Analysis of Jet Dynamics and Collimation Characteristics of 0241+622 on Parsec Scales

TL;DR

This study analyzes the jet structure and dynamics of 0241+622 on parsec scales, revealing parabolic to conical shape transitions, acceleration, and environmental influences on collimation, using multi-epoch VLBA data.

Contribution

It provides detailed measurements of jet shape, velocity, and environmental effects, including the first estimation of the Bondi radius impact on jet collimation for this source.

Findings

Jet exhibits parabolic shape from 0.12 to 6.1 mas

Jet transitions to conical shape beyond 18 mas

Jet acceleration observed within 3.14 mas from the core

Abstract

We conducted a detailed analysis of the jet structure and dynamics of the source 0241+622 on milliarcsecond (mas) scales. We stacked images from multiple epochs to better recover the crosssection of the jet. By analyzing the relationship between jet width and distance, we observed that the jet exhibits a parabolic shape from the core, spanning a region from 0.12 to 6.1 mas. This structure suggests the acceleration and collimation processes of the jet. Beyond 18 mas from the core, the jet adopts a conical shape, and the expansion speed of the jet becomes faster within the range from 4500 to 6500 mas. We obtained the core shift of this source using five pairs of data from VLBA at 1.6 GHz to 43 GHz. Based on previous studies, through proper motion analysis of the jet components, we estimated the angle between the jet and the line of sight to be approximately 65.7{\deg}, so 1 mas corresponds to 0.95 pc (de-projected distance). We then obtained the velocity field of the source within 3.14 mas from the central black hole and found that the jet exhibits accelerated motion within this range. At approximately 6.1 mas from the core, we observed that the jet width begins to decrease, which we identified as possibly corresponding to the Bondi radius of this source. The reduction in jet width may be related to changes in the external environmental pressure, particularly within the Bondi radius, indicating that the jet dynamics and collimation characteristics are strongly influenced by the surrounding medium conditions.