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To do

Here are things I will be working on over the next few weeks:

  1. I am currently running two simulations to see how pulsed jets evolve, one with Beta = 1 and another with Beta = 5.
  1. Search the literature to find the conditions required for pulses to form shocks. From there, I will run a simulation to test it.
  1. Learn how radial equilibrium is disrupted after passing through a shock for a cylindrically stratified jet. I've already worked out some aspects of this but theres more to be done here.
  1. Contact Jonathan to ask about warm starts, axisymmetric simulations, and auxiliary variables in astrobear.

CE

Computer time

  • Code is now running on Cori, in addition to Anvil
  • Enough time for 1 run on Anvil (need to finish quota by June 30), and maybe another run on Cori
  • Plan to apply for more time on Cori

Reduction of ambient pressure and density

Method 1 from last post: Starting from t=0 with low ambient pressure and density

  • Abandoned this method
    • Eventually get Hypre error for tabular EOS run
    • Need to set MinDensity = ambient density, which is very inefficient
    • Get artifacts in ambient medium that slow code and force extra unwanted refinement

Method 3 from last post: Restarting from frame 86 of old runs and modifying ambient

  • Got this to work well with ideal gas EOS run
    • Reduced ambient density and pressure gradually over ~1-2 frames (0.25-0.50 days)
    • When done gradually, can retain momentum-conserving self-gravity
    • Works well when done using either conservative (modify density, momentum, energy) or primitive (modify density and pressure) forms
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run051_fr86_rho.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run051_fr87_rho.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run051_fr88_rho.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run051_fr89_rho.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run051_fr86_P.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run051_fr87_P.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run051_fr88_P.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run051_fr89_P.png
  • Does not quite work yet for tabular EOS run
    • If modify density, momentum and energy, then at some point pressure and temperature decrease to very low values, leading to artifacts and unwanted extra refinement
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run049_277_fr096_P.png
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run049_277_fr096_P_zoom.png
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run049_277_fr096_P_edgeon.png
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run049_fr096_P_T.png
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run049_fr096_100_T.png
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run049_fr096_104_T.png
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run049_fr104_T_rho.png
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run049_fr104_grid_lv1.png
    • If modify density and pressure, then code eventually crashes due to protections detecting NANs (energy)
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run054_fr878_Eint.png
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run054_fr087_Eint.png
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run054_fr086_Eint.png
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run054_fr878_Eint_zoom.png
      • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run054_fr878_Eint_E_zoom.png
    • If modify density and momentum alone, code eventually crashes
    • If modify density alone, code slows down catastrophically

Discussion

  • Solutions for reducing ambient in tabular EOS run
  • Strategy for paper

CE

Computer time

  • We need to perform 2 simulations
  • We may only be able to complete ~1 simulation using Anvil
  • DOE allocation?

Reduction of ambient pressure and density

Method 1 from last post: Starting from t=0 with low ambient pressure and density

  • Continued Run 026 (ideal gas) and Run 027 (MESA EOS), from last blog post
  • Run 026 took about ~1.75 hours per frame up to 19 frames
  • Run 027 took about ~2.5 hours per frame up to 34 frames
    • crashed shortly after frame 34
      • might have been caused by extra refinement (up to level 3) outside of desired level 4 refinement sphere
        • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run027_fr34_grid.png
        • I tried defining a shape like the level 4 refinement sphere but with "DEREFINE_OUTSIDE"
        • I also tried setting Refinement%Tolerance=-1d0
        • Both of these changes had no effect
        • Finally, in physics.data, changed refineVariableFactor to 0d0,0d0,0d0,0d0,0d0,0d0,0d0,0d0,0d0,0d0,0d0 from 1d0,1d0,1d0,1d0,1d0,1d0,1d0,1d0,1d0,1d0,1d0, to force derefinement outside of refinement object 1, and evolved from frame 34 to 35.
          • Prevents from crashing and speeds up simulation from 2.5 hours to 1.5 hours per frame
            • Is this method fine? If so, should I
              • continue from frame 35?
              • restart from frame 19 (when unwanted refinement was either absent or marginally present)?
              • restart from beginning of simulation?
  • Checked separation curve up to 19 days and it seems okay:
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/p_mult_282_277_026_027.png
  • Visualization up to 19 days looks okay but artifacts present, especially in Run 027 — harmless?
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run026_fr19_rho.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run282_fr19_rho.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run026_fr19_P.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run282_fr19_P.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run027_fr19_rho.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run277_fr19_rho.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run027_fr19_P.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run277_fr19_P.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run027_fr19_T.png
    • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run277_fr19_T.png

Method 3 from last post: Restarting from frame 47 of old runs and modifying ambient

  • Found that setting iSelfGravity=2 (non-momentum-conserving self-gravity) was the key to getting rid of the artifacts
    • Also speeds up simulation such that it is about half as fast as the original simulation at frame 47 to 47.1
    • However, when I try changing back to iSelfGravity=1 (momentum-conserving self-gravity) artifacts at boundary of level 1 grid appear (though artifacts at boundary of level 0 grid that I was seeing before — when iSelfGravity was left unchanged from 1 during the ambient modification — do not appear)
      • Figures show density, pressure and temperature, comparing frame 47 (left panel; original Run282, iSelfGravity=1), 47.1 (middle panel; low ambient, iSelfGravity=2) and 47.2 (right panel; iSelfGravity=1):
        • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run282_028_030_rho.png
        • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run282_028_030_P.png
        • https://www.pas.rochester.edu/~lchamandy/ambient_tests/run282_028_030_T.png
      • Is there a way around this?
      • If not, then how bad would it be to use iSelfGravity=2 for the remainder of the simulation?

Discussion

  • Method 1 working well now? Artifacts present in ambient but seem harmless
  • Decision about refineVariableFactor

CE

Reduction of ambient pressure and density

  • Note that pressure needs to be reduced to minimize ambient energy density
  • Density needs to be reduced to minimize ambient mass

Review of literature

  • In the table below, "UG" stands for uniform grid, and "MM" for moving mesh
  • Note: In Ohlmann+16a relaxation runs, the ambient density and pressure are much higher: 2e-10 g/cc and set to "roughly match the surface pressure of the star". He also says that the pressure gradient at the surface is not fully resolved, so the star expands a bit (leading to artificial motions in the ambient medium that do not affect the star) and then stabilizes during the relaxation run.
Paper Type Code Refine criteria Relaxation run rho_amb (g/cc) P_amb (dyn/cm2)
Chamandy+2018, 2019 AMR AstroBEAR Pressure gradient, density (effectively) no relaxation run, except for ModelB of paper I: velocity damping ramped down during 17.5 d ~ 5 freefall times 6.67e-9 or 1e-9 1e5 dyn/cm2, comparable to outer layer of star
Ricker+Taam 2008, 2012 AMR Flash 2nd deriv of rho (RT08), 2nd deriv of P, T (RT12) 1 dynamical time (13 d) with velocity damping 1e-9 pressure of the outermost layer of the star
Passy+ 2012 SPH/ UG Enzo(UG) N/A Velocity damping followed by no damping over a few dynamical times 1e-4 times lowest density of star Not stated
Ohlmann+ 2016a MM AREPO density and size relative to softening length Velocity damping (5 sound-crossing times) followed by no damping (5 sound crossing times) 1e-16 g/cc ~1e-4 erg/cc (calculated based on my priv. comm. with S.O.)
Prust+Chang 2019 MM MANGA Damp spurious velocities and energies 1e-13 g/cc T_amb = 1e4 K

