SLIDE 1 Open-Source Astrophysics with the Enzo Community Code
Brian W. O’Shea Michigan State University
SLIDE 2 What is Enzo?
- N-body + hydro (+MHD + RHD + ...) block-
structured AMR code originally written at NCSA (by Greg Bryan & Mike Norman)
- Publicly available: http://enzo-project.org
- One of the PRAC codes for Blue Waters (two
separate projects: O’Shea et al., Nagamine et al.)
SLIDE 3 What science does Enzo enable?
➡ cosmology (large scale structure, dark energy,
galaxy clusters)
➡ galaxy formation (both in cosmological context
and isolated)
➡ star formation (Pop III/high redshift, modern-day) ➡ accretion disks ➡ turbulence (HD, MHD, self-gravitating) ➡ instabilities in compressible fluids ➡ probably more
SLIDE 4
History
SLIDE 5
1996-2003: closed-source!
SLIDE 6
March 2004: Enzo 1.0
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November 2008: Enzo 1.5
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June 2010: Enzo 2.0
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June 2010: Enzo 2.0
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June 2010: Enzo 2.0
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June 2010: Enzo 2.0
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June 2010: Enzo 2.0 October 2011: Enzo 2.1
SLIDE 13 The Enzo community today
- 25 contributors (~12 active developers) at >10
institutions
- ~200 people on enzo-users mailing list (~50% active?)
- ~80 million SUs devoted to Enzo simulations in 2011
from NSF, NASA, DOE (with more in 2012)
- Financial support from NSF (AST, OCI, PHY), NASA,
and DOE
- Complementary community: yt (http://yt-
project.org): see tomorrow’s talk by Matt Turk!
SLIDE 14 Development model
- Entirely distributed development model: small
number of devs per institution!
- Code distribution using mercurial (BitBucket)
- Use code forks / pull requests to move features
from development branches into main branch of the code
- Almost all development discussion takes place
- n archived, public mailing list and on Google
DOcs (meeting notes emailed out)
SLIDE 15 Community support
- Most developers are astrophysicists “scratching
their own itch” (and funded to do science!)
- Development spurred by ~1.5 workshops/year
+ periodic task-oriented “code sprints”
- Active mailing lists for users and developers
- Development funded by many streams:
universities, federal agencies, postdoctoral fellowships
- Complementary yt development has helped to
spur usage of Enzo!
SLIDE 16 Impact
- Enthusiastic and heavily-involved user/developer
community
- Enzo is widely known in astrophysics - strongly
represented in code comparisons, conference talks/posters - and highly trusted
- Code is flexible and extensible: high science/
dollar!
- Has spurred development of open-source science
- Involvement in this community has strongly
affected young scientists’ career trajectories
SLIDE 17 Challenges
- No “Fearless Leader” of development
process: hard to make major code revisions (esp. user-facing)
- Part-time developers: distractions, hard to
do “boring but important” infrastructure projects
- Significant work required to build
consensus and keep community together!
SLIDE 18
Recent Enzo- enabled results
SLIDE 19 Radio emission from cosmic ray electrons in galaxy clusters
Skillman, Hallman, O’Shea, Burns, Smith & Turk 2011, Astrophysical Journal, 735, 96 Skillman, et al. 2012, ApJ, submitted
and
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SLIDE 23 Evolution of the intergalactic medium
Smith, Hallman, Shull & O’Shea 2011, Astrophysical Journal, 731, 6
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Phase Flux
SLIDE 26
Self-gravitating star forming clouds
Collins et al. 2012, ApJ, 750, 13
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Reionization of the Universe
So, Norman, Harkness, Reynolds 2012 (in prep.)
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SLIDE 34 Conclusions
- Conversion of a code from closed-source to
an open-source community code is not without technical and sociological challenges.
SLIDE 35 Conclusions
- For the Enzo collaboration, this transition
has been worth it:
- Enhanced transparency/reproducibility (more
trust in the code)
- Larger user base: more eyes on the code,
wider adoption
- More and better science per dollar!
SLIDE 36 Conclusions
- The benefits can be seen in the wide
variety of science produced by Enzo users!
➡ cosmology ➡ galaxy formation ➡ star formation ➡ accretion disks ➡ turbulence ➡ fluid instabilities ➡ and more!
SLIDE 37
Questions?
SLIDE 38 Acknowledgments
- Collaborators: Michael Norman (UCSD/SDSC),
Matthew Turk (Columbia), Jack Burns (CU/Boulder), Eric Hallman (CfA/Tech-X), Robert Harkness (SDSC), Dan Reynolds (SMU), Sam Skillman (CU/ Boulder), Britton Smith (MSU), Geoffrey So (UCSD), Rick Wagner (UCSD/SDSC), John Wise (GATech)
- The Enzo development consortium
- Funding through NSF (AST, OCI, PHY), NASA, DOE
- Computational time through NSF (Teragrid/XSEDE),
NASA, DOE
