Thesis Title: Modeling X-ray Emission from Type Ia Supernova Remnants in Different Circumstellar Environments

Abstract: The nature of Type Ia supernova (SN Ia) explosions remains an open issue, with several contending progenitor scenarios actively being considered. The parameter space for mass loss in these progenitors is large, with different scenarios favoring different mass loss regimes. We examine these scenarios using hydrodynamic and non-equilibrium ionization simulations of the interaction between the SN ejecta and the ambient medium into the supernova remnant (SNR) phase. We create large grids of models spanning different regions of parameter space considering circumstellar structures formed by mass loss from the progenitor system. We compare the bulk properties (ages, radii, and Fe Kα centroids and luminosities) of our simulated SNRs to the observed properties of known Type Ia SNRs in the Milky Way and the Magellanic Clouds.

We vary mass loss rate, wind velocity, and outflow duration, and evolve SNR models in this grid of uniform and isotropic circumstellar structures. We find that roughly 50% of these young Type Ia SNRs had progenitors that did not substantially modify their surroundings on ∼pc scales. The other half of our sample can be divided in two distinct classes. A small subset of SNRs (∼15%) have large radii and low Fe Kα centroids and are likely expanding into large cavities excavated by fast (∼1000 km/s), sustained progenitor outflows. The majority of the SNRs that are expanding into a modified medium (∼ 35%) show evidence for dense material, likely associated with slow (∼10 km/s) progenitor outflows.

We also create a grid of models involving a SN Ia explosion inside a planetary nebula (PN) in the aftermath of a stellar merger triggered by a common envelope (CE) episode. We conclude that models with a delay ≲ 1, 000 yr between CE and SN Ia are hard to reconcile with the observations. However, models with a longer delay between the CE episode and the SN explosion (∼ 10, 000 yr) are closer to the observations and may be able to explain the bulk properties of some Type Ia SNRs.