A closer look at the flaring feature in the M87 jet

TL;DR

This study analyzes 2 cm VLBI data of the M87 jet to investigate a bright feature's structure and motion, finding it extended with a steep spectrum and no rapid movement, thus challenging a blazar interpretation.

Contribution

It provides detailed VLBI observations of a jet feature in M87 over nine years, clarifying its structure and motion, and refuting a blazar scenario.

Findings

Feature is extended with a steep spectrum.

No compact or rapidly moving components detected.

Results do not support a blazar scenario.

Abstract

The radio-loud active galactic nucleus in M 87 hosts a powerful jet fueled by a super-massive black hole in its center. A bright feature 80 pc away from the M 87 core has been reported to show superluminal motions, and possibly to be connected with a TeV flare observed around 2005. To complement these studies and to understand the nature of this feature, we analyzed 2 cm VLBI data from 15 observing runs between 2000 and 2009. This feature is successfully detected at the milli-Jansky level from 2003 to 2007. Our detections show that its milli-arcsecond structure appears to be extended with a steep spectrum, and no compact or rapidly moving features are observed. Our results do not favor a blazar scenario for this feature.