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POLAMI Multi-Wavelength Polarization Study of AGN Jets: A Millimeter-Optical Comparison

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Bibliographic Details
Main Authors:	Casadio, C., Blinov, D., Agudo, I., Myserlis, I., Thum, C., Jorstad, S., Marscher, A., Zhang, H., Pedrosa, J. Escudero, Álvarez-Ortega, D., Weaver, Z. R., Joshi, M., McCall, C., Jermak, H., Steele, I. A., Borman, G. A., Grishina, T. S., Larionova, E. G., Morozova, D. A., Savchenko, S. S., Troitskiy, I. S., Troitskaya, Y. V., Vasilyev, A. A.
Format:	Preprint
Published:	2026
Subjects:	High Energy Astrophysical Phenomena Cosmology and Nongalactic Astrophysics
Online Access:	Acceder al recurso
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_version_	1866915734064463872
author	Casadio, C. Blinov, D. Agudo, I. Myserlis, I. Thum, C. Jorstad, S. Marscher, A. Zhang, H. Pedrosa, J. Escudero Álvarez-Ortega, D. Weaver, Z. R. Joshi, M. McCall, C. Jermak, H. Steele, I. A. Borman, G. A. Grishina, T. S. Larionova, E. G. Morozova, D. A. Savchenko, S. S. Troitskiy, I. S. Troitskaya, Y. V. Vasilyev, A. A.
author_facet	Casadio, C. Blinov, D. Agudo, I. Myserlis, I. Thum, C. Jorstad, S. Marscher, A. Zhang, H. Pedrosa, J. Escudero Álvarez-Ortega, D. Weaver, Z. R. Joshi, M. McCall, C. Jermak, H. Steele, I. A. Borman, G. A. Grishina, T. S. Larionova, E. G. Morozova, D. A. Savchenko, S. S. Troitskiy, I. S. Troitskaya, Y. V. Vasilyev, A. A.
contents	Millimeter-band polarimetry offers a powerful probe of AGN jets, accessing regions less affected by opacity and Faraday rotation than at longer radio wavelengths. As part of the POLAMI program, we have conducted 14 years of 1 mm and 3 mm polarization monitoring of a sample of gamma-ray-bright blazars with the IRAM 30-m telescope, complemented here with long-term optical polarimetric observations from multiple facilities. We aim to test whether current models of parsec-scale jet physics are consistent with observed multi-band polarization behavior. Using a Bayesian framework, we derive intrinsic mean flux densities and modulation indices for total flux and fractional polarization, and characterize EVPA variability using circular statistics. We then examine how these quantities reflecting variability properties across millimeter and optical bands relate to synchrotron peak frequency, jet orientation, and radio/gamma-ray luminosities. BL Lac objects exhibit, on average, higher fractional polarization and lower EVPA variability than FSRQs at all wavelengths. Fractional polarization increases with frequency, consistent with increasingly ordered magnetic fields at shorter wavelengths. BL Lacs also show more frequent alignment of EVPAs between optical and millimeter bands, whereas FSRQs display weaker coherence. EVPA variability correlates positively with radio and gamma-ray luminosities and negatively with synchrotron peak frequency, most strongly in the optical. We further find a positive correlation between EVPA spread and fractional polarization variability, suggesting a direct link between magnetic-field structure and polarization dynamics.
format	Preprint
id	arxiv_https___arxiv_org_abs_2601_10798
institution	arXiv
publishDate	2026
record_format	arxiv
spellingShingle	POLAMI Multi-Wavelength Polarization Study of AGN Jets: A Millimeter-Optical Comparison Casadio, C. Blinov, D. Agudo, I. Myserlis, I. Thum, C. Jorstad, S. Marscher, A. Zhang, H. Pedrosa, J. Escudero Álvarez-Ortega, D. Weaver, Z. R. Joshi, M. McCall, C. Jermak, H. Steele, I. A. Borman, G. A. Grishina, T. S. Larionova, E. G. Morozova, D. A. Savchenko, S. S. Troitskiy, I. S. Troitskaya, Y. V. Vasilyev, A. A. High Energy Astrophysical Phenomena Cosmology and Nongalactic Astrophysics Millimeter-band polarimetry offers a powerful probe of AGN jets, accessing regions less affected by opacity and Faraday rotation than at longer radio wavelengths. As part of the POLAMI program, we have conducted 14 years of 1 mm and 3 mm polarization monitoring of a sample of gamma-ray-bright blazars with the IRAM 30-m telescope, complemented here with long-term optical polarimetric observations from multiple facilities. We aim to test whether current models of parsec-scale jet physics are consistent with observed multi-band polarization behavior. Using a Bayesian framework, we derive intrinsic mean flux densities and modulation indices for total flux and fractional polarization, and characterize EVPA variability using circular statistics. We then examine how these quantities reflecting variability properties across millimeter and optical bands relate to synchrotron peak frequency, jet orientation, and radio/gamma-ray luminosities. BL Lac objects exhibit, on average, higher fractional polarization and lower EVPA variability than FSRQs at all wavelengths. Fractional polarization increases with frequency, consistent with increasingly ordered magnetic fields at shorter wavelengths. BL Lacs also show more frequent alignment of EVPAs between optical and millimeter bands, whereas FSRQs display weaker coherence. EVPA variability correlates positively with radio and gamma-ray luminosities and negatively with synchrotron peak frequency, most strongly in the optical. We further find a positive correlation between EVPA spread and fractional polarization variability, suggesting a direct link between magnetic-field structure and polarization dynamics.
title	POLAMI Multi-Wavelength Polarization Study of AGN Jets: A Millimeter-Optical Comparison
topic	High Energy Astrophysical Phenomena Cosmology and Nongalactic Astrophysics
url	https://arxiv.org/abs/2601.10798