Speaker
Description
Blazars, the jetted AGN with their axes closely aligned to our line of sight, comprise one of the most energetic, long-lived phenomena, dominate the gamma-ray sky and are possible neutrino emitters. The low-energy part of their SEDs is understood as incoherent synchrotron emission from their jets, which spans from radio to optical, UV or even X-rays and is both linearly and circularly polarized. On top of their persistent broadband emission, blazar jets often show pronounced variability across the electromagnetic spectrum with timescales from days/months down to minutes.
Here, I will demonstrate our efforts to capture the complex phenomenology of blazar jets through dedicated multi-wavelength polarization monitoring programs using several large (sub-)mm and radio facilities – such as POLAMI, SMAPOL, BEAM-ME and QUIVER – and in coordination with other multi-wavelength campaigns, including IXPE or MAGIC. Our observations, which cover two decades of frequency (2.6—230 GHz), follow the flux density and polarization variations of blazars with high cadence to constrain the jet physical conditions and dynamics. I will present the various challenges of high-precision, circular and linear polarimetry, the unique benefits of long monitoring programs to keep track of the efficiency and overall quality of the instrument and discuss future prospects for deep, polarimetric observations of large, statistically robust samples using high sensitivity and wide FoV facilities, such as AtLAST.