# MOJAVE - XIV. Shapes and opening angles of AGN jets

## TL;DR

This study analyzes the shapes and opening angles of AGN jets using 15 GHz VLBA data over 20 years, revealing geometric structures, collimation behaviors, and correlations with gamma-ray emission.

## Contribution

It provides a comprehensive analysis of AGN jet geometries, opening angles, and their relation to gamma-ray properties, utilizing extensive multi-epoch VLBA observations.

## Key findings

- Jets are mostly conical on large scales, quasi-parabolic on smaller scales.
- Jets with radial acceleration are more actively collimated.
- Gamma-ray detected AGNs have wider apparent and narrower intrinsic opening angles.

## Abstract

We present 15 GHz stacked VLBA images of 373 jets associated with active galactic nuclei (AGN) having at least five observing epochs within a 20 yr time interval 1994-2015 from the MOJAVE programme and/or its precursor, the 2 cm VLBA Survey. These data are supplemented by 1.4 GHz single-epoch VLBA observations of 135 MOJAVE AGNs to probe larger scale jet structures. The typical jet geometry is found to be close to conical on scales from hundreds to thousands of parsecs, while a number of galaxies show quasi-parabolic streamlines on smaller scales. A true jet geometry in a considerable fraction of AGNs appears only after stacking epochs over several years. The jets with significant radial accelerated motion undergo more active collimation. We have analysed total intensity jet profiles transverse to the local jet ridgeline and derived both apparent and intrinsic opening angles of the flows, with medians of $21.5\deg$ and $1.3\deg$, respectively. The Fermi LAT-detected gamma-ray AGNs in our sample have, on average, wider apparent and narrower intrinsic opening angle, and smaller viewing angle than non LAT-detected AGNs. We have established a highly significant correlation between the apparent opening angle and gamma-ray luminosity, driven by Doppler beaming and projection effects.