THE DENSITY FIELD OF THE 10k zCOSMOS GALAXIES

Journal Article · Fri Jan 01 04:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/708/1/505· OSTI ID:21392454

Kovac, K; Lilly, S J; Porciani, C; Oesch, P; Knobel, C; Peng, Y; Carollo, C M; Caputi, K; Silverman, J D ^[1]; Cucciati, O; Iovino, A ^[2]; Zamorani, G; Bolzonella, M; Pozzetti, L; Vergani, D ^[3]; Finoguenov, A ^[4]; Tasca, L A. M. ^[5]; Scodeggio, M ^[6]; Scoville, N Z; Capak, P ^[7]

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1. Institute of Astronomy, ETH Zuerich, CH-8093, Zuerich (Switzerland)
2. INAF Osservatorio Astronomico di Brera, Milan (Italy)
3. INAF Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127, Bologna (Italy)
4. Max-Planck-Institut fuer extraterrestrische Physik, D-84571 Garching (Germany)
5. Laboratoire d'Astrophysique de Marseille, Marseille (France)
6. INAF-IASF Milano, Milan (Italy)
7. California Institute of Technology, MS 105-24, Pasadena, CA 91125 (United States)

We use the current sample of approx10,000 zCOSMOS spectra of sources selected with I{sub AB} < 22.5 to define the density field out to z approx 1, with much greater resolution in the radial dimension than has been possible with either photometric redshifts or weak lensing. We present the new algorithm that we have developed (ZADE) to incorporate objects not yet observed spectroscopically by modifying their photometric redshift probability distributions using the spectroscopic redshifts of nearby galaxies. We present a number of tests on mock catalogs used to justify this approach. The ZADE algorithm allows us to probe a broader range of galaxy environments and reduce the Poisson noise in the density field. The reconstructed overdensity field of the 10k zCOSMOS galaxies consists of cluster-like patterns surrounded by void-like regions, extending up to z approx 1. Some of these structures are very large, spanning the approx50 h {sup -1} Mpc transverse direction of the COSMOS field and extending up to DELTAz approx 0.05 in redshift. We present the three-dimensional overdensity maps and compare the reconstructed overdensity field to the independently identified virialized groups of galaxies and clusters detected in the visible and in X-rays. The distribution of the overdense structures is in general well traced by these virialized structures. A comparison of the large-scale structures in the zCOSMOS data and in the mock catalogs reveals an excellent agreement between the fractions of the volume enclosed in structures of all sizes above a given overdensity between the data and the mocks in 0.2 < z < 1, although in the data these overdense regions are in generally larger contiguous structures.

• OSTI ID: 21392454
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 708; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALGORITHMS
GALAXIES
MATHEMATICAL LOGIC
RED SHIFT
THREE-DIMENSIONAL CALCULATIONS
UNIVERSE