PROTO-GROUPS AT 1.8 \textless z \textless 3 IN THE zCOSMOS-DEEP SAMPLE
C. Diener
,
S. J. Lilly
(1)
,
C. Knobel
(2)
,
G. Zamorani
(3)
,
G. Lemson
,
P. Kampczyk
(2)
,
N. Scoville
(4)
,
C. M. Carollo
(5)
,
T. Contini
(6)
,
J. -P. Kneib
(7)
,
O. Le Fevre
(8)
,
V. Mainieri
(9)
,
A. Renzini
(10)
,
M. Scodeggio
(11)
,
S. Bardelli
(12)
,
M. Bolzonella
(3)
,
A. Bongiorno
(13)
,
K. Caputi
(2)
,
O. Cucciati
(14)
,
S. de La Torre
(8)
,
L. De Ravel
,
P. Franzetti
(2)
,
B. Garilli
(2)
,
A. Iovino
(2)
,
K. Kovac
(2)
,
F. Lamareille
(15)
,
J. -F. Le Borgne
,
V. Le Brun
(8)
,
C. Maier
(16)
,
M. Mignoli
(3)
,
R. Pelló
(15)
,
Y. Peng
(17)
,
E. Perez Montero
(6)
,
V. Presotto
(18, 19)
,
J. Silverman
(2)
,
M. Tanaka
,
L. Tasca
(8)
,
L. Tresse
(8)
,
D. Vergani
(20)
,
E. Zucca
(21)
,
R. Bordoloi
,
A. Cappi
(22)
,
Alessandro Cimatti
(20)
,
G. Coppa
(2)
,
A. M. Koekemoer
(23)
,
C. Lopez-Sanjuan
(8)
,
H. J. Mccracken
(24)
,
M. Moresco
,
P. Nair
(12)
,
L. Pozzetti
(3)
,
N. Welikala
(8)
1
ETH Zürich -
Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich]
2 AUTRES
3 IASF-Bo - Istituto di Astrofisica Spaziale e Fisica cosmica - Bologna
4 CALTECH - California Institute of Technology
5 University of Chicago
6 LATT - Laboratoire Astrophysique de Toulouse-Tarbes
7 EPFL - Ecole Polytechnique Fédérale de Lausanne
8 LAM - Laboratoire d'Astrophysique de Marseille
9 ESO - European Southern Observatory
10 OAPD - INAF - Osservatorio Astronomico di Padova
11 INAF- Milano
12 OABO - INAF - Osservatorio Astronomico di Bologna
13 GATECH - College of Computing
14 Dipartimento di Fisica
15 IRAP - Institut de recherche en astrophysique et planétologie
16 LLB - UMR 12 - Laboratoire Léon Brillouin
17 HNU - Hunan Normal University
18 Università degli studi di Trieste = University of Trieste
19 OAT - INAF - Osservatorio Astronomico di Trieste
20 OAA - INAF - Osservatorio Astrofisico di Arcetri
21 OAB - INAF - Osservatorio Astronomico di Brera
22 LAGRANGE - Joseph Louis LAGRANGE
23 STSci - Space Telescope Science Institute
24 IAP - Institut d'Astrophysique de Paris
2 AUTRES
3 IASF-Bo - Istituto di Astrofisica Spaziale e Fisica cosmica - Bologna
4 CALTECH - California Institute of Technology
5 University of Chicago
6 LATT - Laboratoire Astrophysique de Toulouse-Tarbes
7 EPFL - Ecole Polytechnique Fédérale de Lausanne
8 LAM - Laboratoire d'Astrophysique de Marseille
9 ESO - European Southern Observatory
10 OAPD - INAF - Osservatorio Astronomico di Padova
11 INAF- Milano
12 OABO - INAF - Osservatorio Astronomico di Bologna
13 GATECH - College of Computing
14 Dipartimento di Fisica
15 IRAP - Institut de recherche en astrophysique et planétologie
16 LLB - UMR 12 - Laboratoire Léon Brillouin
17 HNU - Hunan Normal University
18 Università degli studi di Trieste = University of Trieste
19 OAT - INAF - Osservatorio Astronomico di Trieste
20 OAA - INAF - Osservatorio Astrofisico di Arcetri
21 OAB - INAF - Osservatorio Astronomico di Brera
22 LAGRANGE - Joseph Louis LAGRANGE
23 STSci - Space Telescope Science Institute
24 IAP - Institut d'Astrophysique de Paris
C. Diener
- Fonction : Auteur
G. Zamorani
- Fonction : Auteur
- PersonId : 755662
- ORCID : 0000-0002-2318-301X
- IdRef : 190956429
G. Lemson
- Fonction : Auteur
T. Contini
- Fonction : Auteur
- PersonId : 178293
- IdHAL : thierry-contini
- ORCID : 0000-0003-0275-938X
- IdRef : 112340571
O. Le Fevre
- Fonction : Auteur
- PersonId : 17465
- IdHAL : olivier-le-fevre
- ORCID : 0000-0001-5891-2596
- IdRef : 070374678
S. Bardelli
- Fonction : Auteur
- PersonId : 755650
- ORCID : 0000-0002-8900-0298
L. De Ravel
- Fonction : Auteur
J. -F. Le Borgne
- Fonction : Auteur
M. Tanaka
- Fonction : Auteur
L. Tresse
- Fonction : Auteur
- PersonId : 743336
- IdHAL : laurence-tresse
- ORCID : 0000-0001-8776-0958
- IdRef : 088004031
E. Zucca
- Fonction : Auteur
- PersonId : 755651
- ORCID : 0000-0002-5845-8132
R. Bordoloi
- Fonction : Auteur
M. Moresco
- Fonction : Auteur
- PersonId : 761800
- ORCID : 0000-0002-7616-7136
Résumé
We identify 42 “candidate groups” lying between 1.8\textlessz\textless3.0 from a sample of 3502 galaxies with spectroscopic redshifts in the zCOSMOS-deep redshift survey within this same redshift interval. These systems contain three to five spectroscopic galaxies that lie within 500 kpc in projected distance (in physical space) and within 700 km s(-1) in velocity. Based on extensive analysis of mock catalogs that have been generated from the Millennium simulation, we examine the likely nature of these systems at the time of observation, and what they will evolve into down to the present epoch. Although few of the “member” galaxies are likely to reside in the same halo at the epoch we observe them, 50% of the systems will have, by the present epoch, all of the member galaxies in the same halo, and almost all (93%) will have at least some of the potential members in the same halo. Most of the candidate groups can therefore be described as “proto-groups.” A crude estimate of the overdensities of these structures is also consistent with the idea that these systems are being seen as they assemble. We also examine present-day halos and ask whether their progenitors would have been seen among our candidate groups. For present-day halos between 10(14) and 10(15) M(circle dot)h(-1), 35% should have appeared among our candidate groups, and this would have risen to 70% if our survey had been fully sampled, so we can conclude that our sample can be taken as representative of a large fraction of such systems. There is a clear excess of massive galaxies above 10(10)M(circle dot) around the locations of the candidate groups in a large independent COSMOS photo-z sample, but we see no evidence in this latter data for any color differentiation with respect to the field. This is, however, consistent with the idea that such differentiation arises in satellite galaxies, as indicated at z \textless1, if the candidate groups are indeed only starting to be assembled.