Is TOL 1326–379 a Prototype of γ-Ray Emitting FR0 Radio Galaxy?

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With the possible spacial association to the Fermi/LAT source 3FGL J1330.0–3818, TOL 1326–379 may be the first one that is identified as a γ-ray emitting Fanaroff–Riley type 0 radio galaxy (FR0 RG). We analyze the ∼12 yr Fermi/LAT observation data of this γ-ray source and examine its association to TOL 1326–379. We show that the γ-ray source (named as J1331.0–3818) is tentatively detected with a TS value of 28.7, 3FGL J1330.0–3818 is out of the 95% containment of J1331.0–3818, and their positions are spatially separated ∼0.°2. 4FGL J1331.3–3818 falls into the 68% containment of J1331.0–3818, suggesting that our result agrees with that reported in the Fourth Fermi LAT Source Catalog. TOL 1326–379 is out of the 95% containment of J1331.0–3818, and their positions are spatially separated ∼0.°4, indicating that the association between J1331.0–3818 and TOL 1326–379 is quite ambiguous. However, we do not find other possible potential radio or X-ray counterpart within the circle centered at J1331.0–3818 with a radius of 0.°4. The spectral energy distribution (SED) of TOL 1326–379 shows a bimodal feature as seen in the γ-ray emitting RGs. We fit the SED with the one-zone leptonic model and find that the average energy spectrum of J1331.0–3818 agrees with the model prediction. Assuming that J1331.0–3818 is an unidentified γ-ray source, we derive the upper-limit of the γ-ray flux for TOL 1326–379. It is not tight enough to exclude this possibility with the SED modeling. Based on these results, we cautiously argue that the γ-ray source J1331.0–3818 is associated with TOL 1326–379 and its jet radiation physic is similar to those γ-ray emitting RGs.