Details

Autor(en) / Beteiligte

• Bodo, G
• Tavecchio, F
• Sironi, L

Titel

Kink-driven magnetic reconnection in relativistic jets: consequences for X-ray polarimetry of BL Lacs

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2021-02, Vol.501 (2), p.2836-2847

Ort / Verlag

Oxford University Press

Erscheinungsjahr

2021

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• ABSTRACT We investigate with relativistic MHD (magnetohydrodynamic) simulations the dissipation physics of BL Lac jets, by studying the synchrotron polarization signatures of particles accelerated by the kink instability in a magnetically dominated plasma column. The non-linear stage of the kink instability generates current sheets, where particles can be efficiently accelerated via magnetic reconnection. We identify current sheets as regions where s = Jδ/B is above some predefined threshold (where B is the field strength, J is the current density, and δ is the grid scale), and assume that the particle injection efficiency scales as ∝J2. X-ray emitting particles have short cooling times, so they only probe the field geometry of their injection sites. In contrast, particles emitting in the optical band, which we follow self-consistently as they propagate away from their injection sites while cooling, sample a larger volume, and so they may be expected to produce different polarimetric signatures. We find that the degree of polarization is roughly the same between X-ray and optical bands, because even the optical emitting particles do not travel far from the current sheet where they were injected, due to lack of sufficient kink-generated turbulence. The polarization angle shows a different temporal evolution between the two bands, due to the different regions probed by X-ray and optical emitting particles. In view of the upcoming IXPE satellite, our results can help constrain whether kink-induced reconnection (as opposed to shocks) can be the source of multiwavelength emission from BL Lacs.