Progress Toward a VLBA Movie of the Jet Collimation Region in M87

TL;DR

This paper reports progress on creating a high-cadence VLBA movie of the M87 jet's inner region to study its structure and dynamics, aiming to compare observations with theoretical models.

Contribution

It introduces a new properly sampled VLBA movie of M87's jet, with initial results showing component speeds around 0.6c, improving understanding of jet collimation and acceleration.

Findings

Measured jet speeds of about 0.6c in the inner region.

Established a 3-week frame interval for the movie.

Presented initial results from the first frame.

Abstract

With its high black hole mass, proximity, and bright jet, M87 provides the best prospect for a direct imaging study of the acceleration and collimation region of a jet. Previous VLBI observations have shown an edge brightened structure with a wide opening angle at small scales. An effort to measure component speeds in this region using existing VLBA data at 43 GHz gave tentative results of 0.25c to 0.4c but also indicated that faster sampling is needed. Here we provide a progress report on a project to make a properly sampled movie of motions in the inner jet using the VLBA at 43 GHz. A pilot project during 2006 measured speeds of about 0.6c and was used to set a frame interval of 3 weeks for the movie. The movie observations began in January 2007. Results from the pilot and from the first frame of the movie are presented. The goal of the project is to provide observations of the structure and dynamics of the jet on scales from under 100 to a few hundred Schwarzschild radii that can be compared with expectations from theoretical studies and numerical modeling.