The Discovery of a Low-Luminosity SPIRAL DRAGN

TL;DR

This paper reports the discovery of a low-luminosity spiral DRAGN galaxy, challenging existing models by showing such sources can be less luminous and still host double-lobed radio emissions.

Contribution

It presents the first evidence of a low-luminosity spiral DRAGN, expanding the known diversity of galaxy types hosting such radio sources.

Findings

Discovered a spiral DRAGN with low radio luminosity of 1.12×10^{22} W Hz^{-1}

The host galaxy has a high black hole mass and active star formation

Suggests a previously unknown population of low-luminosity spiral DRAGNs.

Abstract

Standard galaxy formation models predict that large-scale double-lobed radio sources, known as DRAGNs, will always be hosted by elliptical galaxies. In spite of this, in recent years a small number of spiral galaxies have also been found to host such sources. These so-called spiral DRAGNs are still extremely rare, with only $\sim 5$ cases being widely accepted. Here we report on the serendipitous discovery of a new spiral DRAGN in data from the Giant Metrewave Radio Telescope (GMRT) at 322 MHz. The host galaxy, MCG+07-47-10, is a face-on late-type Sbc galaxy with distinctive spiral arms and prominent bulge suggesting a high black hole mass. Using WISE infra-red and GALEX UV data we show that this galaxy has a star formation rate of 0.16-0.75 M$_{\odot}$yr$^{-1}$, and that the radio luminosity is dominated by star-formation. We demonstrate that this spiral DRAGN has similar environmental properties to others of this class, but has a comparatively low radio luminosity of $L_{\rm 1.4GHz}$ = 1.12$\times$10$^{22}$ W Hz$^{-1}$, two orders of magnitude smaller than other known spiral DRAGNs. We suggest that this may indicate the existence of a previously unknown low-luminosity population of spiral DRAGNS.