Possible strategies

  1. Simply reduce ambient pressure and density.
    • This would cause pressure scale height at primary surface to decrease and it would no longer be resolved with standard resolution.
      • Since the standard resolution in the bulk of the envelope was chosen to resolve the pressure scale height at the surface, might as well reduce it (from envelope maxlevel = 4 to, e.g., envelope maxlevel = 3)
        • This seems to be the strategy of other groups, who seem to have low resolution in the envelope (except near the cores). Our resolution is probably still high by comparison.
      • Since the scale height will not be resolved, this will lead to artifacts (pressure waves owing to numerical diffusion)
        • This will lead to high temperature regions or steep pressure gradients in the ambient medium, leading to spurious motions that slow down the code
          • This can be averted to some extent by setting MinDensity, which is the floor density in the simulation
  2. First perform a relaxation run, and then follow the method of #1 above (as done by Ohlmann)
    • This is done by some other groups.
    • This could help to eliminate spurious motions in the ambient medium that slow down the code
    • We have argued in Paper 1 that performing a relaxation run with velocity damping does not make a big difference to the evolution
    • It is computationally expensive
    • Grid effects become severe during the relaxation run since the primary is not moving with respect to the grid
      • For this reason our relaxation run was only half as long as that of Ohlmann+2016 (we did not include the phase without damping)
    • In Ohlmann+2016, the relaxation run is peformed with high ambient pressure (Ohlmann, private communication). This ambient pressure is then removed for the simulation. To implement this, we need a way to change the ambient pressure without changing the star.
  3. That last point leads nicely into this 3rd option. Use our current simulations which resolve the pressure gradients at the surface, but at the appropriate time, when the secondary has already spiralled in (some time after first periastron passage), use the ambient tracer to reduce the ambient pressure and temperature
    • This can be done suddenly or gradually
    • Implementing it in the code seems to be straightforward
    • Total energy of the simulation would not be conserved
    • There can still be artificial effects of the ambient before this time.
      • If box is enlarged considerably then initial ambient mass will be very large
        • This may be harmless but one would have to justify it.
  4. Give the primary a hydrostatic atmosphere, which transitions to a uniform ambient medium at some large radius
    • Explored in a previous blog post (Run 199) and again below
    • It fails catastrophically, for reasons that are still not clear

Performing the Runs

  • Runs performed on Anvil using 16 nodes (2048 cores)
  • No queue time!
  • Total allocation on Anvil is 3,312,000 SUs = core-hours
  • 16 nodes = 2048 cores
  • We have already used 7% of the allocation for testing.
  • Want to redo the ideal gas and tabular EOS runs (Runs 282 and 277 — it is not necessary to redo 283)
  • If each simulation is 500 frames (as before) and each frame takes an average of 2.5 hours on 16 nodes, we have enough left for 1.2 simulations. So we may need to ask for a supplement.

Strategy #1 from above

  • Frame rate kept same as Run 282 (2e4 s) (recall Run 282 lasted for 500 frames = 115 days)
  • Simulations were run up to frame 2
  • In table below, "eml" stands for envelope maxlevel for refinement of bulk of envelope (innermost 6Rsun is refined at maxlevel 5), "wt" stands for wall time, and "fr" stands for frame
  • MinDensity is the density protection setting in physics.data
  • The first run, Run002, is the same as Run282
  • Runs started from scratch (lRestart=F)
  • For each run, first image shows density rho, second shows pressure P in dyn/cm2, and P/rho. In Run027 (tabular EOS), the third image replaces P/rho by temperature T in K.
ID iEOS Lbox (cm) eml rho_amb (g/cc) P_amb (dyn/cm2) MinDensity (g/cc) wt fr0 to 1 (h:m) wt fr1 to 2 (h:m) artifacts images
002/282 0 8e13 4 1e-9 1e5 1e-10 1:20 1:55 ~none https://www.pas.rochester.edu/~lchamandy/ambient_tests/run002_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run002_P_T.png
003 0 8e13 4 1e-10 1e4 1e-11 5:00 6:40 minor https://www.pas.rochester.edu/~lchamandy/ambient_tests/run003_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run003_P_T.png
005 0 8e13 4 1e-10 1e4 1e-15 6 days (estimated) I killed it N/A
004 0 8e13 3 1e-10 1e4 1e-11 1:05 1:20 minor https://www.pas.rochester.edu/~lchamandy/ambient_tests/run004_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run004_P_T.png
007 0 8e13 3 1e-11 1e3 1e-11 1:30 1:30 moderate https://www.pas.rochester.edu/~lchamandy/ambient_tests/run007_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run007_P_T.png
011 0 8e13 3 1e-11 1e3 1e-12 4:30 4:45 high https://www.pas.rochester.edu/~lchamandy/ambient_tests/run011_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run011_P_T.png
009 0 8e13 3 1e-11 1e2 1e-11 1:30 1:30 moderate https://www.pas.rochester.edu/~lchamandy/ambient_tests/run009_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run009_P_T.png
010 0 8e13 3 1e-12 1e2 1e-13 1.1 days (estimated) I killed it N/A
012 0 8e13 3 1e-12 1e2 1e-12 4:50 4:50 moderate https://www.pas.rochester.edu/~lchamandy/ambient_tests/run012_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run012_P_T.png
018 0 8e13 3 1e-12 1e1 1e-12 4:50 4:50 moderate https://www.pas.rochester.edu/~lchamandy/ambient_tests/run018_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run018_P_T.png
019 0 8e13 3 1e-13 1e0 1e-13 1.1 days (estimated) I killed it https://www.pas.rochester.edu/~lchamandy/ambient_tests/run019_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run019_P_T.png
020 0 8e13 3 1e-11 1e1 1e-11 1:30 1:30 moderate https://www.pas.rochester.edu/~lchamandy/ambient_tests/run020_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run020_P_T.png
021 0 1.6e14 3 1e-11 1e1 1e-11 2:20 2:20 moderate https://www.pas.rochester.edu/~lchamandy/ambient_tests/run021_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run021_P_T.png
022 0 1.6e14 4 1e-11 1e1 1e-11 1:30 1:30 moderate https://www.pas.rochester.edu/~lchamandy/ambient_tests/run022_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run022_P_T.png
024 0 1.6e14 4 6.63e-12 1e1 6.63e-12 1:58 1:53 moderate https://www.pas.rochester.edu/~lchamandy/ambient_tests/run024_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run024_P_T.png
026 0 1.6e14 4 6.63e-12 1e-1 6.63e-12 1:48 1:45 moderate https://www.pas.rochester.edu/~lchamandy/ambient_tests/run026_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run026_P_T.png
027 6 1.6e14 4 6.63e-12 1e-1 6.63e-12 3:31 3:29 moderate https://www.pas.rochester.edu/~lchamandy/ambient_tests/run027_rho_zoom.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run027_P_T.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run027_P_Tactual.png
  • Run time is principally determined by MinDensity (compare 007 and 011)
  • Reducing the pressure does not greatly affect the run time (compare 012 and 018 or compare 007, 009 and 020)
  • Reducing the pressure does not drastically change the level of artifacts present (compare 007 and 009)
  • Increasing the box size while reducing the base resolution proportionately does not greatly affect the run time (compare 020 and 022)
  • Ideal gas runs are faster than tabular EOS runs by a factor of 2 (compare 026 and 027)

Strategy #4 from above

I again tried to perform a run with an exponential hydrostatic atmosphere transitioning to a uniform ambient at large radius. This run is very similar to Run 199 of previous posts. There are severe artifacts.

