The Gamma-Ray Properties Of The FR0 Radio Galaxy TOL 1326-379

The active galaxy nucleus(AGNs)are the galaxies with violent actives in the center,which can emit powerful energies within a very small region.The radiations of AGNs cover the whole electromagnetic spectrum from radio to very high energy γ-ray band.So far,most of the detected extragalactic very-highenergy γ-ray sources are AGNs,and the gamma-rays are believed to be from the relativistic jets.FR0 radio galaxies are the subclass of AGNs,which are the type of low-luminosity compact radio sources.They are usually lacking of the distinct large-scale structures in their jet,and likely the young AGNs in the early stage of the evolution.In the nearby universe,FR0 radio galaxies are far more numerous than the typical FRI and FRII radio galaxies.At present,only a few of FR0 radio galaxies have been detected by the Fermi-LAT,the study of high-energy gammaray radiations therefore is of great significant to understand the jet properties for these radio sources.In this paper,we use Fermi-LAT observation data and other low-energy multiband data to study the γ-ray emission of FR0 radio galaxies and further to understand the physics of jet radiations.TOL 1326-379 may be the first one that is identified as a gamma-ray emitting FR0 radio galaxy.The association between 3FGL J1330.0-3818 and TOL 1326-379 was reported in the Third Fermi LAT Source Catalog,however,no gammaray counterpart for TOL 1326-379 is reported in the Fourth Fermi LAT Source Catalog.We analyze the ~12 yr Fermi-LAT observation data of this gamma-ray source and examine its association to TOL 1326-379.We show that the gammaray source(named as J1331.0-3818)is tentatively detected with a TS value of28.7.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.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.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 TOL1326-379 shows a bimodal feature as seen in the γ-ray emitting radio galaxies.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.Based on these results,we cautiously argue that the γ-ray emitting source J1331.0-3818 is associated with TOL 1326-379 and its jet radiation physic is similar to those γ-ray emitting radio galaxies.Analyzing the long-term light curves of TOL 1326-379 observed by the Catalina optical Survey telescope,we find that no obvious variation in the optical band is observed in this source,indicating that its jet activity is quiet.Recently,three more FR0 radio galaxies have been detected in the γ-ray band.We also analyzed their long-term optical light-curves,but no significant variation was presented too.And then,we intend to systematically study the correlation between optical and γ-ray radiations in AGNs using the observations of the Catalina optical Survey and ASAS-SN,together with the data of the Fermi-LAT.The sample includes 323 sources,which can be preliminarily divided into three different subclasses according to the variation characteristics,namely,optical and highenergy correlated flares,optical orphan flares,γ-ray orphan flares.This is a systematic work based on the international cooperation.I have completed the sample collation and preliminary data analysis,and the further research work is still in progress.