The First VLBI Detection of a Spiral DRAGN Core

TL;DR

This paper reports the first VLBI detection of a spiral DRAGN core in galaxy 0313-192, confirming an active nucleus and providing insights into jet orientation and galaxy structure, challenging existing galaxy formation models.

Contribution

First VLBI observation of a spiral DRAGN core, confirming active nucleus and jet alignment, challenging standard galaxy formation theories.

Findings

Detected the core at multiple VLBI bands, confirming active nucleus.

Estimated jet inclination angle to be less than 72 degrees.

Found jet components aligned with larger-scale radio source.

Abstract

The existence of spiral DRAGNs challenges standard galaxy formation theories. We present the first observation of 0313$-$192, the archetypal spiral DRAGN, at VLBI resolutions. Spiral DRAGNs are Double Radio Sources Associated with Galactic Nuclei (DRAGNs) that are hosted by spiral galaxies. 0313$-$192 is an edge-on spiral galaxy that appears to host a 360 kpc double-lobed radio source. The core of this galaxy is clearly detected at L, S, and X-bands using the VLBA, signifying an ongoing active nucleus in the galaxy. This rules out the possibility that the spiral DRAGN is merely a chance alignment. The radio core has L$_{1.4\,GHz} \sim 3.0 \times 10^{23}$W Hz$^{-1}$. Radio components are detected to the South-West of the core, but there are no detections of a counterjet. Assuming a symmetric, relativistic jet, we estimate an upper limit to the inclination angle of $\theta \lesssim 72$ degrees. The VLBI-detected radio jet components are extremely well-aligned with the larger-scale radio source suggesting little to no jet disruption or interaction with the ISM of the host galaxy.