The Two-sided Jet Structures of NGC 1052 at Scales from 300 to $4 \times 10^7$ Schwarzschild Radii

TL;DR

This study examines the jet width profile of NGC 1052 across a vast range of scales, revealing symmetry between jets and a transition from cylindrical to conical structure near the black hole.

Contribution

It provides the first detailed measurement of jet width profiles from hundreds to tens of millions of Schwarzschild radii, highlighting structural transitions and symmetry in a nearby galaxy.

Findings

Jet widths are symmetric on both sides of the nucleus.

Jet structure transitions from cylindrical to conical at ~10^4 R_S.

Inner jets resemble those in 3C 84 with dense surrounding material.

Abstract

We investigated the jet width profile with distance along the jet in the nearby radio galaxy NGC 1052 at radial distances between $\sim300$ to $4 \times 10^7$ Schwarzschild Radii($R_{\rm S}$) from the central engine on both their approaching and receding jet sides. The width of jets was measured in images obtained with the VLBI Space Observatory Programme (VSOP), the Very Long Baseline Array (VLBA), and the Very Large Array (VLA). The jet-width profile of receding jets are apparently consistent with that of approaching jets throughout the measuring distance ranges, indicating symmetry at least up to the sphere of gravitational influence of the central black hole. The power-law index $a$ of the jet-width profile ($w_{\rm{jet}} \propto r^{a}$, where $w_{\rm jet}$ is the jet width, $r$ is the distance from the central engine in the unit of $R_{\rm S}$) apparently shows a transition from $a \sim 0$ to $a \sim 1$, i.e., the cylindrical-to-conical jet structures, at a distance of $\sim1\times10^{4} \ R_{\mathrm{S}}$. The cylindrical jet shape at the small distances is reminiscent of the innermost jets in 3C 84. Both the central engines of NGC 1052 and 3C 84 are surrounded by dense material, part of which is ionized and causes heavy free-free absorption.