Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

3D insights into SN 1987A: ALMA observations compared to hydrodynamical explosion simulations

R. Wesson, M. Gabler, M. Lyons, J. Wildman, Mikako Matsuura, H. -T. Janka, B. Giudici, P. Cigan, H. L. Gomez, R. Indebetouw, A. M. S. Richards, A. Wongwathanarat

TL;DR

This study constructs 3D maps of CO and SiO in SN 1987A from two epochs of ALMA data and converts them into mass-velocity distributions under homologous expansion. By comparing these observations to a suite of Prometheus-HOTB hydrodynamical explosions across multiple progenitor types, the authors find that binary-merger blue supergiant models best reproduce the CO distributions, while SiO remains challenging to match, suggesting insufficient mixing of Si. A robust correlation emerges between the densest C+O ejecta and the neutron-star kick direction, enabling a tentative kick toward the observer at about $45^\circ$ north for SN 1987A. Collectively, the results support a neutrino-driven explosion in a binary-merger progenitor framework and demonstrate the power and limitations of 3D observational–theoretical comparisons for constraining SN progenitors and explosion physics.

Abstract

We obtain three-dimensional distributions of CO and SiO molecules from high spatial resolution (0.03--0.06") ALMA observations of SN 1987A at two different epochs. The evolution between these two epochs is consistent with homologous expansion. From these 3D maps, we reconstruct the 3D mass distributions of the ejecta in CO and SiO molecules, which we compare with those obtained by state-of-the-art, long-time hydrodynamical supernova explosion models computed with the Prometheus-HotB code for 10 different progenitors, including both red and blue supergiants. The models which best match the mass distributions correspond to explosions of binary-merger blue supergiant progenitors; at least two such models approximately reproduce the observed CO morphology. In contrast, the SiO velocity distribution and morphology are not as well reproduced in these models, indicating insufficient mixing of Si into the outer layers already at the progenitor stage. The theoretical models suggest a strong correlation between the centre of mass of the densest carbon- and oxygen-rich ejecta and the direction of the neutron-star kick. If such a correlation also applies to the CO emission in the ejecta of SN 1987A, the kick of the compact remnant is expected to point towards the observer, at an angle of approximately $45^\circ$ to the north.

3D insights into SN 1987A: ALMA observations compared to hydrodynamical explosion simulations

TL;DR

This study constructs 3D maps of CO and SiO in SN 1987A from two epochs of ALMA data and converts them into mass-velocity distributions under homologous expansion. By comparing these observations to a suite of Prometheus-HOTB hydrodynamical explosions across multiple progenitor types, the authors find that binary-merger blue supergiant models best reproduce the CO distributions, while SiO remains challenging to match, suggesting insufficient mixing of Si. A robust correlation emerges between the densest C+O ejecta and the neutron-star kick direction, enabling a tentative kick toward the observer at about north for SN 1987A. Collectively, the results support a neutrino-driven explosion in a binary-merger progenitor framework and demonstrate the power and limitations of 3D observational–theoretical comparisons for constraining SN progenitors and explosion physics.

Abstract

We obtain three-dimensional distributions of CO and SiO molecules from high spatial resolution (0.03--0.06") ALMA observations of SN 1987A at two different epochs. The evolution between these two epochs is consistent with homologous expansion. From these 3D maps, we reconstruct the 3D mass distributions of the ejecta in CO and SiO molecules, which we compare with those obtained by state-of-the-art, long-time hydrodynamical supernova explosion models computed with the Prometheus-HotB code for 10 different progenitors, including both red and blue supergiants. The models which best match the mass distributions correspond to explosions of binary-merger blue supergiant progenitors; at least two such models approximately reproduce the observed CO morphology. In contrast, the SiO velocity distribution and morphology are not as well reproduced in these models, indicating insufficient mixing of Si into the outer layers already at the progenitor stage. The theoretical models suggest a strong correlation between the centre of mass of the densest carbon- and oxygen-rich ejecta and the direction of the neutron-star kick. If such a correlation also applies to the CO emission in the ejecta of SN 1987A, the kick of the compact remnant is expected to point towards the observer, at an angle of approximately to the north.
Paper Structure (21 sections, 6 equations, 26 figures, 7 tables)

This paper contains 21 sections, 6 equations, 26 figures, 7 tables.

Table of Contents

  1. Introduction
  2. ALMA observations
  3. Spectral grids
  4. Integrated line profiles
  5. 3D plots
  6. Mass distributions
  7. Hydrodynamical models
  8. Comparison of observations with models
  9. Velocity vs mass distributions
  10. 3D maps of C+O and Si+O of theoretical models
  11. Comparison of SiO and CO morphologies
  12. Neutron star kick geometry in theoretical models
  13. Summary and discussion
  14. Conclusions
  15. Noise characteristics
  16. ...and 6 more sections

Figures (26)

  • Figure 1: The analysed region, superimposed on the CO $J$=2--1 first epoch image, collapsed along the velocity axis.
  • Figure 2: Spatially integrated emission line profiles for each of the six data cubes. Velocities are in the rest frame of the LMC (+287 km s$^{-1}$ relative to the Local Standard of Rest (LSR))
  • Figure 3: 3D intensity maps of CO ($J$=2--1) emission, epoch 1. In this and subsequent figures, the plane of the equatorial ring is indicated in blue, and different colour maps are used for material above and below that plane. An orange point indicates the position of the explosion, and a red arrow points from the SN towards the observer in each panel. The volume represented in each panel measures 40,000 AU on each side and is centred on the supernova explosion position.
  • Figure 4: 3D intensity maps of SiO ($J$=5--4) emission, epoch 1. All panels show the equatorial ring plane (blue), explosion site (orange point), and observer direction (red arrow). Colour coding distinguishes material above and below the plane. Box size: 40,000 AU.
  • Figure 5: 3D maps of SiO ($J$=5--4), epoch 2. All panels show the equatorial ring plane (blue), explosion site (orange point), and observer direction (red arrow). Colour coding distinguishes material above and below the plane. Box size: 40,000 AU. The lower sampling in velocity space compared to the epoch 1 data causes the apparent gaps in the -90$^\circ$ and +90$^\circ$ panels.
  • ...and 21 more figures