Type Ia Supernova Models: Asymmetric Remnants and Supernova Remnant G1.9+0.3

Abstract

The youngest Galactic supernova remnant G1.9+0.3, probably the result of a Type Ia supernova, shows surprising anomalies in the distribution of its ejecta in space and velocity. In particular, high-velocity shocked iron is seen in several locations far from the remnant center, in some cases beyond prominent silicon and sulfur emission.These asymmetries strongly suggest a highly asymmetric explosion. We present highresolution hydrodynamic simulations in two and three dimensions of the evolution from ages of 100 seconds to hundreds of years of two asymmetric Type Ia models, expanding into a uniform medium. At the age of G1.9+0.3 (about 100 years), our 2D model shows almost no iron shocked to become visible in X-rays. Only in a much higher-density environment could significant iron be shocked, at which time the model's expansion speed is completely inconsistent with the observations of G1.9+0.3. Our 3D model, evolving the most asymmetric of a suite of Type Ia SN models from Seitenzahl et al. ( 2013), shows some features resembling G1.9+0.3. We characterize its evolution with images of composition in three classes: C and O, intermediate-mass elements (IMEs), and iron-group elements (IGEs). From ages of 13 to 1800 years, we follow the evolution of the highly asymmetric initial remnant as the explosion asymmetries decrease in relative strength

A Rapid Ionization Change in the Nebular-Phase Spectra of the Type Ia SN 2011fe

“…If [Ca II] is indeed a reliable probe of the ejecta geometry, it is interesting that the [Ca II] line profiles are so similar. However, interpreting symmetric [Ca II] emission as evidence for symmetric ejecta introduces new tensions with the complex elemental distributions seen in some SN Ia remnants (e.g., Stone et al 2021).…”