Discovery of a FR0 radio galaxy emitting at $\gamma$-ray energies

TL;DR

This paper reports the first evidence that FR0 radio galaxies, which are common but poorly understood, can emit gamma rays, demonstrated through the association of the Fermi source 3FGLJ1330.0-3818 with the FR0 galaxy Tol1326-379.

Contribution

It provides the first observational evidence of gamma-ray emission from an FR0 radio galaxy, expanding understanding of their energetic capabilities.

Findings

FR0 galaxy Tol1326-379 emits gamma rays with a luminosity of ~2×10^{42} erg/s.

The gamma-ray spectrum of Tol1326-379 is steeper than typical FRIs.

This emission suggests FR0s can be gamma-ray sources, challenging previous assumptions.

Abstract

We present supporting evidence for the first association of a Fermi source, 3FGLJ1330.0-3818, with the FR0 radio galaxy Tol1326-379. FR0s represent the majority of the local radio loud AGN population but their nature is still unclear. They share the same properties of FRIs from the point of view of the nuclear and host properties, but they show a large deficit of extended radio emission. Here we show that FR0s can emit photons at very high energies. Tol1326-379 has a GeV luminosity of $L_{>1~{\rm GeV}} \sim 2\times10^{42}$ erg s$^{-1}$, typical of FRIs, but with a steeper $\gamma$-ray spectrum ($\Gamma=2.78\pm 0.14$). This could be related to the intrinsic jet properties but also to a different viewing angle.