Exploring the central region of SNR 0540-69.3 with JWST I: 3D morphology

TL;DR

This study uses JWST infrared observations to reconstruct the 3D structure of supernova remnant SNR 0540-69.3, revealing detailed ejecta morphology, elemental distributions, and insights into explosion asymmetries and pulsar motion.

Contribution

First 3D morphological reconstruction of SNR 0540-69.3's inner ejecta using JWST data, highlighting asymmetries and elemental distributions in unprecedented detail.

Findings

Ejecta dominated by two fragmented lobes with similar size.

Inferred pulsar kick velocity of approximately 300 km/s.

Detection of hydrogen confirms the supernova as Type II.

Abstract

The young supernova remnant SNR 0540-69.3 in the Large Magellanic Cloud offers a detailed view of an energetic pulsar-wind nebula interacting with the surrounding ejecta. We present infrared observations of the central region of SNR 0540-69.3 obtained with the JWST NIRSpec and MRS integral field units. From the observations we reconstruct the 3D morphology of the strongest emission lines in the inner ejecta ($\lesssim$ 1000 km/s), which reveals the distribution of H I, He I, [Ne II], [Ne III], [S III], [S IV], [Fe II], and [Ni II]. The 3D morphology of most lines is dominated by two highly fragmented lobes of approximately similar size. Based on the assumption that the lobes are symmetric around the pulsar, we infer a pulsar kick velocity of ~300 km/s away from the observer. There are differences in the 3D morphologies of individual emission lines due to a combination of varying physical conditions and abundances. The detection of H I 1.8756 $\mu$m in the inner ejecta confirms the classification of the SN as a Type II and shows that hydrogen was mixed down to low velocities of < 400 km/s in the explosion. We compare the results to the Crab nebula and conclude that asymmetries originating in the explosion most likely play a major role in shaping the PWNe.