Dense Molecular Clouds in the Crab Supernova Remnant
Bentley, Rory O.; Fabian, A. C.; Combes, F.; Ferland, G. J.; Baldwin, J.; Castro-Carrizo, A.; Wootten, Alwyn; Loh, E.; Salome, P.; Shingledecker, C. N.
United States, France, United Kingdom, Germany
Abstract
Molecular emission was imaged with ALMA from numerous components near and within bright H2-emitting knots and absorbing dust globules in the Crab Nebula. These observations provide a critical test of how energetic photons and particles produced in a young supernova remnant interact with gas, cleanly differentiating between competing models. The four fields targeted show contrasting properties but within them, seventeen distinct molecular clouds are identified with CO emission; a few also show emission from HCO+, SiO, and/or SO. These observations are compared with Cloudy models of these knots. It has been suggested that the Crab filaments present an exotic environment in which H2 emission comes from a mostly neutral zone probably heated by cosmic rays produced in the supernova surrounding a cool core of molecular gas. Our model is consistent with the observed CO J = 3 - 2 line strength. These molecular line emitting knots in the Crab Nebula present a novel phase of the ISM representative of many important astrophysical environments.