2007A&A...461..823V


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.14CEST01:00:57

2007A&A...461..823V - Astronomy and Astrophysics, volume 461, 823-845 (2007/1-3)

Protoclusters associated with z > 2 radio galaxies. I. Characteristics of high redshift protoclusters.

VENEMANS B.P., ROETTGERING H.J.A., MILEY G.K., VAN BREUGEL W.J.M., DE BREUCK C., KURK J.D., PENTERICCI L., STANFORD S.A., OVERZIER R.A., CROFT S. and FORD H.

Abstract (from CDS):

We present the results of a large program conducted with the Very Large Telescope and augmented by observations with the Keck telescope to search for forming clusters of galaxies near powerful radio galaxies at 2.0<z<5.2. Besides MRC 1138-262 at z=2.16, the radio galaxy observed in our pilot program, we obtained narrow- and broad-band images of eight radio galaxies and their surroundings. The imaging was used to select candidate Lyα emitting galaxies in ∼3x3Mpc2 areas near the radio galaxies. A total of 300 candidate emitters were found with a rest-frame Lyα equivalent width of EW0>15Å and significance Σ=EW0/ΔEW0>3. Follow-up spectroscopy was performed on 152 candidates in seven of the radio galaxy fields. Of these, 139 were confirmed to be Lyα emitters, four were low redshift interlopers and nine were non-detections. With the adopted criteria the success rate is 139/152=91%. In addition, 14 objects with EW0<15 and/or Σ<3 were confirmed to be Lyα emitters. Combined with the 15 Lyα emitters near MRC 1138-262, we have determined Lyα redshifts for 168 objects near eight radio galaxies. At least six of our eight fields are overdense in Lyα emitters by a factor 3-5 as compared to the field density of Lyα emitters at similar redshifts, although the statistics in our highest redshift field (z=5.2) are poor. Also, the emitters show significant clustering in velocity space. In the overdense fields, the width of the velocity distributions of the emitters is a factor 2-5 smaller than the width of the narrow-band filters. Taken together, we conclude that we have discovered six forming clusters of galaxies (protoclusters). We estimate that roughly 75% of powerful (L2.7GHz>1033erg/s/Hz/sr) high redshift radio galaxies reside in a protocluster. The protoclusters have sizes of at least 1.75Mpc, which is consistent with the structure sizes found by other groups. By using the volume occupied by the overdensities and assuming a bias parameter of b=3-6, we estimate that the protoclusters have masses in the range 2-9x1014M. These protoclusters are likely to be progenitors of present-day (massive) clusters of galaxies. For the first time, we have been able to estimate the velocity dispersion of cluster progenitors from z∼5 to ∼2. The velocity dispersion of the emitters increases with cosmic time, in agreement with the dark matter velocity dispersion in numerical simulations of forming massive clusters.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: clusters: general - cosmology: observations - cosmology: early Universe - cosmology: large scale structure of Universe

VizieR on-line data: <Available at CDS (J/A+A/461/823): table1.dat tablea1.dat tablea2.dat tablea3.dat tablea4.dat tablea5.dat>

Nomenclature: NAME MRC 0052-241 Protocluster N=1. Tables A1-A3: [VRM2007] HHMM.LAENN N=3+37+28. Tables A4-A5: [VRM2007] JHHMM.LAENN N=11+37.

Status at CDS : All or part of tables of objects could be ingested in SIMBAD with priority 2.

Simbad objects: 25

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Number of rows : 25

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 CD-34 239 PM* 00 41 30.4742099792 -33 37 32.032402561 13.138 11.969 10.525 9.619 8.741 K9V 101 0
2 PMN J0054-2351 rG 00 54 29.80 -23 51 32.0           ~ 23 1
3 NAME MRC 0052-241 Protocluster ClG 00 54 29.80 -23 51 32.0           ~ 3 0
4 CD-28 595 PM* 01 54 50.2704861570 -27 28 35.740415025   12.06 11.51     ~ 123 0
5 NAME MRC 0316-257 Protocluster ClG 03 18 12.00 -25 35 09.0           ~ 7 0
6 NVSS J031812-253509 rG 03 18 12.00 -25 35 09.0   23.6 23.8     ~ 73 2
7 LP 995-86 PM* 03 48 22.6125635562 -39 08 37.013516494   13.61 13.15     F 92 0
8 [DVR2000] TN J0924-2201 rG 09 24 19.94 -22 01 42.2       25.850   ~ 79 0
9 PMN J0945-2429 rG 09 45 32.7 -24 28 49           ~ 91 1
10 NAME MRC 0943-242 Protocluster ClG 09 45 32.8 -24 28 49           ~ 5 0
11 GD 108 HS* 10 00 47.2462037648 -07 33 30.777365253 12.406 13.349 13.563 13.662 13.781 sdB 132 1
12 NAME Spiderweb Galaxy AGN 11 40 48.3 -26 29 09     22.00     ~ 255 1
13 NAME MRC 1138-262 Protocluster ClG 11 40 48.4 -26 29 11           ~ 25 0
14 BD+18 2647 HS* 12 41 51.7901702595 +17 31 19.750592670 10.261 11.70 11.63 11.969 12.159 sdOpec 166 1
15 ClG J1252-2927 ClG 12 52 54.4 -29 27 17           ~ 151 0
16 NAME Subaru Deep Field NGP reg 13 24 21.3 +27 29 23           ~ 309 1
17 NAME TN 1338 Protocluster C?G 13 38 26.05 -19 42 30.5           ~ 7 0
18 [DBC2004] M03 rG 13 38 26.05 -19 42 30.5       22.4   ~ 91 0
19 LP 916-15 PM* 15 38 59.6477173130 -28 35 36.970418054   12.19 11.62     A 107 0
20 PKS J1605-1734 rG 16 05 02.2 -17 34 16           ~ 24 1
21 CD-38 10980 WD* 16 23 33.8384178546 -39 13 46.160032569 9.916 10.885 11.029 10.936 10.841 DA2 446 0
22 TXS 2006-308 QSO 20 09 47.9 -30 40 04           ~ 17 1
23 CD-30 17706 WD* 20 10 56.8485174654 -30 13 06.629141494 11.654 12.286 12.242 12.311 12.381 DA3.1 226 0
24 PMN J2051-2702 rG 20 51 03.6 -27 03 03           ~ 33 1
25 Feige 110 HS* 23 19 58.3995050606 -05 09 56.170282845 10.360 11.45 11.50 11.970 12.145 sdO8VIIIHe5 575 1

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2021.04.14-01:00:57

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