2019 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 | galaxy formation / turbulence / black holes / jets / magnetohydrodynamics |
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| Outline of Annual Research Achievements |
We made substantial progress in developing an FFT based Poisson solver that handles all types of boundary conditions. This is valuable for: 1) the determination of the "virial parameter" for star-formation and solving problems including self-gravity; 2) The construction of a Helmholtz decomposition function to decompose the velocity field in simulations into compressive and solenoidal modes. Both milestones will have strong implications for the science questions in the project proposal.
We made some progress in the preparation and execution of new simulations. We performed high-resolution wind-cloud interaction simulations, following the fragmentation, compression and destruction of a turbulent cloud embedded in a supersonic flow (Banda-Barragan et al 2019). A set of new test simulations of turbulent gas distributions at varying spatial resolutions have also been conducted. The convergence study has also led to hydrodynamic code improvements.
We conducted the following observations and analysis of galaxies experiencing AGN jet feedback: 1) A comparison with simulations of the radio source hosted by the galaxy UGC 05771, to investigate jet-ISM interactions in a galaxy with a young radio source (Zovaro et al 2019a). 2) A study of radio source B2 0258+35, suggesting that the turbulence in the cold gas in the centre of its host NGC 1167 is induced by the jets (Murthy et al 2019). 3) An investigation of the jet in 4C 31.04, in which a jet is dispersing the gas in the inner few 100 pc while the energy bubble is shocking molecular gas on kpc scales (Zovaro et al 2019b).
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
A delay in pursuing some of the subparts of the project has come about due to the unavailability of a new Master student in the past year.
The COVID-19 pandemic and state of emergency has resulted in a month of working from home, which has complicated collaboration with the Master student working on the analysis toolkit. Some problems accessing data on servers and setting up a new work code development environment on different machines has taken up time. Working locked away at home has been tough for the Master student, but our regular telecons meetings have ensured slow but steady continuation of the project.
Work with core collaborators Mukherjee and Bicknell has been delayed due to Mukherjee's change of position from Torino, Italy to Pune, India, where he now holds a faculty position with substantial teaching duties, and due to the passing of Bicknell's spouse in late 2019. This has mainly impacted the design and preparation of new magnetohydrodynamic simulations. As the year progresses, we expect to be back on track with the preparations of new simulations. The priority of new simulations for this project has also been temporarily lowered in favor of simulations for new development (under embargo) in a related but separate project, which PI Wagner is part of. While this will continue for another two months, some coding work will naturally resume in parallel.
Finally, parenting of a one year old and three year old reduced PI Wagner's effective working hours by 20% throughout the year, causing a slight overall delay in various aspects of the project.
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| Strategy for Future Research Activity |
The planning of this project has taken into account possible delays, in particular any related to the the unavailability of a Master student. We have accordingly decided not to pursue simulations of radiative AGN feedback. This will not affect the outcome of the project much, since the radiative mode is likely not to be a strong driver of turbulence.
We shall instead concentrate on the magnetohydrodynamic (MHD) setup of our simulations ensuring the completion of MHD simulations of AGN feedback by year 2. This is crucial, since MHD turbulence is fundamentally different to hydrodynamic turbulence. Instead of a self-consistent initialization of magnetic fields, we opt for "settling" simulation that dynamically evolves a uniform field in a turbulent medium, whose final snapshot can then be used as initial conditions for the full AGN feedback simulation.
Although successful observations have been conducted and associated papers written during the first year of the project, the closure of observational facilities around the world due to the COVID-19 pandemic will cause a delay in further observational work this year. Some of the work planned here for 2020 will be moved to 2021.
Other than the changes mentioned above, the remaining parts of the original plan for the project as outlined in the proposal and summarized in the Gantt chart will be pursued without change. PI Wagner shall still seek to enlist a Master student in 2021 for the final part of the project, who will likely apply the analysis toolkit to the full suite of MHD simulations to be conducted in year 2.
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| Causes of Carryover |
The budget for the first fiscal year was almost fully used up. The remaining budget was to be used for a domestic conference attendance at Kagoshima University in March, but this was cancelled due to the COVID-19 pandemic. While it is unclear how many conferences will go ahead in the next fiscal year, the rollover budget shall likely be used again for a domestic conference attendance.
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