ID iEOS Lbox (cm) eml rho_amb (g/cc) P_amb (dyn/cm2) MinDensity (g/cc) wt fr0 to 1 (h:m) wt fr1 to 2 (h:m) artifacts images
006 0 8e13 4 exp to uniform exp to uniform 1e-16 1 month (estimated) catastrophic https://www.pas.rochester.edu/~lchamandy/ambient_tests/run006_rho.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run006_P_T.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run006_P_grid.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run006_P_T_fr0.png

Strategy #3 from above

ID iEOS Lbox (cm) eml rho_amb (g/cc) P_amb (dyn/cm2) MinDensity (g/cc) wt fr47 to 47.1 (h:m) wt fr47.1 to 47.2 (h:m) artifacts images
016 0 8e13 4 1e-11 1e-11 1e-12 1:52 2:26 severe at ghost zones only https://www.pas.rochester.edu/~lchamandy/ambient_tests/run016_rho_P_47o1_47o2_lineout.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run016_P_T.png https://www.pas.rochester.edu/~lchamandy/ambient_tests/run016_P_T_zoom.png
  • Shock-like structure moving in from boundary at supersonic velocity
  • Ambient not getting modified correctly in ghost zones?

Discussion

  • Strategy #1 seems promising, but how much do artifacts affect the inspiral?
  • Setting MinDensity equal to ambient density helps to speed up the simulation (apparently by avoiding very high temperatures)
  • Smaller ambient density slows the code (why?). Good compromise is 6.63e-12 g/cc, which is 0.001x the lowest density in the initial primary star
  • Wall time is very insensitive to changing the ambient pressure. But very low ambient pressure (1e-5 dyn/cm2) caused the code to crash. Good compromise is 1e-1 dyn/cm2.
  • Wall time is insensitive to box size Lbox, provided base resolution delta_0 scales with Lbox. However, code crashed for Lbox=3.2e14 cm (do not know why). Also, grid effects are slightly amplified for a larger box (with coarser base resolution). A good compromise is Lbox=1.6e14 cm, which is 2x the box size of Runs 282 and 277. This will allow us to simulate up to 500 frames (115 days) with very little envelope material leaving the grid.

Conclusions

  • For a reasonable wall time, sufficient ambient reduction and minimization of artifacts, parameter values of Run 026/027 seem optimal.
  • Now need to test whether these runs reproduce the higher resolution runs (Runs 282/277) sufficiently accurately over the first ~40 days when effects of the ambient on envelope gas are still negligible.

CE

Computing

Anvil

  • Baowei has gotten the code working on Anvil (Purdue University)
    • No queue (as of now)
    • Maximum 16 nodes/2048 cores, 96 hours
    • More than twice as efficient as Frontera with 64 nodes/3584 cores, in terms of node-hours per frame
    • Implies that the code does much better with more cores/node and less nodes, for the same number of cores.
    • Anvil has AMD nodes, so nice that our code runs with AMD nodes (before we always used Intel)
    • Allocation ends June 30, so need to ask for extension.

Computer time

  • Extension for Anvil
  • Renew XSEDE (now under a different scheme)?
  • Renew Frontera?

New Analysis

Energy terms (star gas only, excludes ambient), evolution with time

https://www.pas.rochester.edu/~lchamandy/EoS/Figures/Env_E_terms_277_282_spancols_individ_totals_upto115days.png

  • The black and grey lines show that the envelope gas is being energized by the ambient after 40-50 days — problematic
    • Is the ambient energizing bound or unbound gas? If unbound, not a big problem. If bound, then implies that our estimates for the unbound mass are higher than they should be.
      • Ans: mainly unbound gas, but some bound gas too. The proof is that total energy of particles+bound gas rises, even though it must be transferring energy to unbound gas so should be losing energy rather than gaining:

https://www.pas.rochester.edu/~lchamandy/EoS/Figures/Env_E_terms_bnd_277_282_spancols_individ_totals.png Energy terms, bound envelope gas
https://www.pas.rochester.edu/~lchamandy/EoS/Figures/EnvMass_282_283_277.png Unbound mass with factors of two in particle-gas PE
https://www.pas.rochester.edu/~lchamandy/EoS/Figures/EnvMass_282_283_277_half.png Unbound mass without factors of two in particle-gas PE

So what to do?

  1. Admit the limitation and write up the paper as "part I". Focus on the bound gas.
  2. Redo the simulations with smaller ambient density and pressure
    • Requires some experimentation to get it working
    • Assuming we can get it to work, requires a few months of running and analysis, but computer time is available and pipeline is ready

CE

Research Plans and Ideas

Papers based on existing simulations

Paper Idea Description Simulations Status Comments
Drag Force II Model drag force at late times Runs 183, 263, 277, 282 Sims completed Sim 263 is like published AGB Run 183 but with particles of equal mass, to simplify modeling (Escala+2004)
Time-dependent energy formalism Extend/generalize energy formalism using insight from simulations Run 183, perhaps others as well Stalled because initial evolution is hard to reconcile with the new formalism Should be possible to get around this or just exclude early times
CE planet II Extend C+21 model Runs 259 (AGB+10MJup planet), 268 (AGB+0.08Msun, ideal gas), 269 (AGB+0.08Msun, MESA EOS) Notes and presentations but no write-up yet Simulations were not really successful, but Run 259 is first of its kind so worth presenting for its intrigue

Ideas for new simulations

Simulation Type Description Development needed Comments
Neutron star jet New regimes/ Parameter space exploration companion is a NS launching a powerful jet Ideally would improve accretion/jet model (AstroBEAR already allows for this). High velocity jet makes run expensive. Ideally would do one run with existing RGB primary and one with a massive primary.
Envelope ejection? Improve numerics Extend a simulation all the way to envelope ejection Reduce ambient, expand box, increase resolution Need to try running with a lower ambient energy density and compare to existing runs to see what we can get away with, need to look at energy conservation more carefully. Requires lots of computer time which we do not currently have.
Vary initial separation Parameter space exploration/ New regimes Compare sims with different initial separations, try to obtain RLOF phase Unclear, perhaps not much Expensive because of longer periods. Preliminary sims were done long ago: suggests that higher a_i leads to higher eccentricity during plunge-in. Existing work: Reichardt, De Marco, Iaconi, Tout & Price 2019
BD/planet companions New regimes Improve efforts to simulate RGB/AGB with BD/planet companion Not much, perhaps Expensive because of long orbital time. Only (modern) existing work: Kramer, Schneider, Ohlmann+ 2020
Include MHD New physics Include MHD in our best fiducial RGB run and see what happens Setup should not be too complicated, but bugs are likely Makes sense considering that our group has expertise in MHD. Only existing work: Ohlmann+2016b, Ondratschek, Roepke, Schneider+ 2021(preprint)
Include radiative transfer New physics Include flux-limited diffusion (already implemented into AstroBEAR) Needs lots of testing and learning the theory, need to put in MESA opacity tables and figure out how to use them Only existing work is a conference proceedings: Ricker+2019, the effect for our fiducial model is likely to be rather negligible. Realistic convection likely requires radiative transfer?
High mass regime (NS-NS merger progenitors) New regimes CE involving 8Msun primary and NS secondary Will likely require higher resolution. Larger range of scales so probably more challenging. May be expensive. One existing self-consistent global sim: Moreno+2022(preprint)
CEE involving two giant stars New regimes Binary pair is evolving to RGB at almost same time so get a CE involving envelopes of both stars Should not require much Would be expensive. No existing simulation? But see: Schneider+2019
Triple systems New regimes Introduce a second companion (multiple orbital configurations are possible) Not much, probably Triples may be quite important (according to S. Toonen). Limited number of existing simulations: Glanz+Perets 2021

CE

New Analysis

2D plots showing Spatial and Temporal dependence

Helium
Hydrogen
Conclusions:

  • Helium seems more important than hydrogen.
  • Recombination at first but then stagnates. Heating from inspiral balances cooling by expansion?

