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We report the discovery of a putative radio relic, 830 kpc in length andfound toward the outskirts of galaxy cluster Abell 1697 ($z=0.181$), using theLOFAR Two Meter Sky Survey (LoTSS) at 144 MHz. With an X-ray-inferred mass of$M_{500}^{X-ray}=2.9^{+0.8}_{-0.7}\times10^{14}~\rm{M_{\odot}}$, this placesAbell 1697 among the least massive relic hosts. The relic is also detected at325 MHz in the Westerbork Northern Sky Survey (WENSS) and at 1.4 GHz in theNRAO VLA Sky Survey (NVSS) with an average spectral index of$\alpha(144,325,1400~\rm{MHz})=-0.98\pm0.01$ and magnetic field of$B_{eq}\sim0.6~\mu$G. This relic, located in the northeast periphery of thecluster, is 300 kpc wide, exhibits a gradual spectral steepening across thewidth ($\alpha_{144 \rm{MHz}}^{1.4\rm{GHz}}(inj)=-0.70\pm0.11$ to $\alpha_{144\rm{MHz}}^{1.4\rm{GHz}}(edge)=-1.19\pm0.15$), as well as indications of aco-spatial X-ray (ROSAT) shock and the radio relic emission. The radio power ofthe relic is $P_{1.4GHz}=8.5\pm1.1\times10^{23}~\rm{W\;Hz^{-1}}$, which isfound to be in good agreement with the expected empirical correlation betweenthe radio power and Largest Linear Size (LLS) of relics. The relic is trailedby extended ($790\times550$ kpc) diffuse radio emission towards the clustercenter, that is likely an ultra-steep spectrum ($\alpha_{144\rm{MHz}}^{1.4\rm{GHz}}<-1.84$) radio source. This structure is also found tobe older by at least 190 Myrs, has a very low surface brightness of $0.3~\mu$Jyarcsec$^{-2}$ and magnetic field $B_{eq}\sim0.8~\mu$G, similar to that of aradio phoenix. Finally, we discuss the possible mechanisms responsible for therelic and the trailing diffuse radio emission, invoking re-acceleration due towake turbulence, as well as the revival of fossil electrons from an old AGNactivity by the cluster merger shocks.

Radio-relic and the diffuse emission trail discovered in a low mass galaxy cluster Abell 1697