15 GHz VLBI detection of the HST-1 feature in the M87 jet

TL;DR

This paper reports the first 15 GHz VLBI detection of the HST-1 feature in the M87 jet, providing insights into its properties and potential connection to TeV flares, using high-resolution radio imaging techniques.

Contribution

First 15 GHz VLBI detection of HST-1 in M87, revealing detailed radio structure and its possible link to high-energy TeV activity.

Findings

HST-1 was successfully imaged at milliarcsecond resolution.

The radio properties of HST-1 suggest a possible connection to TeV flares.

The study demonstrates the effectiveness of wide-field VLBI imaging for jet features.

Abstract

A bright feature 100 pc away from the core in the powerful jet of M 87 shows mysterious properties. Earlier radio, optical and X-ray observations have shown that this feature, labelled HST-1, is superluminal, and is possibly connected with the TeV flare detected by HESS in 2005. To examine the possible blazar-like nature of HST-1, we analyzed 2 cm VLBA data from dedicated full-track observations and the 2 cm survey/MOJAVE VLBI monitoring programs observed from 2000 to 2008. Applying wide-field imaging techniques, the HST-1 region was imaged at milliarcsecond resolutions. Here we present the first 15 GHz VLBI detection of this feature and discuss the connection between our radio findings and the TeV detection.