Ionization and Recombination (Volume-integrated, showing evolution with time)

Results
Conclusions:

  • Helium recombination HeIII —> HeII and HeII —> HeI are the dominant transitions
  • However, after t = 25 days, there is no net release of recombination energy

Energy terms (Star gas only, excludes ambient), evolution with time

All energy terms, not accounting for fluxes out of box: https://www.pas.rochester.edu/~lchamandy/EoS/Figures/Env_E_terms_with_init_th_277_282_spancols_individ_totals.png
Zoom-in on change in the recombination energy: https://www.pas.rochester.edu/~lchamandy/EoS/Figures/Env_E_terms_with_init_th_277_282_spancols_individ_totals_zoom.png
Conclusions:
1st Figure:

  • In both tabular EOS and gamma=5/3 runs, particle energy decreases at a steady (and still substantial) rate after t ~= 57 days, implying that the inpsiral does NOT stall.
  • Differences between runs are very small (<10%) implying that ionization and recombination do not play a very important role up until this point in the evolution
  • The release of recombination energy between about t = 6 days and t = 25 days leads to a slightly higher thermal energy compared to gamma=5/3 run (the two energy changes roughly balance one another, which makes sense).
  • EOS case manages to reduce gas-particle PE terms (by puffing up envelope?) after t ~= 45 days. From t ~= 45 days to t ~= 80 days, we also see a reduction in the thermal energy in the tabular EOS run as compared to the gamma=5/3 run, which is consistent with a puffing up. But this effect has faded by the end of the simulation at t ~= 80 days. This coincides with a transition from a deeper inspiral (compared to gamma=5/3 run) to a shallower inspiral (see also separation results, below).

2nd Figure:

  • The peak amount of recombination energy released is about 10%, which happens at t ~= 24 days
  • Thereafter, the net recombination energy relased reduces and drops to only 1% by the end of the simulation at t ~= 80 days.
  • The evolution of the recombination energy agrees well with the expectation from the ionization/recombination analysis above (using tracers and the Saha equation) FOR THE FIRST 20 DAYS. After that the tracer/Saha analysis predicts that almost 0 recombination energy is released whereas the plot of recombination energy (i.e. internal minus thermal) says that the net release of recombination energy between t ~= 20 days and t ~= 80 days is negative.
  • It is important to understand the reasons for this discrepancy

Inter-particle Separation, evolution with time

Separation curve: https://www.pas.rochester.edu/~lchamandy/EoS/Figures/p_mult_282_283_277.png
Conclusions:

  • Mean separation continues to decrease at the ends of both simulations (though at an ever-decreasing rate of decrease)
  • There is very little difference between the runs. Suprisingly, the difference between the MESA EOS run (with radiation energy removed — blue curve) and the tabular EOS run with internal energy replaced by thermal energy (green curve) is larger than the difference between MESA EOS and gamma=5/3 (red) curves.
  • Comparing MESA EOS (blue) and gamma=5/3 (red) curves, the MESA EOS run shows slightly smaller separation between t ~= 25 days and t ~= 70 days and slighly larger separation thereafter

Envelope Unbinding (Volume-integrated), evolution with time (showing Star tracer mass only)

With factors of two in particle-gas potential energy terms: https://www.pas.rochester.edu/~lchamandy/EoS/Figures/EnvMass_282_283_277.png
Without factors of two in particle-gas potential energy terms: https://www.pas.rochester.edu/~lchamandy/EoS/Figures/EnvMass_282_283_277_half.png
Conclusions:

  • Using the "internal energy" criteria (which makes no sense) would imply that the unbound mass is much higher, as found by other authors (top curve in both plots, and other authors use the equivalent of the second plot)
  • Using another criteria for unbound which is more reasonable, the MESA EOS run does lead to a higher unbound mass, of order 10% larger, peaking somewhere between t ~= 25 and t~= 40 days.
  • By the end of the MESA EOS simuation at t ~= 80 days, the difference is basically 0
  • The MESA EOS simulation with internal energy replaced with thermal energy (green/yellow) is much more similar to the gamma=5/3 run, as would be expected. But this run generally falls between the other two. This suggests that the recombination energy is actually slighly less important than the difference between blue and red curves would suggest.
  • Note that after t ~= 50 days, significant mass from the original primary is leaving the box, about the same in both runs (about 5% by t=85 days).
  • Generally speaking, the unbound mass is growing steadily by the end of both simulations (irrespective of what criterion for unbound is used)

Energy conservation, evolution with time

Results: https://www.pas.rochester.edu/~lchamandy/EoS/Figures/Energy_percent_change_new_282_283_277.png
Conclusions:

  • Energy is conserved to within ~2%, where the denominator chosen for this calculation is indicated on the plot
  • If one ignores the energy loss from reducing the softening radius, it is more like ~4% for the gamma=5/3 run and <1% for the MESA EOS run
  • The energy conservation inside the sphere with radius Lbox/2 (centered on the origin) is probably better: the gravitational potential due to mass outside this sphere is NOT included in the code, so envelope mass leaving this sphere reduces the gravitational PE inside the sphere, leading to an energy increase. This is likely the cause of the increase seen at the end of the simulations.

Status of runs

  • Run 277: MESA EOS (analyzed up to frame 344 or 77 days, completed up to frame 377 or 87 days)
  • Run 282: Ideal gas gamma=5/3 EOS (analyzed up to frame 374 or 87 days, completed up to frame 407 or 94 days)
  • Run 283: MESA EOS with recombination energy removed from EOS tables (completed up to frame 218 or 50 days on Frontera)
  • Run 276: MESA EOS with maxlevel increased by 1 compared to Run 277 (for convergence study — completed up to frame 47 or 11 days on Frontera)
  • Run 28?: MESA EOS with maxlevel reduced by 1 compared to Run 277 (for convergence study — not yet started on Frontera)
  • Run 271: MESA EOS with 7 times higher ambient (to explore role of ambient) (completed up to frame 235 or 54 days and will not extend)
  • Run 143 (fiducial run of past papers): Ideal gas gamma=5/3 EOS with 7 times higher ambient (to explore role of ambient) (completed up to frame 173 or 40 days and will not extend)

Next steps

  • Energy terms — include flux in total energy of primary gas tracer
  • Anvil
  • Continue to extend Runs 277 and 282 — but for how long?
  • Extend Run 276 (high res run)
  • Make progress on paper write-up
  • Explore overlapping ionization species regions to get a sense of how important they might be (< 10% difference?)
  • Calculate total angular momentum and check angular momentum conservation
  • PostProcessing to check energy conservation within sphere of radius Lbox/2 — expect it to be better than that in full box

CEE

EOS paper

Skeleton of paper with draft intro and methods sections: http://www.pas.rochester.edu/~lchamandy/CE_papers/EOS/eos.pdf.

