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X-Ray Polarization Observations of BL Lacertae

2022; IOP Publishing; Volume: 942; Issue: 1 Linguagem: Inglês

10.3847/2041-8213/aca281

2041-8213

R. Middei, Ioannis Liodakis, M. Perri, Simonetta Puccetti, E. Cavazzuti, Laura Di Gesu, Steven R. Ehlert, G. Madejski, Alan P. Marscher, Herman L. Marshall, Fabio Muleri, Michela Negro, Svetlana G. Jorstad, Beatriz Agı́s-González, I. Agudo, G. Bonnoli, M. Bernardos, V. Casanova, Maya García‐Comas, C. Husillos, Alessandro Marchini, A. Sota, Pouya M. Kouch, E. Lindfors, Г. А. Борман, E. N. Kopatskaya, Е. Г. Ларионова, D. A. Morozova, С. С. Савченко, A. A. Vasilyev, А. В. Жовтан, C. Casadio, Juan Escudero, I. Myserlis, Antonio Hales, Seiji Kameno, R. Kneißl, Hugo Messias, Hiroshi Nagai, D. Blinov, Ioakeim G. Bourbah, S. Kiehlmann, Evangelos Kontopodis, N. Mandarakas, Stylianos Romanopoulos, R. Skalidis, Anna Vervelaki, J. Masiero, Dimitri Mawet, Maxwell A. Millar‐Blanchaer, G. V. Panopoulou, Samaporn Tinyanont, A. Berdyugin, Masato Kagitani, Vadim Kravtsov, Takeshi Sakanoi, Ryo Imazawa, Mahito Sasada, Y. Fukazawa, Koji S. Kawabata, Makoto Uemura, Tsunefumi Mizuno, Tatsuya Nakaoka, Hiroshi Akitaya, Mark Gurwell, Ramprasad Rao, Niccolò Di Lalla, N. Cibrario, I. Donnarumma, Dawoon E. Kim, N. Omodei, L. Pacciani, Juri Poutanen, F. Tavecchio, L. A. Antonelli, Matteo Bachetti, L. Baldini, W. H. Baumgartner, R. Bellazzini, S. Bianchi, Stephen D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, Fiamma Capitanio, Simone Castellano, S. Ciprini, E. Costa, Alessandra De Rosa, E. Del Monte, Alessandro Di Marco, Victor Doroshenko, Michal Dovčiak, Teruaki Enoto, Y. Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. García, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, W. Iwakiri, V. Karas, Takao Kitaguchi, Jeffery J. Kolodziejczak, H. Krawczynski, Fabio La Monaca, L. Latronico, S. Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, F. Massaro, G. Matt, Ikuyuki Mitsuishi, C.‐Y. Ng, Stephen L. O’Dell, C. Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, M. Pesce-Rollins, Pierre-Olivier Petrucci, M. Pilia, Andrea Possenti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Roger W. Romani, C. Sgrò, Patrick Slane, P. Soffitta, G. Spandre, Toru Tamagawa, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, A. Trois, Sergey S. Tsygankov, R. Turolla, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, Fei Xie, Silvia Zane,

Astrophysical Phenomena and Observations

Abstract Blazars are a class of jet-dominated active galactic nuclei with a typical double-humped spectral energy distribution. It is of common consensus that the synchrotron emission is responsible for the low frequency peak, while the origin of the high frequency hump is still debated. The analysis of X-rays and their polarization can provide a valuable tool to understand the physical mechanisms responsible for the origin of high-energy emission of blazars. We report the first observations of BL Lacertae (BL Lac) performed with the Imaging X-ray Polarimetry Explorer, from which an upper limit to the polarization degree Π X < 12.6% was found in the 2–8 keV band. We contemporaneously measured the polarization in radio, infrared, and optical wavelengths. Our multiwavelength polarization analysis disfavors a significant contribution of proton-synchrotron radiation to the X-ray emission at these epochs. Instead, it supports a leptonic origin for the X-ray emission in BL Lac.