On the progenitor of the Crab Pulsar

Abstract

We investigate the progenitor of the Crab supernova by examining the remnant's surrounding stellar population. The Crab is interesting because of the apparently low energy and mass of the supernova remnant. We also know it was not a binary at death and that the explosion formed a neutron star. Using Gaia EDR3 parallaxes and photometry, we analyse stars inside a cylinder with a projected radius of 100 pc and spanning distances from $\sim 1600$ to 2300 pc set by the $2\sigma$ uncertainties in the Crab's parallax. We also individually model the most luminous stars local to the Crab. The two most luminous stars are blue, roughly main sequence stars with masses of $\sim 11\, {\rm M}_{\odot }$. We estimate the stellar population's age distribution using solar metallicity PARSEC isochrones. The estimated age distribution of the 205 $M_{\mathrm{ G}} < 0$ stars modestly favour lower mass stars, consistent with an AGB star or a lower mass binary merger as the progenitor, but statistically we cannot rule out higher masses. This may be driven by contamination due to the $\sim 700$ pc span of the cylinder in distance.