Relevant papers

3D simulations:

  • Reichardt, De Marco, Iaconi+ 2020
    • Conclude that final separation unaffected by EOS (ideal or MESA) BUT actually in one of their simulations there is quite a large difference, with the tabular EOS producing a larger final separation by 16%.
    • Find that recombination energy release greatly increases the unbound mass
    • Unbound mass curves almost independent of EOS up until first periastron passage, and diverge thereafter, with tabular EOS resulting in roughly 50% more unbound mass in both sets of simulations, using a definition of unbound that includes thermal energy but not recombination or radiation energy (Fig. 2)
    • Find that released helium recombination energy is thermalized (released at too high an optical depth to radiate away)
    • In contrast, find that about half of released hydrogen recombination energy would be radiated away
    • Provide references for early papers: Lucy 1967, Roxburgh 1967, Han, Podsiadlowski & Eggleton 1994 and Harpaz 1998
    • Provide good summary of the recent literature and controversy over whether released recombination energy would radiate away
    • Point out in Sec. 2.0 that the helium mass fraction can vary quite a bit from on star to another, and this could potentially affect the results a lot
    • Provide useful information about the MESA EOS in Sec. 2.1 (we could refer to this summary in our paper to avoid having to repeat it)
    • End of Sec. 4.1 talk about ionization fronts staying at roughly constant radius, as opposed to e.g. moving inwards "counter to some expectations".
    • Fig 4 and 5 showing spatial and time dependence are particularly useful (I have done a similar thing but I did not do a spherical average, ignored overlapping a regions, and also had an extra plot for the tracers. Also, so far I was not planning to include the unbound mass plot for the ideal gas EOS run.)
    • Fig 6 is also interesting, purpoting to show the release of recombination energy (which is negative for ionization). However, I think it is flawed because it implicitly assumes that the gas does not move radially
    • Sec. 5 tries to estimate how much of the released recombination energy might be lost by convection+radiation (since the simulation cannot include those effects)
  • Lau, Hirai, Gonzalez-Bolivar+ 2022
    • Simulate CEE involving a 12 Msun RSG primary (focus on case with q=0.25)
    • Compare 3 sims: (1) Full EOS; (2) ideal gas; (3) ideal gas + radiation energy and pressure (but no recombination at all)
    • Find that the Run (1) unbinds about 114% more mass than Run (3) and 233% more mass than Run (2) (assuming KE+PE+TE energy density definition for unbound)
    • Find that recombination energy of helium contributes importantly to envelope unbinding, whereas recombination energy of hydrogen is mostly released into gas that has already become unbound
    • Find that the "final" separation in Run (1) is 34% larger than that of Run (2) and the final separation of Run (3) is 14% larger than that in Run (2)
    • Simulations are not very well converged with resolution (Fig. 9)
    • Also not converged with respect to softening length at late times (Fig. B1)
    • Fig. 13: Present spherically averaged color plots of ionization state at a given radius and time —> focus on regions where two ionization states (e.g. HeII and HeIII) coexist, as these regions are where gas is "actively recombining". Density of unbound gas is overplotted.
    • These plots also show contours for the tau=1, 10, 100 surfaces (spherically averaged)
    • Includes much discussion about the possibility of losses of recombination energy due to convection and radiation (Secs. 4.1 and 4.4)
  • Sand, Ohlmann, Schneider+ 2020
    • Simulations use OPAL EOS and ideal gas EOS
    • Compare ideal gas and OPAL sims and find that ideal gas unbinds ~20% and OPAL ~90% by end of the simulations (about 22% vs 78%, respectively, at time corresponding to the end of the ideal gas simulation), according to the bulk KE + PE density criterion for unbound gas
    • Show that the evolution of the released recombination energy during the simulation resembles the unbound mass evolution
    • The difference in unbound mass becomes larger after about 400 days, whereas the first periastron passage is at about 600 days.
    • Get convection (at some level)
    • "recombination energy acts behind the spiral shocks where the gas cools, boosting the expansion"
    • Determine tau=1 surface in postprocessing and equate this with location of photosphere (not stated whether they use MESA opacity tables to do this)
    • Find that most of the hydrogen ionization happens below the photosphere, but this number goes from 99% at t=296 days to 94% at t=1000 days to 80% at the end of the simulation (t=2500 days)
    • Similar results for runs with 2x smaller or 1.5x larger companion mass
    • "We find that the spiral-in is deeper by 17%–23% when not including recombination energy compared to the final separations in the simulations that include recombination energy. This can be explained by the fact that without recombination energy release the expansion of the envelope is slower and the transfer of orbital energy terminates later when little mass is within the orbit of the cores."
    • "We cannot follow the evolution for longer with confidence with our current numerical methods, because the energy-error rate exceeds the recombination-energy-release rate in the system and we can no longer decide whether a further envelope unbinding is physical or caused by numerical errors"
  • Kramer, Schneider, Ohlmann+ 2020
    • Simulations use OPAL EOS and one comparison simulation with ideal gas EOS
    • Sec. 3.3: The run with 0.08 Msun companion and 1 Msun primary (tip of RGB) unbinds about 78% of the envelope (OPAL) compared to 7% (ideal gas)
    • "Companions of even lower masses can certainly not eject the envelope when only tapping the orbital energy reservoir" — seems overly restrictive since simulations could evolve for much longer
  • Moreno, Schneider, Roepke+ 2021(preprint)
    • Simulations use OPAL EOS
    • Emphasize the "internal energy" criterion which tells them the envelope is almost completely unbound at the end of the simulation
    • Claim that recombination energy is very important for unbinding the envelope but provide no evidence for this statement
  • Ivanova & Nandez 2016
    • Identify some differences between 1D and 3D simulations
    • Strive to understand the transition between early phase (3D models) and late phase (1D models)
    • "The steady recombination outflow may dispel most of the envelope in all slow spiral-in cases, making the existence of a long-term self-regulated phase debatable, at least for low-mass giant donors."
    • Find that in some cases their can be a "recombination runaway" where recombination leads to expansion leads to cooling leads to more recombination
    • In other cases get a "steady recombination outflow"
    • Then can get "shell-triggered ejection" which is partly powered by recombinaton energy (see also Clayton+2017)
  • Nandez & Ivanova 2016
    • "We can clarify that there is no recombination energy stored in the ejected material at the end of the simulations."
    • "The role of the recombination energy for the CEE with a low-mass RG donor is not that it is necessary for the overall energy budget, as none of the considered systems were expected to merge by the standard energy formalism, but because the recombination occurs exactly at the time when the shrunk binary is no longer capable of transferring its orbital energy to the expanded envelope."
    • Modify energy formalism to include recombination energy and energy taken away by the ejecta
  • Nandez, Ivanova & Lombardi 2015
    • "Taking [recombination energy] into account helps to avoid the formation of the circumbinary envelope found in previous studies"
    • Use misleading definition of unbound that includes all internal energy density — classify > 0 energy density as "ejecta"
    • Find that for the ideal gas + radiation EOS, 50% of the envelope becomes unbound but for the MESA EOS the entire envelope is ejected
    • "Indeed, ionized material forms the circumbinary envelope initially. Recombination then takes place there, while the circumbinary envelope continues to expand. This results in the ejection of the circumbinary envelope and effectively of all the CE material."
    • "If instead the recombination energy had been released too early, the simulations would have ended up with unexpelled circumbinary envelope as in previous studies"
  • Chapter 9 of Ohlmann 2016 (phd thesis)
    • Their setup very similar to the one we are using (2 Msun RGB with R = 48 Rsun + 1 Msun companion and initial separation similar to ours, but they have 95% corotation to begin with)
    • Contains a critique of Nandez+2015
    • Very little difference in the separation curves between ideal gas and OPAL EOS simulations
    • More mass is unbound (KE+PE density unbound criteria) in the simulation with the OPAL EOS (Fig. 9.3 — compare blue and yellow curves)
    • Includes spatial analysis of where recombination energy is released and whether it contributes to unbinding (Fig. 9.5)
    • As in our simulation their high ambient temperature causes material near the surface to be ionized from t=0
    • Shows spatial evolution of ionization states in Fig. 9.6
  • Prust & Chang 2019
    • Study a system almost identical to our own (looking at two cases: 95% corotation or no initial spin like us) — their initial separation is slightly greater than us (52 Rsun compared to 48 Rsun), and they mention that their star is slightly bigger compared to Ohlmann+16a (the latter is almost identical to ours)
    • For internal energy density criterion, they get some ~65% of the envelope mass ejected by the end of the simulations (240 days)
    • For the KE+PE density criterion, they find that the it is only about 8% ejected (but rising) by 240 days: Unlike Ohlmann+16a but like us, they find a decreasing trend (before a rising trend) — see their Fig. 6
    • They do not try an ideal gas (gamma=5/3) model
    • Their final separation (no initial corotation) is 3.2 Rsun at 240 days — apparently still decreasing slowly by the end of the simulation (see Fig. 7)

