The Curious Case of the “Heartworm” Nebula

Abstract

The curious Galactic features near G357.2−0.2 were observed with the MeerKAT radio interferometer array in the UHF and L bands (0.56–1.68 GHz). There are two possibly related features: a newly identified faint heart-shaped partial shell (the “heart”), and a series of previously known but now much better imaged narrow, curved features (the “worm”) interior to the heart. Polarized emission suggests that much of the emission is nonthermal and is embedded in a dense plasma. The filaments of the worm appear to be magnetic structures powered by embedded knots that are sites of particle acceleration. The morphology of the worm broadly resembles some known pulsar wind nebulae (PWNe) but there is no known pulsar or PWN which could be powering this structure. We also present eROSITA observations of the field; no part of the nebula is detected in X-rays, but the current limits do not preclude the existence of a pulsar/PWN of intermediate spin-down luminosity.

A unique, ring-like radio source with quadrilateral structure detected with machine learning

“…Already, the SKA precursor telescopes, such as MeerKAT (Jonas & MeerKAT Team 2016), ASKAP (Hotan et al 2021) and LOFAR (van Haarlem et al 2013), are producing datasets of remarkable size and richness. These datasets have proven to be a treasure trove for scientific discoveries, including Odd Radio Circles (ORCs Norris et al 2021), the "heartworm" nebula (Cotton et al 2022), a giant 5-Mpc radio galaxy (Oei et al 2022) and many others. Even older large surveys, such as FIRST (Becker et al 1995), have continued to reveal interesting new sources through intensive visible inspection in projects such as Radio Galaxy Zoo (Banfield et al 2015(Banfield et al , 2016.…”