Intrinsic Origin Of Extreme-Scale Rotation Of Quasar Polarization Vectors

摘要

Extreme-scale alignment of quasar optical polarization vectors atcosmological scales ($z\le 2$) is also characterized by the rotation of meanposition angle $\chi$ with $\Delta \chi \approx 30^{\circ}$ per 1 Gpc. Forobserving interval of $z$ the total rotation angle acquires the value $\sim90^{\circ}$. We suggest the possible explanation of the half of this rotationas a consequence of physical transformation of initially vertical magneticfield ${\bf B}_{\|}$, directed along the normal ${\bf N}$ to the surface ofaccretion disk, into the horizontal (perpendicular to ${\bf N}$) one. We foundasymptotical analytical expressions for axially averaged polarization degree$p$ and mean position angle $\chi$ for various types of magnetized accretiondisks. We found also that during the evolution can be realized the case$B_{\bot}\approx B_{\|}$ where position angle $\chi$ rotates from $45^{\circ}$to zero. This rotation may occur during fairly great cosmological time(corresponding to $\Delta z\sim 1-2$). The part of rotation $\sim \Delta \chi\approx 45^{\circ}$ can be explained by a mechanism of alignment ofpolarization vectors, say distribution of the part of quasars as a spiral inthe cosmic space with slow variation of rotation axis of correspondingaccretion disks. Both mechanisms are mutually related one with another.