The polarization of the synchrotron radiation from a recollimated jet: application to high-energy BL Lacs
arXiv:2503.09180 · doi:10.1051/0004-6361/202554490
Abstract
Multifrequency polarimetry, recently extended to the X-ray band thanks to the Imaging X-ray Polarimetry Explorer (IXPE) satellite, is an essential tool for understanding blazar jets. High-frequency-peaked BL Lacs (HBLs) and extreme high-frequency-peaked BL Lacs (EHBLs) are especially interesting because the polarimetric properties of their synchrotron emission, extending up to the X-ray band, can be fully tracked by sensitive polarimetric measurements. We investigated the polarization properties of the synchrotron emission of these sources, starting directly from relativistic magnetohydrodynamic simulations of recollimated relativistic jets. To bridge the gap between fluid and kinetic scales, we elaborated a post-processing code based on the Lagrangian macroparticle approach, which models the spectral evolution and emission of nonthermal particles within the jet given the local fluid conditions. When comparing our results with early particle-in-cell (PIC) simulations, we find that shocks formed through jet recollimation are primarily superluminal, limiting particle acceleration in a laminar flow. However, recent PIC simulations suggest that acceleration can occur in the presence of small-scale turbulence or inhomogeneities even in a superluminal configuration. In this case, we reproduce the observed polarization chromaticity (i.e., the polarization degree increases with frequency), along with a stable polarization angle between the X-ray and optical bands. This study sheds light on the role of recollimation shocks in blazar jets and supports the energy-stratified shock model as a plausible explanation for IXPE observations.
arXiv comment18 pages, 21 figures, accepted for publication in A&A
References in corpus (52)
- SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
- Array Programming with NumPy
- PLUTO: a Numerical Code for Computational Astrophysics
- Turbulent, Extreme Multi-Zone Model for Simulating Flux and Polarization Variability in Blazars
- The PLUTO Code for Adaptive Mesh Computations in Astrophysical Fluid Dynamics
- Particle Acceleration in Relativistic Magnetized Collisionless Electron-Ion Shocks
- The Maximum Energy of Accelerated Particles in Relativistic Collisionless Shocks
- Internal shocks in the jets of radio-loud quasars
- Particle Acceleration in Relativistic Magnetized Collisionless Pair Shocks: Dependence of Shock Acceleration on Magnetic Obliquity
- Polarization of prompt GRB emission: evidence for electromagnetically-dominated outflow
- Polarization and structure of relativistic parsec-scale AGN jets
- TeV BL Lac objects at the dawn of the Fermi era
- The Piecewise Parabolic Method for Multidimensional Relativistic Fluid Dynamics
- Constraining the location of the emitting region in Fermi blazars through rapid gamma-ray variability
- Three-dimensional Relativistic MHD Simulations of Active Galactic Nuclei Jets: Magnetic Kink Instability and Fanaroff-Riley Dichotomy
- The spectrum of particles accelerated in relativistic, collisionless shocks
- Diffusive Acceleration of Particles at Oblique, Relativistic, Magnetohydrodynamic Shocks
- Simulated synchrotron emission from Pulsar Wind Nebulae
- Jet stability and the generation of superluminal and stationary components
- Polarized Blazar X-rays imply particle acceleration in shocks
- Spectral evolution of superluminal components in parsec-scale jets
- A five-wave HLL Riemann solver for relativistic MHD
- Timing Signatures of the Internal-Shock Model for Blazars
- RoboPol: The optical polarization of gamma-ray--loud and gamma-ray--quiet blazars
- Recollimation Shocks in Magnetized Relativistic Jets
- Kinetic simulations of mildly relativistic shocks I: particle acceleration in high Mach number shocks
- A Particle Module for the PLUTO code: II - Hybrid Framework for Modeling Non-thermal emission from Relativistic Magnetized flows
- Causality and stability of cosmic jets
- Simultaneous multiwavelength observations of the blazar 1ES1959+650 at a low TeV flux
- The X-ray Polarization View of Mrk~421 in an Average Flux State as Observed by the Imaging X-ray Polarimetry Explorer
- Probing Acceleration and Turbulence at Relativistic Shocks in Blazar Jets
- Linear stability analysis of magnetized relativistic jets: the nonrotating case
- Magnetic Field Amplification and Saturation in Turbulence Behind a Relativistic Shock
- The internal structure of overpressured, magnetized, relativistic jets
- Reconfinement and Loss of Stability in Jets from Active Galactic Nuclei
- Probing dissipation mechanisms in BL Lac jets through X-ray polarimetry
- Simulating the dynamics and synchrotron emission from relativistic jets II. Evolution of non-thermal electrons
- Electron-proton co-acceleration on relativistic shocks in extreme-TeV blazars
- Linear stability analysis of magnetized relativistic rotating jets
- Radiative signature of magnetic fields in internal shocks
- Recollimation shocks and radiative losses in extragalactic relativistic jets
- Systematic construction of upwind constrained transport schemes for MHD
- Physics and phenomenology of weakly magnetized, relativistic astrophysical shock waves
- Magnetic inhibition of the recollimation instability in relativistic jets
- Effect of Interacting Rarefaction Waves on Relativistically Hot Jets
- Extreme blazars: the result of unstable recollimated jets?
- A Suzaku X-Ray Study of the Particle Acceleration Processes in the Relativistic Jet of Blazar Mrk 421
- Relativistic Collisionless Shocks in Inhomogeneous Magnetized Plasmas
- Numerical simulations of MHD jets from Keplerian accretion disks I-Recollimation shocks
- Multifrequency polarimetry of High-Synchrotron Peaked blazars probes the shape of their jets
- Numerical Investigation of Instabilities in Over-pressured Magnetized Relativistic Jets
- Parsec-scale jet direction evolution in AGNs