Kavli Affiliate: Herman L. Marshall
| First 5 Authors: Ivan Agudo, Ioannis Liodakis, Jorge Otero-Santos, Riccardo Middei, Alan Marscher
| Summary:
Blazars, supermassive black hole systems (SMBHs) with highly relativistic
jets aligned with the line of sight, are the most powerful long-lived emitters
of electromagnetic emission in the Universe. We report here on a radio to
gamma-ray multiwavelength campaign on the blazar BL Lacertae with unprecedented
polarimetric coverage from radio to X-ray wavelengths. The observations caught
an extraordinary event on 2023 November 10-18, when the degree of linear
polarization of optical synchrotron radiation reached a record value of 47.5%.
In stark contrast, the Imaging X-ray Polarimetry Explorer (IXPE) found that the
X-ray (Compton scattering or hadron-induced) emission was polarized at less
than 7.4% (3sigma confidence level). We argue here that this observational
result rules out a hadronic origin of the high energy emission, and strongly
favors a leptonic (Compton scattering) origin, thereby breaking the degeneracy
between hadronic and leptonic emission models for BL Lacertae and demonstrating
the power of multiwavelength polarimetry to address this question. Furthermore,
the multiwavelength flux and polarization variability, featuring an extremely
prominent rise and decay of the optical polarization degree, is interpreted for
the first time by the relaxation of a magnetic "spring" embedded in the newly
injected plasma. This suggests that the plasma jet can maintain a predominant
toroidal magnetic field component parsecs away from the central engine.
| Search Query: ArXiv Query: search_query=au:”Herman L. Marshall”&id_list=&start=0&max_results=3