1D simulations

  • Ivanova, Justham & Podsiadlowski 2015
    • Importance of helium vis-a-vis hydrogen recombination energy
    • Detailed study of usefulness of recombination energy in unbinding envelope in their 1D simulations
    • Find that ~90% of helium recombination energy is used to unbind the envelope, while for hydrogen it is less clear

Analytical modeling

  • Ivanova+ 2013
    • Argue that much of the hydrogen recombination energy does not get released until after envelope ejection
    • Argue that the subsequent release of this energy can explain LRNe
    • Argue that the luminosity comes from the recombination front, i.e. photosphere ~= recombination front
    • For the latter they cite Popov (1991) (see text after eq 7 in Popov 1991, in that model R_i is the radius of the front, dimensionless radius of the front is x_i). See also Kasen+Woosley(2009).
    • The location of this recombination front is expected to be "almost constant," in contrast with the CE ejecta, which moves out at a speed which is of order the escape speed
    • This also implies importance of helium vis-a-vis hydrogen recombination energy in assisting envelope ejection (see Lau+22)

Papers focusing on whether recombination energy is lost owing to radiation or convection+radiation before it can contribute to unbinding

Other recent CE papers not directly relevant

Status of runs

Summary:

  • Run 277: MESA EOS (completed up to frame 322 or 75 days on Frontera)
  • Run 282: Ideal gas gamma=5/3 EOS (completed up to frame 343 or 79 days on Frontera)
  • Run 283: MESA EOS with recombination energy removed from EOS tables (completed up to frame 218 or 50 days on Frontera)
  • Run 276: MESA EOS with maxlevel increased by 1 compared to Run 277 (for convergence study — completed up to frame 47 or 11 days on Frontera)
  • Run 28?: MESA EOS with maxlevel reduced by 1 compared to Run 277 (for convergence study — not yet started on Frontera)
  • Run 271: MESA EOS with 7 times higher ambient (to explore role of ambient) (completed up to frame 235 or 54 days and will not extend)
  • Run 143 (fiducial run of past papers): Ideal gas gamma=5/3 EOS with 7 times higher ambient (to explore role of ambient) (completed up to frame 173 or 40 days and will not extend)

Next steps

  • Energy terms graph and compare the two methods of computing the released recombination energy and check that they agree at all times
  • Combine tracer figures and make colors non-overlapping
  • Normalized energy (red/blue) plot for Run 282
  • Continue to extend Runs 277, 282 and 283
  • Make progress on paper write-up
  • Explore overlapping ionization species regions to get a sense of how important they might be (< 10% difference?)
  • Calculate total angular momentum and check angular momentum conservation

CEE

Conferences

  • Will submit blurb for the upcoming LANL meeting (date still not finalized), as requested of all participants by the organizer, Chris Fryer.

Jet paper

  • Submitted to MNRAS and astro-ph by Amy

EOS paper

Meeting?

A meeting before the end of Feb seems like a good idea. Times?

Writing

Made progress on Intro and Methods sections

Status of runs

  • 277 and 282 are now running on Frontera
  • Run 283 was not running properly (slow and chombos huge) ⇒ resubmitted using old executable (Baowei) and old module settings

Summary:

  • Run 277: MESA EOS (completed up to frame 288 or 67 days on Frontera)
  • Run 282: Ideal gas gamma=5/3 EOS (completed up to frame 295 or 68 days on Frontera)
  • Run 283: MESA EOS with recombination energy removed from EOS tables (completed up to frame 218 or 50 days on Frontera)
  • Run 276: MESA EOS with maxlevel increased by 1 compared to Run 277 (for convergence study — completed up to frame 47 or 11 days on Frontera)
  • Run 28?: MESA EOS with maxlevel reduced by 1 compared to Run 277 (for convergence study — not yet started on Frontera)
  • Run 271: MESA EOS with 7 times higher ambient (to explore role of ambient) (completed up to frame 235 or 54 days and will not extend)
  • Run 143 (fiducial run of past papers): Ideal gas gamma=5/3 EOS with 7 times higher ambient (to explore role of ambient) (completed up to frame 173 or 40 days and will not extend)

New analysis

Energy terms

We can calculate the released recombination energy two ways:

  1. Using the Saha equation and tracers to see how the ionic state has changed, calculate the corresponding energy released, and integrate over all gas (see notes from last post),
  2. Assume an ideal gas (with mean particle mass mu and temperature T taken from the simulation) and integrate to get the total thermal energy and subtract this from the internal energy to get the recombination energy. The negative of the net change in the recombination energy is equal to the released recombination energy.

We want to show that these two methods give approximately the same number (at every time).

I was able to roughly show this for the 7x higher ambient density run 271. However, with the new run 277, the ambient is at a high temperature and contains a lot of recombination energy. Therefore, it becomes more important to exclude the ambient gas when calculating the recombination energy by method 2 above. This calculation is in progress.

There is one small caveat. The potential energy term involving self-gravity of the gas makes use of the potential Phi due to all the gas (excluding particles). We made changes to the code to recalculate Phi excluding the ambient in postprocessing. This is expected to reduce the magnitude of the gas self-gravity potential energy term by 1%. However, it reduces it by 30%, so there must be a bug.

Unbound mass

For the same reason, ideally we would recompute the unbound mass using the correct Phi that does not include the ambient, but this would make such a small difference it may not be worth it (could be mentioned in a footnote). Consider that the unbound mass is perhaps already underestimated because we are including self-gravity of unbound envelope gas, which is maybe too conservative (e.g. Prust+Chang 2019 exclude it).

Ionization and Recombination

Spatial dependence http://www.pas.rochester.edu/~lchamandy/CE_papers/EOS/eos_ion_277.pdf. To reduce the number of plots I am planning to plot all the tracers in one plot, but to avoid overlapping them by only showing the tracer with the highest density at that location. This should be sufficient to make the points we want to make. Overlapping leads to ambiguity because the order of overlapping affects the shades so one can no longer read off the density from the color bar, so best to avoid overlapping.

