Evidence for Type Ib/c Origin of the Supernova Remnant G292.0+1.8

Circumstellar material (CSM) produced by mass loss from massive stars (≳10 M_⊙) through strong stellar winds or binary stripping provides rich information for understanding progenitors of core-collapse supernova remnants. In this paper we present a grating spectroscopy of a Galactic SNR G292.0+1.8, which is claimed to be a Type Ib/c remnant in a binary system according to recent studies. If G292.0+1.8 had experienced a strong mass-loss via binary interactions before its explosion, an oxygen-rich material produced in the He-burning layer is expected to be observed in the central belt-like structure formed by shock-heated CSM. Using the Reflection Grating Spectrometer onboard XMM-Newton, we detect N vii Lyα line (0.50 keV) for the first time in G292.0+1.8 and find that the abundance ratio of nitrogen to oxygen is significantly lower (N/O = 0.5 ± 0.1) than the solar value. This low N/O suggests that the progenitor of G292.0+1.8 experienced strong mass-loss and ended up as a Wolf-Rayet star exposing the He-burning layer at the presupernova. Comparing our result and the evolution models of single stars and binaries, we conclude that the progenitor of G292.0+1.8 experienced strong enough mass-loss to occur a Type Ib/c supernova. Our finding is another crucial piece of evidence for a stripped-envelope supernova such as Type Ib/c as the origin of G292.0+1.8.