# Presentation: 222548

## The Cosmic Simulator

- Daniel Kasen (UCB & LBNL)
- Peter Nugent, Rollin Thomas,
- Julian Borrill & Christina Siegerist

## The History of the Universe

- SC 2003

- Daniel Kasen

**Notes:**
A brief description of the history of the universe and the changing scales in size/time and energy.

## Foundations for a Cosmic Simulator

**Foundations for a Cosmic Simulator**

- Currently: 24 projects - 20% of Seaborg

*Planck*

*Sloan*

*LISA*

*JWST*

- Early
- Universe

- Galaxies & Large Scale Structure

- Star Formation

- Supernovae

- Black Holes

*JDEM*

- Observations

- Simulations

- SC 2003

- Daniel Kasen

**Notes:**
Describe the above observational experiments: Planck (CMB), Sloan (LSS), JWST (Star formation and the early universe) JDEM (Measurements of Dark Energy through supernovae and weak lensing), LISA (measurements of gravitational waves). The NVO (National Virtual Observatory) will tie the observations together so that one can look at any single event/location in space and retrieve the observational information. 
The quantity and quality of the data being gathered from observations and generated in simulations is changing  the way we do astrophysics. Developments in computer science - in particular the advent of tera-scale computing and the Grid as a distributed computing and data-management environment - are enabling this change. It is equally important that we carry out and manage the simulations in a similar fashion as the observations so that one’s output becomes the input of the next simulation so that we derive a consistent picture of the universe. In addition, the results of the simulations must be directly comparable to the observations.

## The National Virtual Observatory (NVO)

- The NVO links together disparate observational programs by:
-     - connecting distributed data components
-     - linking them to Grid computing resources
-     - developing standards for data interchange and data 		provenance

- Computational Astrophysics must be linked in a similar fashion, and soon, or the data will overtake us....

- SC 2003

- Daniel Kasen

## Cosmic Simulator

- Simulations no longer exist in splendid isolation, but now overlap in the intermediate regimes between their core domains.

-  Component simulations can be linked together to provide
-    a coherent, end-to-end, history of  the Cosmos.
-   Simulation data will be made accessible for comparison with
-     observations and for providing the initial conditions for the
-     next simulation step.
-  Key issues include computational steering, grid and sub-grid
-    selection and  interpolation, and data interfaces.

- SC 2003

- Daniel Kasen

## The Early Universe

- Observations:
- Planck/CMB
- Simulations:
- Julian Borrill

- SC 2003

- Daniel Kasen

## Galaxy/Structure Formation

- Observations:
- Sloan Digital Sky
- Survey (SDSS)
- Simulations:
- Joel Primack

- SC 2003

- Daniel Kasen

## Supernova Explosions

- Observations:
- Joint Dark Energy
- Mission (JDEM)
- Simulations:
- Mezzacappa,
- P. Nugent, D. Kasen

- SC 2003

- Daniel Kasen

## Black Holes and Gravitational Radiation

- Observations:
- Laser Interferometer
- from Space (LISA)
- Simulations:
- Ed Siedel

- SC 2003

- Daniel Kasen

## The Orgin of SupernovaeConfronting Theory and Observations

- SC 2003

- Daniel Kasen

**Notes:**
A few examples of the power of the cosmic simulator through supernovae:
Standard SN Ia is a WD accreting to the Chandrasekhar mass, sub-Chandra’s (He ignition on the outside forcing a shock wave down to the center to ignite the Carbon)  were proposed to explain a lot of the diversity seen in these supernovae. After 3 years the hydrodynamical models were finally confronted with the observations via spectrum synthesis. The winner, Chandra-mass progenitors. 
By placing the output of one model in a  standardized form to become input for the next simulation, science will be able to advance at a greatly increased pace.

## SNe Ia and their Companions

-  courtesy: http://zenith.as.arizona.edu/~burrows/movies.html

-   Marietta *et al.* (2000)
- examined the effects of a
- supernova running into its companion star.
- The impact carves out a hole
- in the supernova...

- SC 2003

- Daniel Kasen

## Supernovae With a Hole?

-    Unfortunately observed supernovae are too far away to be
-          resolved, so we can’t directly look for such a hole.

- SC 2003

- Daniel Kasen

## Supernova Spectra with simulations, we can interpret the colors

- SC 2003

- Daniel Kasen

## 3-D Monte Carlo Radiation Transfer

- Memory/Computing:
- ~ 106 cells/103 wavelengths
-        ~20 GB
- ~10^11 photons:
-        ~20,000 hours
- Scales well, currently runs
- on ~2056 processors on
- the IBM SP Seaborg at NERSC

- SC 2003

- Daniel Kasen

## Looking down and around the hole

- Changes in the spectrum provide signatures of the hole

- SC 2003

- Daniel Kasen

**Notes:**
The rotation of the line of sight of the SN ejecta showing the effects of the hole on the flux spectrum. 

## Diversity and AsymmetryA unifying picture?

- SC 2003

- Daniel Kasen

## Conclusions

**Astronomy faces a data avalanche. Breakthroughs and advancements in telescope, detector, and computer technology allow astronomical surveys to produce terabytes of images and catalogs. These datasets will cover large fractions of the sky spanning the spectrum from gamma-rays through optical to radio, and will allow us to probe fundamental questions in physics and astronomy that were unimaginable just a few years ago. **
**However, the study and analysis of this data can only be accomplished with equal advancements in computational simulations and data reduction. The National Academy of Science Astronomy and Astrophysics Survey Committee in its Decadal survey recommends a multi-agency effort to establish the National Virtual Observatory (NVO). **
**Given the increasing involvement of the DOE in astrophysics and its long history of excellence in computational research the Cosmic Simulator is a natural goal. It also provides a direct link to the NVO. Together these will provide both the***** framework***** to link the archival data sets, ongoing space and ground surveys, and *****computational resources***** necessary to produce the best science possible as we attempt to understand the Universe from beginning to end.**

- SC 2003

- Daniel Kasen