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arXiv · 2508.14168

Unveiling blazar synchrotron emission: a multiwavelength polarimetric study of HSP and LSP populations

Sara Capecchiacci·Ioannis Liodakis·Riccardo Middei·Dawoon E. Kim·Laura Di Gesu·Ivan Agudo·Beatriz Agis-Gonzalez·Axel Arbet-Engels·Dmitry Blinov·Chien-Ting Chen·Steven R. Ehlert·Ephraim Gau·Lea Heckmann·Kun Hu·Svetlana G. Jorstad·Philip Kaaret·Pouya M. Kouch·Henric Krawczynski·Elina Lindfors·Frederic Marin·Alan P. Marscher·Ioannis Myserlis·Stephen L. O'Dell·Luigi Pacciani·David Paneque·Matteo Perri·Simonetta Puccetti·M. Lynne Saade·Fabrizio Tavecchio·Allyn F. Tennant·Efthalia Traianou·Martin C. Weisskopf·Kinwah Wu·Francisco Jose Aceituno·Giacomo Bonnoli·Victor Casanova·Gabriel Emery·Juan Escudero·Daniel Morcuende·Jorge Otero-Santos·Alfredo Sota·Vilppu Piirola·George A. Borman·Evgenia N. Kopatskaya·Elena G. Larionova·Daria A. Morozova·Ekaterina V. Shishkina·Sergey S. Savchenko·Andrey A. Vasilyev·Tatiana S. Grishina·Ivan S. Troitskiy·Alexey V. Zhovtan·Callum McCall·Helen E. Jermak·Iain A. Steele·Rumen Bachev·Anton Strigachev·Ryo Imazawa·Mahito Sasada·Yasushi Fukazawa·Koji S. Kawabata·Makoto Uemura·Tsunefumi Mizuno·Tatsuya Nakaoka·Sumie Tochihara·Takahiro Akai·Hiroshi Akitaya·Andrei V. Berdyugin·Masato Kagitani·Vadim Kravtsov·Juri Poutanen·Takeshi Sakanoi·Diego Alvarez-Ortega·Carolina Casadio·Sincheol Kang·Sang-Sung Lee·Sanghyun Kim·Whee Yeon Cheong·Hyeon-Woo Jeong·Chanwoo Song·Shan Li·Myeong-Seok Nam·Mark Gurwell·Garrett Keating·Ramprasad Rao·Emmanouil Angelakis·Alexander Kraus·Petra Benke·Lena Debbrecht·Julia Eich·Florian Eppel·Andrea Gokus·Steven Hammerich·Jonas Hessdorfer·Matthias Kadler·Dana Kirchner·Georgios Filippos Paraschos·Florian Rosch·Wladislaw Schulga
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Abstract

Polarimetric properties of blazars allow us to put constraints on the acceleration mechanisms that fuel their powerful jets. By studying the multiwavelength polarimetric behaviour of high synchrotron peaked (HSP) and low synchrotron peaked (LSP) blazars, we aim to explore differences in their emission mechanisms and magnetic field structure in the acceleration region. In this study, we take advantage of several X-ray polarisation observations of HSP by the IXPE, including four new observations of Mrk 501, and optical polarisation observations of LSP from RoboPol and many others. We find that the polarisation degree (PD) distribution of HSP in X-rays is systematically higher than in optical and mm-radio wavelengths, as reported in previous IXPE publications. The distribution of the X-ray electric vector position angles (PA) is centered around the jet axis with most of the observations consistent with zero difference within uncertainties. In fact, the distribution of the offset of the PA from the jet axis is consistent between the LSP and HSP populations (with PA measured in optical for the first, X-ray for the latter), suggesting a common magnetic field structure close to the acceleration region, in strong support of the emerging energy stratified picture of particle acceleration followed by energy loss in blazar jets.

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Sara Capecchiacci, Ioannis Liodakis, Riccardo Middei, Dawoon E. Kim, Laura Di Gesu, Ivan Agudo, Beatriz Agis-Gonzalez, Axel Arbet-Engels, Dmitry Blinov, Chien-Ting Chen, Steven R. Ehlert, Ephraim Gau, Lea Heckmann, Kun Hu, Svetlana G. Jorstad, Philip Kaaret, Pouya M. Kouch, Henric Krawczynski, Elina Lindfors, Frederic Marin, Alan P. Marscher, Ioannis Myserlis, Stephen L. O'Dell, Luigi Pacciani, David Paneque, Matteo Perri, Simonetta Puccetti, M. Lynne Saade, Fabrizio Tavecchio, Allyn F. Tennant, Efthalia Traianou, Martin C. Weisskopf, Kinwah Wu, Francisco Jose Aceituno, Giacomo Bonnoli, Victor Casanova, Gabriel Emery, Juan Escudero, Daniel Morcuende, Jorge Otero-Santos, Alfredo Sota, Vilppu Piirola, George A. Borman, Evgenia N. Kopatskaya, Elena G. Larionova, Daria A. Morozova, Ekaterina V. Shishkina, Sergey S. Savchenko, Andrey A. Vasilyev, Tatiana S. Grishina, Ivan S. Troitskiy, Alexey V. Zhovtan, Callum McCall, Helen E. Jermak, Iain A. Steele, Rumen Bachev, Anton Strigachev, Ryo Imazawa, Mahito Sasada, Yasushi Fukazawa, Koji S. Kawabata, Makoto Uemura, Tsunefumi Mizuno, Tatsuya Nakaoka, Sumie Tochihara, Takahiro Akai, Hiroshi Akitaya, Andrei V. Berdyugin, Masato Kagitani, Vadim Kravtsov, Juri Poutanen, Takeshi Sakanoi, Diego Alvarez-Ortega, Carolina Casadio, Sincheol Kang, Sang-Sung Lee, Sanghyun Kim, Whee Yeon Cheong, Hyeon-Woo Jeong, Chanwoo Song, Shan Li, Myeong-Seok Nam, Mark Gurwell, Garrett Keating, Ramprasad Rao, Emmanouil Angelakis, Alexander Kraus, Petra Benke, Lena Debbrecht, Julia Eich, Florian Eppel, Andrea Gokus, Steven Hammerich, Jonas Hessdorfer, Matthias Kadler, Dana Kirchner, Georgios Filippos Paraschos, Florian Rosch, Wladislaw Schulga. 2025-08-19. Unveiling blazar synchrotron emission: a multiwavelength polarimetric study of HSP and LSP populations. https://arxiv.org/abs/2508.14168

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