2020 Fiscal Year Research-status Report
Interstellar Turbulence by Supermassive Black-Hole Jets, Winds, and Radiation
| Project/Area Number |
19K03862
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| Research Institution | University of Tsukuba |
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Principal Investigator |
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | turbulence / star formation / hydrodynamics / galaxy formation |
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| Outline of Annual Research Achievements |
This year has seen substantial progress in this project, especially in the following tasks outlined in the original project proposal: 1) development of a fast Poisson solver capable of solving for the potential for a self-gravitating galactic disc for any box size and any boundary conditions in 3D; 2) The extension of the Poisson solver to conduct Helmholtz decompositions of the velocity field in galactic discs; 3) a completely renewed analysis of the star-formation rate in high-resolution 3D simulations of AGN jets interacting with a gas-rich galactic disc, showing, surprisingly, that positive feedback, as found in earlier work including by other groups, was incorrect. Instead, star-formation is reduced due to the strong turbulence generated by the AGN jets. Interestingly, the star-formation efficiency (the amount of stars formed per unit mass of gas) is enhanced by the same mechanism. These results have never before been seen in simulation of AGN feedback. We have partially identified a physical cause for the "negative" feedback. 4) Further analysis through the Helmholtz decomposition technique have revealed that the gas dynamics responsible for the observed change in star-formation and star-formation efficiency is due to vortical motions generated by the jet plasma flows. We are preparing two papers in which these findings will be presented. Two further papers have been submitted on turbulence-regulated AGN feedback: one exploring cloud destruction, and one showing the phenomena in ALMA observations of a radio galaxy with a massive gas disc (J2345-0449).
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
This project relies on strong collaborations with international colleagues. While the collaborations have been ongoing, exchange of ideas and progress on individual tasks has been delayed due to the inability to visit collaborators institutes and work on problems together - a major strategy in the original proposal, for which substantial travel funds were allocated.
Another Covid-19 related reason for a slight delay was the increased burden of teaching online (including exams) and on-demand (preparing lecture videos) which reduced the time available for research by up to approximately 20%.
Occasionally, raising a 2 and 4 year old child have reduced my ability to continuously work on this project, resulting in an approximately 10% reduction in productivity.
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| Strategy for Future Research Activity |
The next big steps in this project to be pursued in the final year are: 1) Perform full 3D magnetohydrodynamic simulations of relativistic jets interacting with gas rich galactic discs. Magnetohydrodynamic turbulence is fundamentally different to hydrodynamic turbulence, and the full analysis of how the star-formation rate and star-formation efficiencies vary with jet interaction will be performed on the new simulations; 2) Complete the physical theory of how vortical motions generated by the jets affect the star-formation rate and efficiency; 3) Perform cloud-crushing simulations of layers of turbulent radiative clouds and assess their survival rate; 4) Complete a physical picture of the negative feedback seen in the radio spiral galaxy J2345-0449.
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| Causes of Carryover |
The Covid-19 pandemic has forced me to cancel planned collaboration visits to Australia and Paris. A laptop purchase was planned, but has been delayed to mid 2021 as the model sought has not yet been released by the maker (Apple). A new laptop will be purchased this year to replace an old one that is reaching the end of its life to continue day to day work on the project. The rest of the amount will be used to attend conferences and, if Covid-19 restrictions permit, travel to visit collaborators. If funds remain, data storage units will be purchased to store the large amounts of data generated by the new simulations and the analyses thereof.
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