Testing particle acceleration models for BL LAC jets with the Imaging X-ray Polarimetry Explorer

Abstract

To determine if the recently launched Imaging X-ray Polarimetry Explorer (IXPE) can follow the polarization variations induced by different particle acceleration mechanisms in blazars jets we simulate observations of a high synchrotron peak (HSP) blazar variable in polarization degree and angle according to the theoretical predictions of Tavecchio et al., 2020 (shock acceleration model), Bodo et al., 2021 (magnetic reconnection model) and Marscher \& Jorstad, 2021 (Turbulent Extreme Multi-Zone Model). We use the Monte Carlo tool ixpeobssim to create realistic IXPE data products. We create simulated light-curves of polarization degree and angle by time-slicing the simulated data into arbitrary short time bins. We use a ${\chi }^2$ test to assess the performance of the observations in detecting the time variability of the polarization properties. A series of 10 ks long observations permits IXPE to follow the time variability of the polarization degree in the case of the shock acceleration model. In the case of the magnetic reconnection model, the nominal injected model provides the best fit of the simulated IXPE data for time bins of 5-10 ks, depending on the tested flux level. For the TEMZ model, shorter time slices of 0.5 ks are needed for obtaining a formally good fit of the simulated IXPE data with the injected model. On the other hand, we find that a fit with a constant model provides a ${\chi }^2$ lower than the fit with the nominal injected model when using time slices of 20 ks, 60/70 ks, and 5 ks for the case of the shock acceleration, magnetic reconnection and TEMZ model, respectively. We conclude that, provided that the statistics of the observation allows slicing of the data in adequately short time bins, IXPE observations of an HSP blazar at a typical flux level can detect the time variability predicted by popular models for particle acceleration in jets.

accepted for publication in Astronomy&Astrophysics

References in corpus (5)

• Magnetic acceleration of relativistic AGN jets
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• Analyzing the Data from X-ray Polarimeters with Stokes Parameters
• Probing shock acceleration in BL Lac jets through X-ray polarimetry: the time-dependent view
• Prospects for the polarimetric mapping of the Sgr A molecular cloud complex with IXPE

Cited by in corpus (11)

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• High optical to X-ray polarization ratio reveals Compton scattering in BL Lacertae's jet
• IXPE Observation of the Low-Synchrotron Peaked Blazar S4 0954+65 During An Optical-X-ray Flare
• Insights from the first flaring activity of a high-synchrotron-peaked blazar with X-ray polarization and VHE gamma rays
• VHE $\gamma$-ray observations of bright BL Lacs with the Large-Sized Telescope prototype (LST-1) of the CTAO
• Radiative signatures of electron-ion shocks in BL Lac type objects
• Science with a large field-of-view polarization survey: The Large Array Survey Telescope Polarization Node (LAST-P)