HAL : hal-00391679, version 1

arXiv : 0903.3411

Code Bibliographique ADS : 2009ApJ...697.1842K

DOI : 10.1088/0004-637X/697/2/1842

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The Astrophysical Journal 697 (2009) 1842-1860

An Optical Group Catalog to z = 1 from the zCOSMOS 10 k Sample

C. Knobel, S. J. Lilly, A. Iovino, C. Porciani, K. Kovač, O. Cucciati, A. Finoguenov, M. G. Kitzbichler, C. M. Carollo, T. Contini 1, J.-P. Kneib 2, O. Lefèvre 2, V. Mainieri, A. Renzini, M. Scodeggio, G. Zamorani, S. Bardelli, M. Bolzonella 3, A. Bongiorno 3, K. Caputi, G. Coppa, S. de la Torre 2, L. de Ravel, P. Franzetti, B. Garilli, P. Kampczyk, F. Lamareille 1, 4, J.-F. Leborgne 1, V. Lebrun 2, C. Maier, M. Mignoli, R. Pello 1, Y. Peng, E. Perez Montero 1, E. Ricciardelli, J. D. Silverman, M. Tanaka, L. Tasca 2, L. Tresse 2, D. Vergani 5, 6, 7, E. Zucca, U. Abbas, D. Bottini, A. Cappi, P. Cassata, A. Cimatti, M. Fumana, L. Guzzo, A. M. Koekemoer, A. Leauthaud 1, D. Maccagni, C. Marinoni 8, H. J. McCracken 9, P. Memeo, B. Meneux, P. Oesch, L. Pozzetti, R. Scaramella

(06/2009)

We present a galaxy group catalog spanning the redshift range 0.1 lsim z lsim 1 in the ~ 1.7 deg2 COSMOS field, based on the first ~10,000 zCOSMOS spectra. The performance of both the Friends-of-Friends (FOF) and Voronoi-Delaunay method (VDM) approaches to group identification has been extensively explored and compared using realistic mock catalogs. We find that the performance improves substantially if groups are found by progressively optimizing the group-finding parameters for successively smaller groups, and that the highest fidelity catalog, in terms of completeness and purity, is obtained by combining the independently created FOF and VDM catalogs. The final completeness and purity of this catalog, both in terms of the groups and of individual members, compares favorably with recent results in the literature. The current group catalog contains 102 groups with N >= 5 spectroscopically confirmed members, with a further ~700 groups with 2 <= N <= 4. Most of the groups can be assigned a velocity dispersion and a dark-matter mass derived from the mock catalogs, with quantifiable uncertainties. The fraction of zCOSMOS galaxies in groups is about 25% at low redshift and decreases toward ~15% at z ~ 0.8. The zCOSMOS group catalog is broadly consistent with that expected from the semianalytic evolution model underlying the mock catalogs. Not least, we show that the number density of groups with a given intrinsic richness increases from redshift z ~ 0.8 to the present, consistent with the hierarchical growth of structure. European Southern Observatory (ESO), Large Program 175.A-0839.

1 :	Laboratoire Astrophysique de Toulouse-Tarbes (LATT)
	CNRS : UMR5572 – INSU – Observatoire Midi-Pyrénées – Université Paul Sabatier [UPS] - Toulouse III
2 :	Laboratoire d'Astrophysique de Marseille (LAM)
	CNRS : UMR6110 – INSU – Université de Provence - Aix-Marseille I
3 :	INAF- Osservatorio Astronomico di Bologna (INAF)
	INAF
4 :	Istituto Nazionale di Astrofisico -Osservatorio Astronomico di Bologna (INAF)
	INAF
5 :	Autres
	AUTRE
6 :	INAF- Milano
	INAF
7 :	INAF, Osservatorio Astrofisico di Arcetri, Largo
	Osservatorio Astrofisico di ArcetI
8 :	Centre de Physique Théorique (CPT)
	CNRS : FR2291 – Université de Provence - Aix-Marseille I – Université de la Méditerranée - Aix-Marseille II – Université Sud Toulon Var
9 :	Institut d'Astrophysique de Paris (IAP)
	CNRS : UMR7095 – INSU – Université Pierre et Marie Curie [UPMC] - Paris VI

Domaine

:

Planète et Univers/Astrophysique/Astrophysique galactique

Mots Clés : catalogs – galaxies: clusters: general – galaxies: high-redshift – methods: data analysis

hal-00391679, version 1

http://hal.archives-ouvertes.fr/hal-00391679

oai:hal.archives-ouvertes.fr:hal-00391679

Contributeur : Dominique Lullier <>

Soumis le : Jeudi 4 Juin 2009, 14:36:16

Dernière modification le : Jeudi 4 Juin 2009, 14:36:16