2020 Fiscal Year Research-status Report
Studying Massive Star Evolution from Progenitor to Supernova Remnant using Long-term Hydrodynamical Simulations and Machine Learning
| Project/Area Number |
19K03913
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| Research Institution | Kyoto University |
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Principal Investigator |
李 兆衡 京都大学, 理学研究科, 講師 (50611844)
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| Project Period (FY) |
2019-04-01 – 2024-03-31
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| Keywords | Supernova remnants / Stellar evolution / Supernova explosions / X-ray emission |
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| Outline of Annual Research Achievements |
In this fiscal year, we have made a significant progress [1] towards our goal for this grant of understanding the inter-relations between various kinds of massive star progenitors and their resultant supernova remnants (SNRs) through an extensive grid of simulation models connecting a stellar evolution code (MESA), a supernova (SN) explosion and explosive nucleosynthesis code (SNeC) and a SNR evolution and emission calculation code (CR-hydro-NEI or ChN). As the first milestone of our project in collaboration with our US co-workers at CfA/Harvard, U. of Pittsburg, Purdue U. as well as Japanese researchers at RIKEN, we have numerically surveyed on the evolution of over 500 massive stars from 10 to 30 solar masses through their SN explosions all the way to their SNR phases at an age of 7,000 years. We evaluated key parameters such as mass loss rates using different stellar wind schemes with or without rotation of the stars, and calculated the time evolution of the SNR hydrodynamics and thermal X-ray emission using a fully time-dependent computation of the ionization states and temperatures. The results were compared with currently available observation data of known SNRs. This comparison showed that bulk properties such as the energy centroid of strong X-ray lines like Fe-K alpha and SNR radii can be used effectively to infer the circumstellar environment around the SNRs and hence the mass loss histories and general nature of the SN progenitors. Our results bear important implication on establishing a link between SNR observations and studies of massive star explosion.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The first milestone originally envisioned in our proposal has been reached successfully as described above. In accordance with our original plan, in additional to the immediate results obtained in this first publication, we have established a robust computational framework that can connect massive star evolution, supernova explosion physics and SNR evolution seamlessly in a self-consistent fashion. This "production line" will allow for efficient parameter studies by outputting batches of models to cover different types of objects. Moreover, the fact that the simulation code is inherently designed to be modular allows for implementation of additional physics and observables that have not been yet included in the first study (see below).
In addition to this main publication, in collaboration with colleagues at Kyoto U., ISAS/JAXA and NASA/GSFC, we have also obtained a significant observational result [2] on the Galactic SNR Tycho using the Chandra X-ray Observatory. We discovered that, to everyone's surprise, that Tycho's SNR is going through a rapid deceleration phase during this past few decades. Using a new careful proper motion measurement of the shock expansion, we discovered that the south and west parts of the remnant are decelerating especially quickly, implying that Tycho has most probably expanded into a wind-cavity surrounded by a molecular cloud. This has profound impact on the progenitor origin of Tycho as a Type Ia SNR, and our discovery has provided a strong evidence for a single-degenerate origin for Tycho. This work has been published in a refereed journal.
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| Strategy for Future Research Activity |
The main things that are still left to be done with the project include the following:
1) Increase the mass range of the massive star progenitors, and include those with non-trivial mass loss histories with significant envelope stripping due to effects such as binary interactions.
2) Include calculations of observables such as Doppler broadening and thermal broadening
of the line emissions with projection effects. Future X-ray observatories with micro-calorimeters onboard such as ATHENA and XRISM will be able to discern these differences in the X-ray emission properties.
3) We are planning to expand our targets to Type Ia objects as well using a similar methodology. This work is currently in progress in collaboration mainly with a graduate student and a colleague at U. of Pittsburg.
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