1. Analysis of Voids in the Large-Scale Structure of the Universe Mahdi Khadem

2. Cosmology Cosmology is the science of studying the Universe in its totality. Cosmology is the science of studying the Universe in its totality. It attempts to make sense of the large-scale nature of the material world around us, by the method of the natural sciences. It attempts to make sense of the large-scale nature of the material world around us, by the method of the natural sciences.

3. Structure Formation Cosmic Microwave Background radiation (CMB) gives us an exceedingly important probe of the history of structure formation in the evolving universe. Cosmic Microwave Background radiation (CMB) gives us an exceedingly important probe of the history of structure formation in the evolving universe.

4. Large-scale structure of the Universe There are various structures in the Universe: There are various structures in the Universe: Groups and Clusters Groups and Clusters Walls and filaments Walls and filaments Voids Voids SDSS data and the CfA2 catalog

5. Voids There is not a standard definition for “void” in cosmology. There is not a standard definition for “void” in cosmology. Weygaret and Kampen (1993): Weygaret and Kampen (1993): Irregular low-density regions in the density field El-Ad and Piran (1997) El-Ad and Piran (1997) Continues volumes that do not contain any wall galaxies. …

6. Void Finding Process We should have spatial coordinates for galaxies. We used the COSMOS data catalogue for 433065 galaxies: Spatial constraints:

7. Converting RA and Dec to galactic longitude (l ) and galactic latitude (b) [6]:6 Void Finding Process

8. Converting Zphoto to comoving distance: Hubble’s law: [3][3]

9. Void Finding Process Converting Zphoto to comoving distance: Einstein-de Sitter Universe: [5][5] [7][7] [7][7]

10. Void Finding Process

12. Making volume-limited samples: Void Finding Process

13. Void finder algorithms: Void Finder (Piran 1997, Hoyle & Vogeley 2002) CELL Void Finder (Patiri et al. 2005) HB Void Finder (Patiri et al. 2005) Void Finding Process

14. Primary Results Mean Distance

15. Primary Results Redshift accuracy: ΔZ=0.01 Z=0.1 :Δd ≈ 40 Mpc Z=2.5 :Δd ≈ 11 Mpc

16. Open Problems Making algorithms to find voids in a narrow samples. Analysis of voids in high-redshift Universe. Time evolution of voids. …

17. References: 1. 1. عنبرانی، امیر؛ پایان نامه کارشناسی ارشد؛ دانشگاه فردوسی مشهد؛ 1385 2. 2. Cosmological evolution survey (COSMOS): http://cosmos.astro.caltech.edu/index.html 3. 3. Courteau S., Van den Bergh S.; Thr Astronomical Journal, 118:337-345, 1999 4. 4. El-Ad H., Piran T.; Voids in the large-scale structure; The astrophysical journal; 491:421-435, 1997 5. 5. Erdogdu P. et al.; Mon. Not. Roy. Astron. Soc.; 368:1515-1526; 2006 6. 6. Johnson D. R. H., Soderblom D.; The Astronomical Journal; 93: 864-867; 1987 7. 7. Peebles P.J.E; Principles of Physical Cosmology; Princeton University Press; 1993 8. 8. Weygaret & Kampen; Voids in gravitational instability scenarios; Mon. Not. Roy. Astron. Soc. 263: 481-526; 1993

18. Thanks for Your Attention