Testing particle acceleration in blazar jets with continuous high-cadence optical polarization observations

¹ Institute of Astrophysics, Foundation for Research and Technology-Hellas, 70013 Heraklion, Greece
² NASA Marshall Space Flight Center, Huntsville, AL, 35812 USA
³ Department of Physics, University of Crete, 70013 Heraklion, Greece
⁴ Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA, 02215 USA
⁵ University of Maryland Baltimore, County Baltimore, MD, 21250 USA
⁶ NASA Goddard Space Flight Center Greenbelt, MD, 20771 USA
⁷ Saint Petersburg State University, 7/9 Universitetskaya nab., St., Petersburg, 199034 Russia
⁸ Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
⁹ Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P. 70-264, CDMX 04510, México, Ensenada 22800, Baja California, Mexico
¹⁰ Department of Physics and Astronomy, University of Turku, 20014 Finland
¹¹ INAF Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy
¹² Institute of Astronomy, National Central University, Taoyuan, 32001 Taiwan
¹³ Department of Physics, Graduate School of Advanced Science and Engineering, Hiroshima University Kagamiyama, 1-3-1 Higashi-Hiroshima, Hiroshima, 739-8526 Japan
¹⁴ Astrophysics Research Institute, Liverpool John Moores University, Liverpool Science Park IC2, 146 Brownlow Hill, Liverpool, L3 5RF UK
¹⁵ Finnish Centre for Astronomy with ESO (FINCA), FI-20014 University of Turku, Finland
¹⁶ Facultad de Ciencias, Universidad Autónoma de Baja California, Campus El Sauzal, 22800 Ensenada, Baja California, Mexico
¹⁷ Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital, 263002 India
¹⁸ Center for Basic Sciences, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh, 492010 India
¹⁹ Department of Applied Physics/Physics, M.J.P. Rohilkhand University, Bareilly, Uttar Pradesh, 24300 India
²⁰ Institute of Innovative Research (IIR), Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
²¹ Pulkovo Observatory, St.Petersburg, 196140 Russia
²² Special Astrophysical Observatory of Russian Academy of Sciences, Nizhnij Arkhyz, Karachai-Cherkessian Republic, 369167 Russia
²³ Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Santiago Región Metropolitana, 8370191 Chile
²⁴ Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson AZ, 85721-0065 USA
²⁵ Hiroshima Astrophysical Science Center, Hiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526 Japan
²⁶ Core Research for Energetic Universe (Core-U), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526 Japan
²⁷ Centre for Astrophysics Research, University of Hertfordshire, Hatfield, AL10 9AB UK
²⁸ School of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH UK

Received: 8 June 2024
Accepted: 21 June 2024

Abstract

Variability can be the pathway to understanding the physical processes in astrophysical jets. However, the high-cadence observations required to test particle acceleration models are still missing. Here we report on the first attempt to produce continuous, > 24 hour polarization light curves of blazars using telescopes distributed across the globe, following the rotation of the Earth, to avoid the rising Sun. Our campaign involved 16 telescopes in Asia, Europe, and North America. We observed BL Lacertae and CGRaBS J0211+1051 for a combined 685 telescope hours. We find large variations in the polarization degree and angle for both sources on sub-hour timescales as well as a ∼180° rotation of the polarization angle in CGRaBS J0211+1051 in less than two days. We compared our high-cadence observations to particle-in-cell magnetic reconnection and turbulent plasma simulations. We find that although the state-of-the-art simulation frameworks can produce a large fraction of the polarization properties, they do not account for the entirety of the observed polarization behavior in blazar jets.