6533b85efe1ef96bd12bf386

RESEARCH PRODUCT

ALMA full polarization observations of PKS1830-211 during its record-breaking flare of 2019

José L. GómezAlan P. MarscherSebastien MullerIvan Marti-vidalAlejandro MusI. Agudo

subject

Astrophysics::High Energy Astrophysical PhenomenaGamma rays: generalgeneral [Gamma rays]FOS: Physical sciencesQuasars: individual: PKS1830-211AstrophysicsAstrophysics::Cosmology and Extragalactic Astrophysics01 natural scienceslaw.inventionlawPolarization0103 physical sciencesindividual: PKS1830-211 [Quasars]Blazar010303 astronomy & astrophysicsPhysicsHigh Energy Astrophysical Phenomena (astro-ph.HE)010308 nuclear & particles physicsAstronomy and AstrophysicsQuasarAtacama Large Millimeter ArrayPolarization (waves)Position angleFractional polarizationSpace and Planetary ScienceAstrophysics - High Energy Astrophysical PhenomenaFlare

description

We report Atacama Large Millimeter Array (ALMA) Band 6 full-polarization observations of the lensed blazar PKS 1830-211 during its record-breaking radio and gamma-ray flare in the spring of 2019. The observations were taken close to the peak of the gamma activity and show a clear difference in polarization state between the two time-delayed images. The leading image has a fractional polarization about three times lower than the trailing image, implying that significant depolarization occurred during the flare. In addition, we observe clear intra-hour variability of the polarization properties between the two lensed images, with a quasi-linear increase in the differential electric-vector position angle at a rate of about two degrees per hour, associated with changes in the relative fractional polarization of ∼10%. This variability, combined with the lower polarization close to the peak of gamma activity, is in agreement with models of magnetic turbulence to explain polarization variability in blazar jets. Finally, the comparison of results from the full and differential polarization analysis confirms that the differential polarization technique (Martí-Vidal et al. 2016, A&A, 593, A61) can provide useful information on the polarization state of sources like gravitationally lensed radio-loud quasars. © ESO 2020.

https://dx.doi.org/10.48550/arxiv.2006.06044