## Scientific Purpose

In support of the new Sloan III survey, which will measure the baryon oscillation scale using the Luminous Red Galaxies (LRGs), we have run the largest N-body simulation to date using $4120^3$ = 69.9 billion particles, and covering a volume of $(6.592 h^{-1}\mathrm{Gpc})^3$. This is over 2000 times the volume of the Millennium Run, and corner-to-corner stretches all the way to the horizon of the visible universe. LRG galaxies are selected by finding the most massive gravitationally bound, cold dark matter halos, not subject to tidal disruption, a technique that correctly reproduces the 3D topology of the LRG galaxies in the Sloan Survey. We have measured the covariance function, power spectrum, and the 3D topology of the LRG galaxy distribution in our simulation and made 32 mock surveys along the past light cone to simulate the Sloan III survey. Our large N-body simulation is used to accurately measure the non-linear systematic effects such as gravitational evolution, redshift space distortion, past light cone space gradient, and galaxy biasing, and to calibrate the baryon oscillation scale and the genus topology. For example, we predict from our mock surveys that the baryon acoustic oscillation peak scale can be measured with the cosmic variance-dominated uncertainty of about 5% when the SDSS-III sample is divided into three equal volume shells, or about 2.6% when a thicker shell with $0.4\lt z\lt 0.6$ is used. We find that one needs to correct the scale for the systematic effects amounting up to 5.2% to use it to constrain the linear theories. And the uncertainty in the amplitude of the genus curve is expected to be about 1% at $15 h^{-1}\mathrm{Mpc}$ scale. We are making the simulation and mock surveys publicly available.

## Authors

- Juhan Kim at CAC of Korea Institute for Advanced Study (KIAS; email contact: kjhan _at_ kias.re.kr)
- Changbom Park at KIAS
- J.Richard Gott III at Princeton University
- John Dubinski at University of Toronto

## Cosmological model of the Horizon Run

Cosmological model | $\Omega_{m,0}$ | $\Omega_{b,0}$ | $\Omega_{\Lambda,0}$ | $n_\mathrm{s}$ | $H_0$ (km/s/Mpc) | $\sigma_8$ |
---|---|---|---|---|---|---|

$\Lambda$CDM WMAP5 | 0.26 | 0.044 | 0.74 | 0.96 | 72 | 1/1.26 |

Simulations Name | HR1 |
---|---|

Box Size ($h^{-1}\mathrm{Mpc}$) | 6592 |

Number of CDM particles | $4120^3$ |

Starting redshift | 23 |

Initial power spectrum generator | Eisenstein & Hu (1998) |

## Outputs from the simulation

- Snapshot data at z= 0, 0.1, 0.3, 0.5, 0.7 and 1.0
- Mock SDSS-III surveys: eight non-overlapping all-sky ($4\pi$) surveys out to z=0.6
- A list of subhalos from all-sky ($4\pi$) survey out to z=1.29 (partly overlapping with the above 8 surveys)
- Past lightcone slice: a wedge of $\Delta\phi = 45^\circ$ and $64h^{-1}\mathrm{Mpc}$ width reaching the horizon
- Past lightcone slice-II: a wedge of $\Delta\phi = 5^\circ$ and $\Delta\theta = 10^\circ$ reaching z=23

## Pictures & Movies

Some images from the simulations are available here.

## Data Archive(Downloadable)

Mock catalogues, halo, and lightcone data can be downloaded here.

## Tables(Downloadable)

Tables from the simulations.

## Paper & Press Releases

The Horizon Run in the press.