Supernova remnants (SNRs), what is left over of supernova (SN) explosions, are diffuse extended sources with a rather complex morphology and a highly non-uniform distribution of ejecta. General consensus is that such morphology reflects, on one hand, the physical and chemical properties of the progenitor SN and, on the other hand, the early interaction of the SN blast wave with the inhomogeneous circumstellar medium (CSM) formed during the latest stages of the progenitor’s evolution. Thus investigating the intimate link that exists between the morphological properties of a SNR and the complex phases in the SN explosion may help: 1) to trace back the characteristics of the asymmetries that may have occurred during the SN explosion, providing a physical insight into the processes governing the SN engines; 2) to probe the structure and geometry of the CSM immediately surrounding the SN, thereby mapping the final stages of the stars evolution.

Nevertheless, despite the great interest and importance in studying the connection between SNe and SNRs, only few efforts have been done in this direction, mostly by using a 1D approach (e.g., Yamaguchi et al. 2014, ApJL, 785, L27; Patnaude et al. 2015, ApJ, 803, 101). In fact linking SNe to SNRs is a rather challenging task due to the very different time and space scales of SNe and SNRs and due to the difficulty in disentangling the effects of the SN explosion from those of the early interaction of the blast with the surrounding medium. Understanding the present day structure and chemical stratification of ejecta in SNRs requires to describe the effects of anisotropies (inherently 3D) developing in the immediate aftermath of the SN explosion and to study the evolution of chemically homogeneous ejecta layers since the progenitor SN event. This would enable one to map the layers at the explosion to the resulting abundance pattern observed when the remnant is fully developed. Unfortunately, the 1D models miss all the complex spatial structures (requiring 3D simulations) observed in SNRs which are so difficult to interpret.

To overcome some of the limitations of previous studies, recently our group has started a project (awarded by PRACE - award N. 2012060993 - and by CINECA/ISCRA - awards N. HP10BDG92Y,2014, HP10CWYDMI,2016) bridging the gap between SNe and SNRs. In this project we used, for the first time jointly, a 1D relativistic radiation hydrodynamic model describing the first few days of a core-collapse SN, and a 3D hydrodynamic model of the following SNR development. We performed simulations describing two well studied core-collapse SNRs, namely Cassiopeia A and SN 1987A. In the former case, we investigated how the 3D morphology of the remnant reflects the characteristics (energies and masses) of anisotropies formed in the immediate aftermath of the SN by reproducing the observed spatial distributions and masses of Fe and Si/S (Orlando et al. 2016, ApJ 822, id. 22). In the case of SN 1987A, by comparing the model results with the observations, we identified the imprint of the SN on the X-ray emission of its remnant deriving the structure of the outer ejecta layers, and constraining the 3D pre-supernova structure and geometry of the environment (the nebula) surrounding the SN (Orlando et al. 2015, ApJ 810, id. 168). These pioneering studies have demonstrated that the approach describing the evolution from the SN explosion to the SNR development is very effective in gaining a deep physical insight of the phenomena occurring in the immediate aftermath of the SN explosion. These studies however are limited by the use of a 1D model of SN to describe the first few days of evolution: all modern multidimensional core-collapse simulations have shown that the stellar envelope and mantle, i.e. the ejecta, are already mixed and clumpy at the time of shock breakout. Providing a compelling and non-ambiguous link between the exploding star and the remnant thus requires to use a 3D model of SN explosion in order to calculate a realistic and accurate initial condition for the 3D model of SNR.

In the framework of the present project we aim at describing, for the first time, the complete 3D evolution of ejecta from the on-set of a core-collapse SN to the development of its remnant with unprecedented spatial resolution and completeness and following the evolution of the post-explosion isotopic composition of ejecta. This study will allow us to answer reliably important questions, never addressed or solvable before: how does the final remnant morphology reflect the characteristics of the SN explosion and, in particular, the asymmetries developing in the immediate aftermath of the SN? how do fine ejecta structures form during the remnant evolution? how does the original onion-skin nucleosynthetic layering of stellar material map in the remnant morphology?

Because of its youth and proximity, SN 1987A is an attractive laboratory for studying the tran-sition from the phase of SN to that of SNR. SN 1987A was a core-collapse SN and its evolu-tion has been accurately monitored in different wavelength bands since the outburst (Februa-ry 23, 1987). This has provided a wealth of high-quality data with unprecedented complete-ness, making SN 1987A an ideal template to study the SN-SNR connection. In our study, we propose to describe the evolution of SN 1987A from the on-set of the SN to the interaction of the blast wave with the inhomogeneous CSM. We will cover the first 50 years of evolution to make also predictions on the future remnant structure and morphology particularly important in view of the next astrophysical observatories of worldwide relevance Hitomi2 and Athena. The structure of ejecta 2 days after the SN event will be derived from a 3D hydrodynamic model describing the core-collapse of SN 1987A. The model is adapted from the 2D model of Ono et al. (2013, ApJ 773, id.161) but now extended to 3D. The model include the effects of gravity, the explosive nucleosynthesis using a nuclear reaction network (including the 19 most important nuclei), and the energy depositions due to radioactive decays. The model will provide reasonably complete and realistic conditions of the ejecta structure after the shock breakout at the stellar surface for the subsequent SNR evolution. From then on we will follow the system evolution, by using our 3D model of SNR (see Orlando et al. 2015, 2016) exten-ded to include also the effect of the ambient magnetic field. The plasma and magnetic field evolution will be modelled numerically by solving the time-dependent MHD equations, in-cluding the effects of radiative cooling, the back-reaction of accelerated CRs on shock dyna-mics, the deviations from electron-proton temperature-equilibration, and the deviations from equilibrium of ionization of the most abundant ions, in a 3D cartesian coordinate system (see Orlando et al. 2015 and 2016, for the details of the implementation). The nebula around SN 1987A will be described using the best-fit parameters derived by Orlando et al. (2015) which also allow to reproduce the lightcurves, the spectra, and the morphology of the remnant in the X-ray band. We will perform multi-species simulations to follow the evolution of the isotopic composition of ejecta and the matter mixing (see Orlando et al. 2016). In this way, we will be able to link the chemical distribution of ejecta in the remnant to anisotropies developing in the early phases of SN evolution. This point is rather important in the light of several studies suggesting that, in the next 3-5 years, the emission from the ejecta will become the dominant source of X-rays in SN 1987A and it will be possible to study in detail their chemical compo-sition and spatial distribution (Orlando et al. 2015, Frank et al. 2016, ApJ 829, id. 40).

The proposed simulation will shed light on the details of the complex evolution of structured ejecta and will contribute to unveil the link between the morphological properties of SNRs and the physical properties of the progenitor SN engine.



3D Navigable graphics Graphics available with the paper "Matter Mixing in Aspherical Core-collapse Supernovae: Three-dimensional Simulations with Single Star and Binary Merger Progenitor Models for SN 1987A", Ono et al. (2020, ApJ 888, 111)

Elements in Core-collapse Supernovae by Masaomi Ono on Sketchfab

Progenitor-supernova-remnant connection in SN1987A by Salvatore Orlando on Sketchfab