Identifying jittering-jet-shaped ejecta in the Cygnus Loop supernova remnant

TL;DR

This study identifies a point-symmetrical, jet-shaped morphology in the Cygnus Loop supernova remnant, supporting the jittering jets explosion mechanism as the primary cause of core-collapse supernovae.

Contribution

It provides observational evidence of jet-shaped structures consistent with the jittering jets explosion model in a supernova remnant.

Findings

Identification of a point-symmetrical jet-shaped morphology in the Cygnus Loop.

Detection of structures consistent with multiple pairs of jets in various emission bands.

Support for the jittering jets explosion mechanism as the main CCSNe explosion process.

Abstract

Analyzing images of the Cygnus Loop, a core-collapse supernova (CCSN) remnant, in different emission bands, we identify a point-symmetrical morphology composed of three symmetry axes that we attribute to shaping by three pairs of jets. The main jet axis has an elongated S shape, appearing as a faint narrow zone in visible and UV. We term it the S-shaped hose, and the structure of three symmetry lines, the point-symmetric wind rose. The two other lines connect a protrusion (an ear or a bulge) with a hole on the opposite side of the center (a nozzle or a cavity), structures that we identify in the X-ray, UV, visible, IR, and/or radio images. There is a well-known blowout at the southern end of the S-shaped hose, and we identify a possible opposite blowout at the northern end of the S-shaped hose. The point-symmetrical morphology of the Cygnus Loop is according to the expectation of the jittering jets explosion mechanism (JJEM) of CCSNe, where several to few tens of pairs of jets with stochastically varying directions explode the star. The three pairs of jets that shaped the wind-rose structure of the Cygnus Loop are the last energetic pairs of this series of jets. Our study further supports the JJEM as the main explosion mechanism of CCSNe.