X-Ray Polarization of the BL Lacertae Type Blazar 1ES 0229+200
Steven R. Ehlert, Ioannis Liodakis, R. Middei, Alan P. Marscher, F. Tavecchio, I. Agudo, Pouya M. Kouch, E. Lindfors, K. Nilsson, I. Myserlis, Mark Gurwell, Ramprasad Rao, F. J. Aceituno, G. Bonnoli, V. Casanova, Beatriz Agı́s-González, Juan Escudero, C. Husillos, Jorge Otero-Santos, A. Sota, E. Angelakis, A. Kraus, Garrett K. Keating, 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, E. Cavazzuti, Chien‐Ting Chen, S. Ciprini, E. Costa, Alessandra De Rosa, E. Del Monte, Laura Di Gesu, Niccolò Di Lalla, Alessandro Di Marco, I. Donnarumma, Victor Doroshenko, Michal Dovčiak, Teruaki Enoto, Y. Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. García, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, W. Iwakiri, Svetlana G. Jorstad, P. Kaaret, V. Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, H. Krawczynski, Fabio La Monaca, L. Latronico, S. Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Herman L. Marshall, F. Massaro, G. Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, Michela Negro, C.‐Y. Ng, Stephen L. O’Dell, N. Omodei, C. Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, M. Perri, M. Pesce-Rollins, Pierre-Olivier Petrucci, M. Pilia, Andrea Possenti, Juri Poutanen, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, O. J. Roberts, Roger W. Romani, C. Sgró, Patrick Slane, P. Soffitta, G. Spandre, Douglas A. Swartz
Abstract
Abstract We present polarization measurements in the 2–8 keV band from blazar 1ES 0229+200, the first extreme high synchrotron peaked source to be observed by the Imaging X-ray Polarimetry Explorer (IXPE). Combining two exposures separated by about two weeks, we find the degree of polarization to be Π X = 17.9% ± 2.8% at an electric-vector position angle ψ X = 25.°0 ± 4.°6 using a spectro-polarimetric fit from joint IXPE and XMM-Newton observations. There is no evidence for the polarization degree or angle varying significantly with energy or time on both short timescales (hours) or longer timescales (days). The contemporaneous polarization degree at optical wavelengths was >7× lower, making 1ES 0229+200 the most strongly chromatic blazar yet observed. This high X-ray polarization compared to the optical provides further support that X-ray emission in high-peaked blazars originates in shock-accelerated, energy-stratified electron populations, but is in tension with many recent modeling efforts attempting to reproduce the spectral energy distribution of 1ES 0229+200, which attribute the extremely high energy synchrotron and Compton peaks to Fermi acceleration in the vicinity of strongly turbulent magnetic fields.