1 / 22

Rotation of Cosmic Voids (Lee & Park 2006, ApJ in press, astro-ph/0606477)

Rotation of Cosmic Voids (Lee & Park 2006, ApJ in press, astro-ph/0606477). Jounghun Lee & Deaseong Park (Seoul National University). OUTLINE. Origin and properties of voids Questions about voids yet to be answered A new nonparametric model for voids key assumptions analytic predictions

abiola
Télécharger la présentation

Rotation of Cosmic Voids (Lee & Park 2006, ApJ in press, astro-ph/0606477)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Rotation of Cosmic Voids(Lee & Park 2006, ApJ in press, astro-ph/0606477) Jounghun Lee & Deaseong Park (Seoul National University)

  2. OUTLINE • Origin and properties of voids • Questions about voids yet to be answered • A new nonparametric model for voids • key assumptions • analytic predictions • numerical tests • Discussion & conclusion • Ongoing & future works

  3. Clusters d(x) x Voids Origin of Voids and Clusters • Local extrema of the primordial density field

  4. Properties of Voids • Occupying 40% of the cosmic volume (Hoyle & Vogeley 2004) • Extremely underdense: dV ~ -0.9 • Expanding faster • Containing bluer galaxies with higher SFR (Hoyle et al. 2005) (2dFGRS, Hoyle et al. 2005)

  5. Unresolved Issues • Why are voids non-spherical ? • Not intuitive due to the very fact that they have low-density and undergo faster expansion • Why are void galaxies bluer with high SFR? • Not explained by the density-morphology relation (Hoyle et al. 2005)

  6. Clues from Previous Works • Shandarin et al (2006, MNRAS, 367, 1629) • Identifying voids using the excursion set approach in high-resolution simulations • Quantified the nonsphericity of voids • Suggesting that voids undergo stronger tidal effect

  7. Linear Tidal Torque Theory • Alignments between the spin axes and the intermediate principal axes of the local tidal tensors • Aspherical shapes of protohalos • Misalignments between the tidal and the inertia tensors

  8. A New Theory • Clusters form in the regions where the degree of alignment between T and I is strongest. • Less vulnerable to the tidal effect • Low spin-generation efficiency • Voids form in the initial regions where the degree of misalignment between T and I is weakest • More vulnerable to the tidal effect • High spin-generation efficiency

  9. Spin Generation Efficiency

  10. Tidal Effect on Voids • Generating the rotation of matter that make up voids around the center of mass. • Inducing the strong alignments between the void spin axis and the intermediate principal axis of local tidal tensor

  11. Key Prediction I • Correlations between the spin axes of neighbor spins

  12. Key Prediction II • Anti-correlations between the spin axes of voids and the directions to the nearest voids

  13. Void Spin-Spin Correlations

  14. Void Spin-Direction Correlations

  15. Finding Voids from Simulations • The Millennium-Run Galaxy Catalog • 21603 particles • Linear size of 500 Mpc/h • LCDM Cosmogony • 8964936 galaxies at z=0 • The Void-Finder by Hoyle & Vogeley (2002, ApJ, 566, 641) • 24037 voids with Ng > 30

  16. Measuring Void Spin

  17. Void Density Distribution

  18. Void Spin Parameter Distribution

  19. Analytic vs. Numerical I

  20. Analytic vs. Numerical II

  21. Discussion • Strong tidal effect on voids • Deviate void shapes from spherical symmetry • The less massive, the higher degree of triaxiality • Transfer high angular momentum to void galaxies • Block gas cooling • Delay star formation • Explain the high SFR and bluer colors of void galaxies:

  22. Summary and Conclusion • Constructing a new theory for cosmic voids • Quantifying the tidal effect on the voids • Void spin-spin correlation • Void spin-direction anti-correlation • Providing a quantitative physical explanations to the observed properties of voids • Providing a new insight to the large-scale matter distribution in a cosmic web

More Related