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Simulating the Cosmic History of Baryons Discoveries Using Advanced Computing Michael L. Norman, Physics Dept., UC San Diego. validation. San Diego Supercomputer Center, UCSD. Keck Observatory, HI. surveys. Baryogensis : GUT phase transition t~10(-12) s speculative.
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Simulating the Cosmic History of BaryonsDiscoveries Using Advanced ComputingMichael L. Norman, Physics Dept., UC San Diego validation San Diego Supercomputer Center, UCSD Keck Observatory, HI SciDAC 6-30-05 M. L. Norman
surveys Baryogensis: GUT phase transition t~10(-12) s speculative Nucleosynthesis: formation of light nuclei t~1-100 s precision era (BBNS) Recombination: matter & radiation decouple t~380,000 yr precision era (CMB) Cosmic History of Baryons gravitational instability phase transitions Structure Formation: 50 Myr < t < 14 Gyr synthesis era linear perturbation theory nonlinear simulations SciDAC 6-30-05 M. L. Norman
We are here SciDAC 6-30-05 M. L. Norman
Cosmological N-body Simulation A. Evrard and the Virgo Consortium SciDAC 6-30-05 M. L. Norman
Multiscale Challenge Multiscale Challenge SciDAC 6-30-05 M. L. Norman
Grand Challenges in Computational Hydrodynamic Cosmology • Formation and evolution of stellar systems on all scales and epochs • Chemical enrichment and reionization of intergalactic medium • Formation of massive black holes and nature of the quasar phenomenon • Cosmological constraints on nature of dark matter and dark energy SciDAC 6-30-05 M. L. Norman
Outline • Cosmology’s Standard Model • Universe in a Box • History of Baryons: Discoveries using Advanced Computing • Exciting Opportunities Ahead • Cosmological limits on dark matter mass • Measuring dark energy equation of state SciDAC 6-30-05 M. L. Norman
Cosmology’s Standard Model • Concordance model • H0=72+/-7 km/s/Mpc • expansion rate accelerating (q0<0) • flat universe (k=0) • dominated by dark matter and dark energy • baryons minor constituent Perlmutter (2003), Physics Today SciDAC 6-30-05 M. L. Norman
Evidence for an Accelerating Universe S. Perlmutter, Physics Today (2003) SciDAC 6-30-05 M. L. Norman
Cosmic Microwave BackgroundTemperature Fluctuations 380,000 yr ABB NASA WMAP DT/T ~ Dr/r ~ 10-4 SciDAC 6-30-05 M. L. Norman
CMB Angular Power Spectrum SciDAC 6-30-05 M. L. Norman
Mass-Energy Budget of the Universe (WMAP+SNe+XRC) WL SciDAC 6-30-05 M. L. Norman
The Universe is an IVP suitable for computation • Globally, the universe evolves according to the Friedmann equation cosmological constant Hubble parameter mass-energy density spacetime curvature scale factor a(t) SciDAC 6-30-05 M. L. Norman
The Universe is an IVP... • Locally*, its contents obey: • Newton’s laws of gravitational N-body dynamics for stars and cold dark matter • Euler or MHD equations for baryonic gas/plasma • Atomic and molecular processes important for radiative cooling of gas and condensation to form stars and galaxies • Radiative transfer equation for photons Numerical astrophysics on a cosmic scale (*scales << horizon scale ~ ct) SciDAC 6-30-05 M. L. Norman
baryonic universe radiative transfer radiation background self-shielding photo-ionization photo-heating photo-evaporation ionizing flux absorption infall galaxies IGM feedback (energy, metals) SF-recipe multi-species hydrodynamics N-body dynamics cosmic expansion self-gravity dark matter dynamics SciDAC 6-30-05 M. L. Norman
Cold Dark Matter • Dominant mass constituent: Wcdm~0.23 • Only interacts gravitationally with ordinary matter (baryons) • Candidates: WIMPs or axions • Collisionless dynamics governed by Vlasov-Poisson equation • Solved numerically using fast N-body methods SciDAC 6-30-05 M. L. Norman
Gridding the Universe • Triply-periodic boundary conditions • Transformation to comoving coordinates x=r/a(t) But what about initial conditions? a(t1) a(t2) a(t3) SciDAC 6-30-05 M. L. Norman
Matter Power Spectrum P(k) Concordance model http://www.hep.upenn.edu/~max SciDAC 6-30-05 M. L. Norman
Gravitational Instability: Origin of Cosmic Structure very small fluctuations r C A <r> x B gravity amplifies fluctuations C A r <r> x B SciDAC 6-30-05 M. L. Norman
Formation of the Cosmic Web: Sky Dome Rendering for DomeFest 2005 Michael Norman, Brian O’Shea, UCSD Donna Cox, Robert Patterson, Stuart Levy, UIUC Steve Cutchin, Amit Chourasia, SDSC
Technical Details • Simulation (Enzo) • Dark matter, gravity, multispecies gas dynamics, photo-ionization and, radiative cooling • 1 billion cells, 1 billion particles • 512 cpu, NCSA TeraGrid cluster • Data • 512x512x512 arrays of density • 2000 timesteps • 1 Terabyte of data • Volume rendering • SDSC IBM DataStar SciDAC 6-30-05 M. L. Norman
Structured Adaptive Mesh Refinement (Berger and Colella 1989) SciDAC 6-30-05 M. L. Norman
Cosmological Adaptive Mesh Refinement(Bryan & Norman 1997) • Spatial dynamic range unlimited in principle • Today: • L/D = 104 in statistical volumes • L/D =1010 single objects of interest • Petascale: • L/D =106 in statistical volumes SciDAC 6-30-05 M. L. Norman
http://cosmos.ucsd.edu/enzo SciDAC 6-30-05 M. L. Norman
Enzo Implementation Details • Multi-scale in space and time • Arbitrary # levels of refinement • Arbitrary # grids per level • Portable, MPI-parallel, C++/C/F77 hybrid • Nonlocal dynamic load balancing • Ported to IA64, SGI Altix, IBM SP, BG/L, your mother’s Linux cluster, ….. SciDAC 6-30-05 M. L. Norman
Galaxy Formation and Large Scale Structure • Technical details • 2563 base grid • >32,000 grid patches @ 8 levels of refinement • 110,000 cpu-hrs on 128 cpu Origin2000 • 0.5 TB of data • Run at NCSA in 1999 Science credit: M. Norman, G. Bryan, B. O’Shea Image credit: D. Cox et al.
