Clumps and rings of ejecta in SNR 0540-69.3 as seen in 3D

Abstract

The distribution of ejecta in young supernova remnants offers a powerful observational probe of their explosions and progenitors. Here we present a 3D reconstruction of the ejecta in SNR 0540-69.3, which is an O-rich remnant with a pulsar wind nebula located in the LMC. We use observations from VLT/MUSE to study Hβ, [O III] λλ4959, 5007, Hα, [S II] λλ6717, 6731, [Ar III] λ7136 and [S III] λ9069. This is complemented by 2D spectra from VLT/X-shooter, which also cover [O II] λλ3726, 3729 and [Fe II] λ12567. We identify three main emission components: (i) Clumpy rings in the inner nebula ( 1000 km s −1 ) with similar morphologies in all lines; (ii) Faint extended [O III] emission dominated by an irregular ring-like structure with radius ∼ 1600 km s −1 and inclination ∼ 40 • , but with maximal velocities reaching ∼ 3000 km s −1 ; and (iii) A blob of Hα and Hβ located southeast of the pulsar at velocities ∼ 1500 − 3500 km s −1 . We analyze the geometry using a clump-finding algorithm and use the clumps in the [O III] ring to estimate an age of 1146 ± 116 years. The observations favor an interpretation of the [O III] ring as ejecta, while the origin of the H-blob is more uncertain. An alternative explanation is that it is the blown-off envelope of a binary companion. From the detection of Balmer lines in the innermost ejecta we confirm that SNR 0540 was a Type II supernova and that hydrogen was mixed down to low velocities in the explosion.

Imprints of the jittering jets explosion mechanism in the morphology of the supernova remnant SNR 0540-69.3

“…From that I find the total kick velocity under the assumptions of this study to be v k 386 km s −1 . However, the pulsarejecta relative velocity might be smaller because the ejecta has a general red-shifted velocity relative to the local ISM in the LMC (Larsson et al 2021). This might be a result from asymmetrical explosion (Larsson et al 2021), and therefore the value of v k,z = −306 km s −1 might be an overestimate.…”

“…4. DISCUSSION AND SUMMARY I examined the images and velocity maps of SNR 0540-69.3 that Larsson et al (2021) present in a recent study. I defined a faint strip (upper left panel of Fig.…”

“…I termed this axis the main jet-axis. Larsson et al (2021) obtain the velocity maps, which I present here in Fig. 3, in a plane perpendicular to the plane of the sky by a slit that the two dashed lines in two panels of Fig.…”

“…From the location of the pulsar relative to the main jet axis and the age of 1100 yr for SNR 0540-69.3 that Larsson et al (2021) estimate, I estimated the transverse (projected on the plane of the sky) pulsar natal kick velocity to be v k,T 235 km s −1 at α 47 • to the direction of the main jet-axis (red double-lined arrow on the right panel of Fig. 2).…”

“…In the present study I examine the newly published high-quality observations and analysis of SNR 0540-69.3 by Larsson et al (2021) to argue that there is a pointsymmetric structure as expected in the jittering jets explosion mechanism (section 2). X-ray observations (e.g.…”