Next steps

  • Compare the two methods of computing the released recombination energy and check that they agree at all times
  • Combine tracer figures and make colors non-overlapping
  • Continue to extend Runs 277, 282 and 283
  • Make progress on paper write-up
  • Explore overlapping ionization species regions to get a sense of how important they might be (< 10% difference?)
  • Calculate total angular momentum and check angular momentum conservation

CEE

Computing

  • Frontera issues for running CE code resolved by Baowei
  • Stampede2 allocation is basically used up — now moving all runs to Frontera

Jet paper

  • Ready to submit I think

EOS paper

Status of runs

Note that the frame interval is about 0.2315 days

  • Run 277: MESA EOS (completed up to frame 264 or 61 days on Stampede2)
  • Run 282: Ideal gas gamma=5/3 EOS (completed up to frame 268 or 62 days on Stampede2)
  • Run 283: MESA EOS with recombination energy removed from EOS tables (completed up to frame 218 or 50 days on Frontera)
  • Run 276: MESA EOS with maxlevel increased by 1 compared to Run 277 (for convergence study — completed up to frame 47 or 11 days on Frontera)
  • Run 28?: MESA EOS with maxlevel reduced by 1 compared to Run 277 (for convergence study — not yet started on Frontera)
  • Run 271: MESA EOS with 7 times higher ambient (to explore role of ambient) (completed up to frame 235 or 54 days and will not extend)
  • Run 143 (fiducial run of past papers): Ideal gas gamma=5/3 EOS with 7 times higher ambient (to explore role of ambient) (completed up to frame 173 or 40 days and will not extend)

New analysis

Unbound mass

Unbound mass including envelope gas only (i.e. excluding ambient) for runs 277 (MESA EoS without radiation), 282 (gamma=5/3 ideal gas), 283 (MESA EoS without radiation or recombination energy)

  • These are basically the final graphs except that the runs are all still being extended in time

https://www.pas.rochester.edu/~lchamandy/EoS/Figures/EnvMass_282_283_277.png https://www.pas.rochester.edu/~lchamandy/EoS/Figures/EnvMass_282_283_277_half.png

Separation

Updated separation graph now including Run 283 https://www.pas.rochester.edu/~lchamandy/EoS/Figures/p_mult_282_283_277.png

Energy conservation

Updated energy conservation graph now including Run 283 https://www.pas.rochester.edu/~lchamandy/EoS/Figures/Energy_percent_change_new_282_283_277.png

Ionization and Recombination

Spatial dependence http://www.pas.rochester.edu/~lchamandy/CE_papers/EOS/eos_ion_277.pdf.

  • Now for Run 277 (instead of old Run 271 which had a 7 times higher ambient density, slightly lower resolution and poorer energy conservation)
  • Instead of worrying about transparency or truecolor plotting, I decided to make separate graphs for each ionic tracer
  • Note that both the tracers and the graphs showing the ionization state at time t plotting only the gas density of the ionization species which is highest at that location.
    • I checked and the regions of overlap are small (as expected given the exponential temperature dependence) but not completely negligible…it is just something that needs to be looked at a bit more carefully and mentioned in the text somewhere, but not a problem really. And I think unavoidable given the nature of tracers.

Analysis involving spatially integrated quantities http://www.pas.rochester.edu/~lchamandy/CE_papers/EOS/eos_ion_vol_integ_277.pdf.

  • This analysis, too, considers a given species only in the region where it dominates (but separately for H and He)
  • Results are consistent with those obtained for Run 271 but now I've done it for the full time resolution (1 data point per frame).

Next steps

  • Continue to extend Runs 277, 283 and 282 and also extend the existing analysis (but need to worry about energy conservation, mass leaving box, and available SUs)
  • Energy terms vs time and check whether energy supplied by recombination leads to corresponding increase in thermal energy, as already done in comparison between old EOS run 271 and old ideal gas run 143.
  • Explore overlapping ionization species regions to get a sense of how important they might be (< 10% difference?)
  • Make progress on paper write-up and organize a meeting for all involved
  • Calculate total angular momentum and check angular momentum conservation (a must I would say)

CEE

Computing

  • Extension on Frontera — no news, write an email to Chris Hempel?
  • Parallel HDF5 (currently only being used for post-processing)
    • Bug has been identified and debugging ongoing (Jonathan)

Jet paper

  • Waiting for the OK to submit
  • Do another run? Or two? If so, what?
    • WD (as Run J6) but with flat profile? 10 x higher Mdot? Accretion off for simplicity? — but WD is almost order of magnitude more expensive because of jet speed
    • MS star with flat profile? 10 x higher Mdot as with Run J5? Accretion off for simplicity?

EOS paper

New analysis

  • Did unbound mass calculation for production runs 277 (MESA EoS without radiation) and 282 (gamma 5/3 ideal gas)
    • Results are generally consistent with the previous results from Run 271 (higher ambient density, lower resolution MESA EOS) and Run 143 (old gamma 5/3 ideal gas run from our other papers)
    • However, the difference between MESA EOS and gamma 5/3 runs is a bit larger
    • Also, unbinding remains flatter and goes up more at the end — this must be due to the 7 times decrease in ambient density
    • Note that these are not the final graphs because they include ambient gas, but the overall conclusions are unlikely to change

https://www.pas.rochester.edu/~lchamandy/EoS/Figures/Mass_282_277.png https://www.pas.rochester.edu/~lchamandy/EoS/Figures/Mass_282_277_half.png

  • Did the energy conservation analysis for both runs — we are under ~2% percent change

https://www.pas.rochester.edu/~lchamandy/EoS/Figures/Energy_percent_change_new_282_277.png

  • This is what their separation curves look like

https://www.pas.rochester.edu/~lchamandy/EoS/Figures/p_mult_282_277.png

Status of runs

The plan is to compare 3 runs (277,282,283) which are identical except for the EOS:

  • Run 277: MESA EOS (completed up to frame 247 on Stampede2)
  • Run 282: Ideal gas gamma=5/3 EOS (completed up to frame 250 on Stampede2)
  • Run 283: MESA EOS with recombination energy removed from EOS tables (completed up to frame 109 on Frontera)
  • Run 276: MESA EOS with maxlevel increased by 1 compared to Run 277 (for convergence study — completed up to frame 47 on Frontera)
  • Run 28?: MESA EOS with maxlevel reduced by 1 compared to Run 277 (for convergence study — not yet started on Frontera)

Next steps

  • Mass unbinding analysis of Runs 277 and 282, as above but now with star material only (i.e. excluding the ambient)
  • Extend Runs 277 and 282 — but for how long?
    • Energy conservation
    • Available SUs
    • What more will we learn?
    • Outflow through boundaries
    • Do we trust it as much after reductions in softening radius?
  • Extend Run 283 (but needs Frontera extension)
  • Ionization/recombination analysis as done with Run 271, now for Run 277

Fermi Project Update January 2022

The journal article on overleaf is at: https://www.overleaf.com/3756433924fzhskcnhbkmz


What Else I Need to Do?

  • Results Section: fix labels on parameter sweep (Fig 2). Use the parameter names on the paper rather than in the code
  • Appendix B: currently has the relevant timescales and ratios written down, what I need to do is figure out which 4/5 parameters or ratios uniquely determine the output. Or influence the output the most.
  • Appendix C: currently has density calculations (as function of radius). I need to copy my results showing technology as function of density. Then I need to use both of those to figure out technology as a function of radius.

What Is Left?

  • send out the paper to collaborators for review
  • write introduction, conclusion, and abstract

CE EOS Simulations

Computing

  • Allocation on Frontera ends on Dec. 31 — update?
  • Parallel HDF5 (currently only being used for post-processing)
    • Bug has been identified and debugging ongoing (Jonathan)

Energy conservation

  • Tested new poisson.f90 designed to explicitly conserve energy (though not yet including particles), as in Jiang+13.
    • Used low resolution CE run with periodic boundary conditions (so that flux of energy through boundaries does not change total energy in domain)
    • Found that energy conservation is worse than with the original poisson.f90, not better.
      • This means that there is a bug in the new poisson.f90 (could it be something obvious?)

EOS Runs

  • Computed volume integrated mass and released energy for Run 271, using Python, plotted, and made pdf file. Includes only 3 frames (frame 0, 100 and 200).