Computational Discoveriesusing Advanced Computing First baryonic condensations SciDAC 6-30-05 M. L. Norman
“Bottom-Up” Galaxy Formation • large galaxies form from mergers of smaller galaxies • where does this begin? • What are the first objects to form? Lacey & Cole (1993) SciDAC 6-30-05 M. L. Norman
First objects: a well-posed problem • Initial conditions specified: Wi, P(k) • Macroscopic dynamics understood • Microphysics of primordial gas known • Have 3D solution-adaptive algorithms • Have adequate computer power February 2003 SciDAC 6-30-05 M. L. Norman
Formation of First StarsAdaptive Mesh Refinement SimulationAbel, Bryan & Norman (2001) 1 x 10 x 100 x 1000 x Cosmic scales 104 x 105 x 107 x 106 x Solar system scales SciDAC 6-30-05 M. L. Norman
Birth and Death of the First Star in the Universe Science credit: T. Abel, G. Bryan, M. Norman Movie credit: R. Kaehler & T. Abel SciDAC 6-30-05 M. L. Norman
Impact of the first stars • the first stars in the universe began forming around 50 million years after the big bang • they were exceptionally massive and bright, bringing an earlier end to the cosmic “dark ages” than previously thought • when they exploded as supernovae they seeded the universe with heavy elements essential for planets and life • they kick-started the cosmogonic sequence which eventually formed galaxies, clusters and superclusters SciDAC 6-30-05 M. L. Norman
Computational Discoveriesusing Advanced Computing structure of intergalactic medium SciDAC 6-30-05 M. L. Norman
The Intergalactic Medium Source: M. Murphy SciDAC 6-30-05 M. L. Norman
Structure of the IGM quasar N=10243 L=54 Mpc/h Simulated HI absorption spectrum Earth Baryon Overdensity, z=3 SciDAC 6-30-05 M. L. Norman
Matter Power Spectrum P(k) LCDM http://www.hep.upenn.edu/~max SciDAC 6-30-05 M. L. Norman
Computational Discoveriesusing Advanced Computing whereabouts of missing baryons SciDAC 6-30-05 M. L. Norman
Missing Baryons at z=0 • Galaxies in local universe account for only 10% of baryons we know exist due to three independent measurements, which all agree to 2s • Big bang nucleosynthesis • CMB anisotropies • IGM absorption at high redshift • Where are the baryons now? SciDAC 6-30-05 M. L. Norman
Whereabouts of the missing baryons: Warm-Hot intergalactic gas warm-hot gas “galaxies” Cen & Ostriker (1998) N=5123 SciDAC 6-30-05 M. L. Norman
Exciting Opportunities Ahead(require Terascale and beyond) • Predicting properties of first galaxies • Understanding quasar-galaxy connection • Self-consistent simulation of the reionization era • Cosmological limits on dark matter mass • Measuring the dark energy equation of state SciDAC 6-30-05 M. L. Norman
Effect of DM particle mass on first objects: critical threshold 25 keV 10 keV O’Shea & Norman (2005) SciDAC 6-30-05 M. L. Norman
Measuring Dark Energy EOS • Principal goal of NASA/DOE JDEM mission • Approach: precision measurements of expansion history of the universe using Type Ia SN standardizable candles • Complimentary approach: redshift distribution of galaxy clusters SciDAC 6-30-05 M. L. Norman
Evrard et al. Single, 10243 P3M L/D=104 Dark matter only Our plan Multiple, 5123 AMR Optimal tiling of lightcone L/D=105 Dark matter + gas 0 -1 -2 -3 -4 -5 Lightcone Simulation(A. Evrard et al. 2003) ct (Gyr) SciDAC 6-30-05 M. L. Norman
Cosmic Simulator • A software facility for physical cosmology • A new collaboration between LLNL and UCSD • Scientific data management focus • Simulations: LLNL Thunder, BG/L • Data management: SDSC SRB • Public archive @ UCSD • Science driver: • LSST (Large Synoptic Survey Telescope) SciDAC 6-30-05 M. L. Norman