak, Jeffery J.; La Monaca, Fabio; Latronico, Luca; Liodakis, Ioannis; Maldera, Simone; Manfreda, Alberto; Marscher, Alan P.; Omodei, Nicola; Oppedisano, Chiara; Peirson, Abel L.; Pilia, Maura; Puccetti, Simonetta; Ramsey, Brian D.; Rankin, John; Romani, Roger W.; Soffitta, Paolo; Spandre, Gloria; Trois, Alessio; Xie, Fei; Loktev, Vladislav; Veledina, Alexandra; Ng, Chi-Yung; Sgrò, Carmelo; Svoboda, Jiri; Kravtsov, Vadim; Podgorný, Jakub; Zhang, Sixuan; Berdyugina, Svetlana V.; Sakanoi, Takeshi; Kagitani, Masato; Semena, Andrei N.; Berdyugin, Andrei; Wilms, Joern; Blinov, Dmitry; Tsygankov, Sergey; Kiehlmann, Sebastian; Mandarakas, Nikos; Draghis, Paul; Skalidis, Raphael; Thalhammer, Phillipp; O’Dell, Stephen L.
Abstract
A black hole x-ray binary (XRB) system forms when gas is stripped from a normal star and accretes onto a black hole, which heats the gas sufficiently to emit x-rays. We report a polarimetric observation of the XRB Cygnus X-1 using the Imaging X-ray Polarimetry Explorer. The electric field position angle aligns with the outflowing jet, indicating that the jet is launched from the inner x-ray–emitting region. The polarization degree is 4.01 ± 0.20% at 2 to 8 kiloelectronvolts, implying that the accretion disk is viewed closer to edge-on than the binary orbit. These observations reveal that hot x-ray–emitting plasma is spatially extended in a plane perpendicular to, not parallel to, the jet axis.