Runs for the paper

The plan is to compare 3 runs which are identical except for the EOS:

  • Run 277: MESA EOS (completed up to frame 170 and will go as far as energy conservation allows, maybe frame 300
  • Run 282: Ideal gas gamma=5/3 EOS (completed up to frame 33 and will go up to frame ~300).
  • Run 283: MESA EOS with recombination energy removed from EOS tables (not yet started, will go up to frame ~300)

We are also doing a high resolution run for a convergence study:

  • Run 276: MESA EOS with maxlevel increased by 1 (completed up to frame 47 and will go up to at least frame 65)

Next steps

  • Complete all runs and do basic analysis (separation vs time, energy conservation)
  • Redo unbound mass vs time plots to include only envelope gas (exclude ambient) — can wait for runs 277 and 282

CE EOS

Computing

  • Allocation on Frontera ends on Dec. 31
  • Parallel HDF5 (currently only being used for post-processing)
    • Bug has been identified and debugging ongoing (Jonathan)

EOS Runs

  • Continued analysis of Run 271:
    • New PLOT of energy terms that includes recombination energy
    • Volume integrated mass and energy released for the products of the various ionic transitions, for 3 snapshots (t=0, 23 d and 46 d)
    • Same, but divided into gas that is unbound and gas that is bound (at time t)
    • This analysis so far only on IDL (plot to screen)

Next steps

  • Do the above analysis (volume integrated mass and released energy for each species) but now for all simulation frames of Run 271, using Python
  • Continue with production runs (Stampede2 and Frontera)
  • Compute ambient unbound mass and subtract from total (as Amy has now done for jet runs)

CE (EOS)

Computing

  • Allocation on Frontera ends on Dec. 31
  • Parallel HDF5 (currently only being used for post-processing)
    • Bug has been identified and debugging ongoing (Jonathan)

EOS Runs

  • Slices comparing density of tracers for original ionization state with density of gas with a given ionization state at time t
  • Trying to improve energy conservation — Goal is to get simulation up to >100 days (c.f.~Ohlmann+16: 125 days; Prust+Chang19: 240 days)
    • Do this by testing adding refinement in different ways:
      • One extra AMR level
      • Larger region for AMR level 4
      • Larger region for max AMR level
    • Do we work to implement the new algorithm that includes gas potential energy in the explicit energy conservation (though not particle-gas potential energy) or do we carry on with what we have?
  • Energy conservation normalized to initial energy of star, not including recombination energy: Figure
    • So continuing to 100-150 days and staying <10% should be possible, particularly if we reduce softening radius 2-3 times…
    • Currently running a test where the highest AMR level refinement region is enlarged…results very soon

Next steps

  • Production runs on Frontera?
  • Compute ambient unbound mass and subtract from total (as Amy has now done for jet runs)
  • Compute total recombination energy of each species (e.g. HII, HeIII) as a function of time
  • Compute total recombination energy of each species (e.g. HII, HeIII) as a function of time for bound and unbound mass separately
    • This will tell us whether recombination energy is being released into bound gas (where it can be "useful") vs. unbound gas (where it cannot), c.f. Fig. 1 of Paper II
  • Some version of Figs. 9 and 10 of Paper IV that includes recombination energy

Fermi Project Update December 2021

Goal: find technology as a function of galactic orbital radius

  1. Find density as a function of radius

  1. Get technology as a function of density
    2a. Recreate surface plot made with Jonathan (with )

  • f is the fraction of systems that are settleable
  • is the normalized density of settleable systems within probe range
  • is the settlement civilization lifetime
  • X is the local fraction of settled systems to total systems

2b. Rerun the same parameter sweep but make

2c. Do some lineouts to get technology and X as function of density

  1. Interpolate to get density as a function of radius. (not entirely sure how to do this one)

CEE

Computing

  • Allocation on Frontera ends on Dec. 31
  • Storage
    • We have already exceded our storage on Ranch but they have moved most of it to tape to free up space for us. So we have almost 200 TB available.
  • Parallel HDF5
    • Debugging with Jonathan and Baowei

EOS Runs

  • Analyzed unbound mass comparing EOS Run 271 to old fiducial Run 143.
  • Ongoing Runs (Trying to optmize parameter values for final production run)
    • Run 273: ambient density reduced from 6.7e-9 g/cm3 to 1e-9 g/cm3
    • Run 274: RGB core particle mass equals m(r_soft) of original profile (skipping iteration over particle mass)

Next steps

  • Analyze energy conservation for runs 273 and 274
  • Analyze peak density for runs 271, 273 and 274
  • Compute ambient unbound mass and subtract from total (as Amy has now done for jet runs)
  • Make 2D slices (to compare) of:
    1. Mass density of Ionization state tracer (tracing gas with a given ionization state at t=0)
    2. Mass density of Ionization state (actual ionization state at time t)
  • Compute total recombination energy of each species (e.g. HII, HeIII) as a function of time
  • Compute total recombination energy of each species (e.g. HII, HeIII) as a function of time for bound and unbound mass separately
    • This will tell us whether recombination energy is being released into bound gas (where it can be "useful") vs. unbound gas (where it cannot), c.f. Fig. 1 of Paper II
  • Some version of Figs. 9 and 10 of Paper IV that includes recombination energy

Fermi Project Update 11/12/21

COMMON ENVELOPE SIMULATIONS

Jet paper

  • https://www.overleaf.com/project/601963d151b22065e09417a9
  • Meeting?
  • Figures still need improvement (see my comments in the figure captions)
  • A bit more analysis
    • J8 (WD run)
    • J2 (half companion mass run)
    • normalized binding energy slices (blue-red) to get a sense of where extra unbinding is happening

EOS project

  • Run 271 has now reached Frame 83 (almost 20 days)

https://www.pas.rochester.edu/~lchamandy/EoS/Figures/p_mult_271_143.png
https://www.pas.rochester.edu/~lchamandy/EoS/Figures/Mass_143_271.png
https://www.pas.rochester.edu/~lchamandy/EoS/Figures/Energy_percent_change_new_271.png

APN8e Talk

  • Given the time constraint (12 minutes + 3 minutes for questions) I have decided to talk only about the jet paper

COMMON ENVELOPE SIMULATIONS

New EOS runs

  • Similar to fiducial RGB run from Papers 1-4.
    • Same r_soft=2.4 Rsun
    • Same ambient density and pressure
    • 1 extra level of AMR around particles to improve energy conservation
    • A bit more automation to refinement part of code
    • Uses more recent version of AstroBEAR
    • If energy is well conserved can evolve up until separation = 2 r_soft=4.8 Rsun (do not expect full unbinding by then)
  • This is less ambitious compared to first two attempts which used factor of 6.7 lower density ambient, 4x smaller softening length, and either 3 or 2 extra levels of AMR around particles compared to fiducial run from Papers 1-4 (but these runs kept hanging, apparently due to insufficient memory).
Description Run ID Paper Primary Secondary Status Last complete frame Remaining cost Hanging? Resolution Ambient density Comments
MESA EOS 271 EOS RGB 1 Msun In progress 23 ~25% of remaining SUs? Not so far 4 AMR (envelope), 5 AMR (near particles) 6.7e-9 g/cc As fiducial RGB Run 143 but with extra AMR level, tracers for core/envelope/ambient and for initial ionization, and some minor code improvements including a bit more automation
MESA EOS without recombination energy ? EOS RGB 1 Msun Not yet submitted -1 ~25% of remaining SUs? N/A 4 AMR (envelope), 5 AMR (near particles) 6.7e-9 g/cc Same as Run 271
MESA EOS without hydrogen recombination energy (but including helium recombination energy) ? EOS RGB 1 Msun Not yet submitted -1 ~25% of remaining SUs? N/A 4 AMR (envelope), 5 AMR (near particles) 6.7e-9 g/cc Same as Run 271
Ideal gas EOS (gamma=5/3) ? EOS RGB 1 Msun Not yet submitted -1 ~25% of remaining SUs? N/A 4 AMR (envelope), 5 AMR (near particles) 6.7e-9 g/cc Same as Run 271