MeerKAT discovery of a double radio relic and odd radio circle: connecting cluster and galaxy merger shocks

We present the serendipitous discovery of (1) a large double radio relic associated with the galaxy cluster PSZ2 G277.93 + 12.34 and (2) a new odd radio circle, ORC J1027-4422, both found in the same deep MeerKAT 1.3 GHz wide-band radio continuum image. The angular separation of the two arc-shaped cluster relics is similar to 16 arcmin or similar to 2.6 Mpc for a cluster redshift of z approximate to 0.158. The thin southern relic, which shows several ridges/shocks including one possibly moving inwards, has a linear extent of similar to 1.64 Mpc. In contrast, the northern relic is about twice as wide, twice as bright, but only has a largest linear size of similar to 0.66 Mpc. Complementary SRG/eROSITA X-ray images reveal extended emission from hot intracluster gas between the two relics and around the narrow-angle tail (NAT) radio galaxy PMN J1033-4335 (z approximate to 0.153) located just east of the northern relic. The radio morphologies of the NAT galaxy and the northern relic, which are also detected with the Australian Square Kilometer Array Pathfinder (ASKAP) at 888 MHz, suggest both are moving in the same outward direction. The discovery of ORC J1027-4422 in a different part of the same MeerKAT image makes it the fourth known single ORC. It has a diameter of similar to 90 arcsec corresponding to 400 kpc at a tentative redshift of z approximate to 0.3 and remains undetected in X-ray emission. Supported by simulations, we discuss similarities between outward moving galaxy and cluster merger shocks as the formation mechanisms for ORCs and radio relics, respectively.