Negative pressure issues

[Matthew Leeds]

All,

I've been having issues with negative pressures causing sfrhist to fail for weeks. I saw Laura Anderson had similar issues but I don't know that they're the same. If I leave max_level at 9 it seems to run fine (at least for some snapshots) but at max_level 10 or 11 the assertion Pk >= 0 fails. I added in some debug statements in sfrhist.cc and found that the mass gass is 0 for some particle but haven't been able to figure out why. I even printed out every value for s.m(i) in sphgrid-fits.cc but none were 0. I also verified the mass values are positive from pynbody. Attached are the config files and the output. (Some configuration parameters had to be moved to the param file for sunrise to find them). Any help would be greatly appreciated.

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Matthew Leeds

University of Alabama Class of 2017

[Chris Hayward]

Dear Matthew,

These values are actually for the Sunrise grid cells, not the simulation particles. So, I think that this error indicates that you have a young star particle in a region in which Sunrise thinks there is no gas (which would explain why it disappears if you use a lower refinement level). Is it possible that you have one or more young star particles in a region of very low gas density? What type of simulation is this (i.e. idealized galaxy or zoom-in)?

If you're willing to share the snapshot file (you can email me directly), I could try to diagnose the problem.

Cheers,

Chris

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Chris Hayward

Moore Postdoctoral Scholar in Theoretical Astrophysics

California Institute of Technology
Office: Cahill 326

Phone: 626-395-6987

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http://www.cfa.harvard.edu/~chayward