3D Kinematic Reconstruction of the Crab Nebula That Includes the Northern Ejecta `Jet'

Abstract

We present new detailed three-dimensional kinematic reconstructions of the Crab Nebula created from hyperspectral cubes obtained with the SITELLE instrument mounted on the Canada--France--Hawaii Telescope. Our data cubes span a wavelength range from 3600Å to 7000Å, covering major emission lines including [O II] $\lambda \lambda$3726, 3729, H$\beta$, [O III] $\lambda \lambda$4959, 5007, [N II] $\lambda$5755, He I $\lambda$5876, [N II] $\lambda \lambda$6548, 6584, [S II] $\lambda \lambda$6717, 6731, and H$\alpha$. The field of view encompasses the ``chimney" or ``jet," a 45-arcsec-wide funnel-shaped structure that extends 100 arcsec beyond the northern limb of the nebula. Our 3D reconstructions confirm and geometrically resolve a cavity at the jet's base that was suggested by earlier kinematic studies, establishing a direct physical connection between the filamentary network and the jet funnel. The morphology and kinematics indicate that the early pulsar wind nebula (PWN) played a central role in forming the jet. Several formation scenarios, which are not necessarily mutually exclusive, remain viable, including a bipolar outflow shaped by a circumstellar disk, a breach or underdensity in the ejecta shell, and a pre-existing progenitor mass-loss trail acting as a low-density channel. Collectively, these scenarios exhibit differing abilities to account for the jet's pronounced collimation, the absence of a southern counterpart, and its near-ballistic motion. Discriminating among them will require fully three-dimensional hydrodynamic simulations that trace the remnant's evolution from the progenitor phase through late-time PWN expansion.

23 pages, 15 figures, now published in ApJ. Animations available at https://doi.org/10.5281/zenodo.20822317 and https://www.youtube.com/watch?v=Pi7XSaW6ZPo